JPH0965648A - Power source controller and load test method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source controller which can easily change the output voltage of a power source circuit without attaching/detaching the component of the power source circuit. SOLUTION: A power source controller 21a detects the output voltage Vo of a power source circuit as a control voltage ERR by means of output voltage detecting means R1 and R2. In addition, the controller 21a selects either an internal reference voltage Vref supplied from a built-in reference voltage source 66 or an external reference voltage Vref applied to the controller 21a from the outside by means of a switch 22. In addition, the controller compares the selected reference voltage with the control voltage ERR and outputs a control signal which controls the output voltage Vo of the power source circuit to a fixed value based on the results of the comparison.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for adjusting an output voltage of a power supply circuit to a voltage according to a reference voltage. Further, the present invention relates to a load test method for testing the operation of a load connected to a power supply circuit using a power supply control device.

[0002]

2. Description of the Related Art Generally, a power supply circuit which is incorporated in an electronic device such as a notebook computer and supplies an operating voltage to each section (hereinafter referred to as "load") of the electronic device controls the output voltage to be constant. The control unit (power supply control device) is provided.

For example, DC-DC which is one of power supply circuits
The converter is generally constructed as shown in FIG. This DC-DC converter includes a transistor T
r1, choke coil L1, flywheel diode D2, diode D1, smoothing capacitor C1, resistor R
1, a resistor R2 and a controller 60a.

An input voltage Vi is applied to the input terminal of the transistor Tr1. The control end of the transistor Tr1 is connected to the output terminal of the control unit 60a, and is turned on / off by the control unit 60a. The output end of the transistor Tr1 is connected to one end of the choke coil L1.

A flywheel diode D2 is provided between one end of the choke coil L1 and the ground. The anode of the diode D1 is connected to the other end of the choke coil L1. On the other hand, the cathode of the diode D1 is connected to the output end of the DC-DC converter.

A smoothing capacitor C1 is provided between the cathode of the diode D1 and the ground. Further, a series circuit of a resistor R1 and a resistor R2 is provided between the output end of the DC-DC converter and the ground. This series circuit is a detection circuit for the output voltage Vo.

The control unit 60a has an input terminal for the input voltage Vi of the DC-DC converter in addition to the above-mentioned output terminal. As a result, the input voltage Vi is applied as an operating voltage to the controller 60a. In addition, the control unit 60a
Is an input terminal for inputting an ON / OFF signal, which is a control command for the output voltage Vo, from the outside (hereinafter, “terminal SC”).
Say. )have. Further, the control unit 60a has an input terminal for the output voltage Vo (hereinafter referred to as "terminal FB").
have. This terminal FB has resistors R1 and R
It is connected to the contact point with 2. Thereby, the control unit 60
The detected value of the output voltage Vo appearing across the resistor R2 is input to a as the control voltage ERR.

The operation of such a DC-DC converter is roughly as follows. That is, the transistor T
When r1 is turned on, electric power is stored in the choke coil L1. When the transistor Tr1 is turned off, the flywheel diode D2 releases the electric power stored in the choke coil L1. And DC-
The output voltage Vo having a predetermined value is transformed and output to the output terminal of the DC converter. The resistors R1 and R2 detect the output voltage Vo as needed, and input the detected voltage to the control unit 60a as the control voltage ERR. The controller 60a controls ON / OFF of the transistor Tr1 based on the control voltage ERR in order to keep the output voltage Vo constant at a predetermined value.

Therefore, the control unit 60a is constructed as shown in FIG. The control unit 60a uses a single L
It is composed of SI (Large Scale Integration circuit) and has a built-in reference voltage source 66, an error amplifier (error amplifier) 61, and a PWM (Pulse-Width Modulation) comparator 6.
2, power source 63, triangular wave oscillator 64 and drive circuit 65
It has.

The power supply 63 is connected to the input terminal of the input voltage Vi and the terminal SC, and forms the operating power of each part of the control unit 60a from the input voltage Vi. Further, the power source 63 supplies operating power to each unit of the control unit 60a when the ON / OFF signal input from the outside is “ON”. The control voltage ERR is input to the error amplifier 61 from its negative-phase input terminal, and the reference voltage e1 is input from the positive-phase input terminal. Then, the error amplifier 61
However, the difference between the control voltage ERR and the reference voltage e1 is detected and amplified, and the result is output.

The output terminal of the error amplifier 61 is connected to the positive phase input terminal of the PWM comparator 62. On the other hand, PWM
A triangular wave oscillator 64 is connected to the negative phase input terminal of the comparator 62. Here, the triangular wave oscillator 64 generates a conversion triangular wave signal for converting a voltage into a pulse width at a constant frequency. Then, the PWM comparator 62
When the differential amplification result of the error amplifier 61 is input as an output signal from the positive phase input terminal and the triangular wave signal is input from the negative phase input terminal, the PWM of the pulse width and the pulse interval corresponding to the difference is input. Generate a signal.

One end of the drive circuit 65 is connected to the PWM comparator 62, and the other end is connected to the control terminal connected to the control end of the transistor Tr1. As a result, the drive circuit 65 turns on / off the transistor Tr1 based on the PWM signal input from the PWM comparator 62.
Control OFF.

The control unit 60a having such a configuration controls the input voltage Vi.
Is applied as the operating voltage and the "ON" signal which is a control command of the output voltage Vo is input to the terminal SC, the following operation is performed.

That is, when the control voltage ERR is input from the terminal FB into the control unit 60a, this control voltage ERR is input.
Is input to the error amplifier 61. On the other hand, the reference voltage e1 is input to the error amplifier 61 from the built-in reference voltage source 66. Then, the error amplifier 61 causes the control voltage ER
The error between R and the reference voltage e1 is detected and amplified, and the result is input to the PWM comparator 62 as an output signal. On the other hand, the triangular wave oscillator 64 inputs the triangular wave signal to the PWM comparator 62.

The PWM comparator 62 compares the output signal of the error amplifier 61 with the triangular wave signal. At this time, when the output signal of the error amplifier 61 is larger than the output signal of the triangular wave oscillator 64, the PWM comparator 62 generates a PWM signal for turning on the transistor Tr1 and drives the PWM signal. Input to the circuit 65. Then, the drive circuit 65 gives the PWM signal input from the PWM comparator 62 to the transistor Tr1.

As a result, the transistor Tr1 is turned on, and the output voltage Vo is applied to the output end side of the transistor Tr1.
Is applied at a predetermined value to keep it constant. By repeating such operations, the output voltage Vo having a predetermined value is constantly output to the output terminal of the DC-DC converter.

By the way, when the power supply circuit such as the DC-DC converter described above is actually mounted and used in an electronic device, the characteristics of the constituent elements of the power supply circuit change due to temperature changes around the electronic device. However, this may change the output voltage of the power supply circuit. Therefore, when manufacturing an electronic device, a voltage range (hereinafter referred to as "margin") is ensured in which the load can normally operate even when the output voltage of the power supply circuit changes from a predetermined value. Is generally manufactured. Then, before shipping the electronic device to the market, if the output voltage of the power supply circuit incorporated in the electronic device changes, a load test to confirm whether the load operates normally within the margin ( , "Margin test").

When this margin test is performed on an electronic device incorporating the DC-DC converter shown in FIGS. 12 and 13, the configuration of the DC-DC converter shown in FIG. 12 is shown in FIG. Will be changed to That is, the resistor R2 shown in FIG.
As shown in FIG. 5, the output voltage Vo, which is replaced by the variable resistor R3 and detected by the resistors R1 and R3, that is, the control voltage ERR is made variable. And
The operating state of the load is tested by changing the value of the control voltage ERR accordingly. The electronic device that has passed this margin test is shipped to the market after the variable resistor R3 of the DC-DC converter is replaced with the resistor R2 again.

[0019]

However, since this margin test is performed for each electronic device, the DC-D of the electronic device is not tested.
The replacement work of the resistors R2 and R3 in the C converter had to be performed for each electronic device. This has a problem that a huge man-hour is required in combination with the adjustment work of the variable resistor R3.

In recent years, the load of electronic equipment has become IC.
(Integrated Circuit) or LSI (for example, CPU (Cen
In many cases, the operating voltage of the load is becoming lower. Therefore, the load margin is reduced and the load yield is deteriorated.

On the other hand, the power supply circuit of electronic equipment is required to supply a highly accurate output voltage to the load as the load margin decreases. In order to meet this demand, the accuracy of output and the reliability of the power supply circuit are improved by incorporating the constituent elements of the power supply circuit into the power supply control device as much as possible. For example, referring to FIG. 12 and FIG.
The resistor R1 and the resistor R2 of the DC-DC converter shown in FIG. 7 are becoming built in the control unit 60b as shown in FIGS.

However, in the DC-DC converter in which the resistor R1 and the resistor R2 are built in the control unit 60b, it becomes impossible to attach and detach the resistor R2. Therefore, in order to make the control voltage ERR variable for the margin test, for example, the transistor Tr1 shown in FIG. 15 is removed, and a variable voltage source is newly connected to one end of the choke coil L1 or the choke coil L1 is connected. I had to remove and attach a variable voltage source. Therefore, there is a problem that the margin test is very troublesome.

Therefore, the margin test actually performed is
It is performed for some electronic devices selected from a large number of electronic devices planned to be manufactured at one time. If all of the selected electronic devices pass the margin test, it is considered that all of the large number of electronic devices scheduled to be shipped have passed the margin test, and are shipped to the market.

As described above, since the margin test has not been performed on all the shipped electronic devices, among the electronic devices shipped without passing the margin test, the load does not operate normally within the margin. Could also exist. However, as described above, since the margin test is very troublesome, it is extremely difficult to perform the margin test on all the electronic devices.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply control device capable of easily varying the output voltage of a power supply circuit without attaching or detaching the constituent elements of the power supply circuit. . Also, using the power supply control device,
An object is to provide a load test method for testing the operation of a load connected to a power supply circuit.

[0026]

The power supply control device according to the present invention adopts the following constitution in order to solve the above-mentioned problems. That is, the power supply control device according to the present invention includes output voltage detection means for detecting the output voltage of the power supply circuit and a built-in reference voltage source for supplying a reference voltage, and the output voltage detected by the output voltage detection means and the built-in output voltage detection means. A power supply control device for comparing with a reference voltage supplied from a reference voltage source and outputting a control signal for controlling the output voltage of the power supply circuit to be constant based on the result of the comparison. A selector for selecting one of the reference voltage supplied from the built-in reference voltage source and an external reference voltage externally applied to the power supply control device as a voltage to be compared with the output voltage detected by the means. Characterize.

Here, the selection operation of the selector may be performed manually, for example, or may be performed automatically. The power supply control device according to the present invention further comprises an external input detection means for detecting the presence / absence of application of the external reference voltage, and the selector is configured to detect the reference voltage and the external reference voltage based on a detection result of the external input detection means. It is also possible to select one of the two.

The power supply control device according to the present invention includes an output voltage detection means for detecting the output voltage of the power supply circuit and a built-in reference voltage source for supplying the reference voltage, and the output voltage detected by the output voltage detection means. A power supply control device that compares a reference voltage supplied from a built-in reference voltage source and outputs a control signal that constantly controls the output voltage of the power supply circuit on the basis of the result of the comparison. A digital converter that converts the digital data of the external reference voltage input to the power supply control device to an analog external reference voltage.
Between the analog converter and the reference voltage supplied from the built-in reference voltage source as the voltage to be compared with the output voltage detected by the output voltage detecting means, and the external reference voltage converted by the digital-analog converter. And a selector for selecting one of them.

The power supply control device according to the present invention further comprises an external input detection means for detecting whether or not the external reference voltage is applied, and the selector is based on the detection result of the external input detection means. One of the external reference voltage and the external reference voltage may be selected.

The external input detection means detects the analog external reference voltage converted by the digital-analog converter, and the selector detects the reference voltage based on the detection result of the external input detection means. One of the external reference voltage may be selected.

The external input detecting means detects digital data of the external reference voltage input to the digital-analog converter, and the selector outputs the digital data based on the detection result of the external input detecting means. One of the reference voltage and the external reference voltage may be selected.

Here, the digital data detected by the external input means may be serial data or parallel data. Further, the digital data of the external reference voltage includes data for selecting operation of the selector, the selector detects data for selecting operation of the selector, and the built-in data is selected based on the data for selecting operation of the selector. One of the reference voltage from the reference voltage source and the external reference voltage converted by the digital-analog converter may be selected. The selector in this case has a function equivalent to that in the case where the external input detection means is built in.

In the power supply control device according to the present invention, the output voltage detection means for detecting the output voltage of the power supply circuit as a control voltage, the built-in reference voltage source for supplying the internal reference voltage, and the output voltage detection means for detecting the output voltage A selector for selecting one of the internal reference voltage supplied from the built-in reference voltage source and an external reference voltage source applied from the outside as a selection reference voltage to be compared with a control voltage, and the output voltage detection means Control signal generating means for generating a control signal for adjusting the output voltage of the power supply circuit to a voltage according to the selection reference voltage based on a comparison result of the control voltage and the selection reference voltage selected by the selector. And may be provided inside a single integrated circuit.

Further, the power supply control device of the present invention includes an output voltage detecting means for detecting the output voltage of the power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and an external reference voltage input from the outside. A digital-analog converter for converting the digital data of the above into an analog external reference voltage, and the internal reference supplied from the built-in reference voltage source as a selected reference voltage to be compared with the control voltage detected by the output voltage detection means. Voltage and the digital
A selector that selects one of the external reference voltage converted by the analog converter, based on a comparison result of the control voltage detected by the output voltage detection means and the selected reference voltage selected by the selector. A control signal generating unit that generates a control signal for adjusting the output voltage of the power supply circuit to a voltage according to the selection reference voltage may be provided inside a single integrated circuit.

Here, the integrated circuit may be an IC or an LSI as long as it is integrated into one chip. Further, the voltage corresponding to the selection reference voltage may be a voltage having the same value as the selection reference voltage or a voltage obtained by amplifying the selection reference voltage.

The load test method according to the present invention is configured as follows in order to solve the above-mentioned problems. That is, as an output voltage detection means for detecting the output voltage of the power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and a selection reference voltage to be compared with the control voltage detected by the output voltage detection means. A selector for selecting one of the internal reference voltage supplied from a built-in reference voltage source and an external reference voltage applied from the outside, the control voltage detected by the output voltage detection means, and the selector selected by the selector. A power supply control device comprising: a control signal generation unit that generates a control signal for adjusting an output voltage of the power supply circuit to a voltage according to the selection reference voltage based on a comparison result with a selection reference voltage. A load test method for testing the operation of a load connected to a circuit, comprising: It applies a et the external reference voltage,
The output voltage of the power supply circuit adjusted to a voltage according to the external reference voltage is supplied to the load by causing the selector to select the external reference voltage as the selection reference voltage.

The load test method according to the present invention comprises an output voltage detecting means for detecting the output voltage of the power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and a digital external reference voltage input from the outside. A digital-analog converter for converting data into an analog external reference voltage; and the internal reference voltage supplied from an internal reference voltage source as a selection reference voltage to be compared with the control voltage detected by the output voltage detecting means, and A selector that selects one of the external reference voltage converted by the digital-analog converter, a control voltage detected by the output voltage detection means, and a comparison result of the selected reference voltage selected by the selector. Based on the control signal for adjusting the output voltage of the power supply circuit to a voltage according to the selected reference voltage. A load test method for testing the operation of a load connected to the power supply circuit using a power supply control device including a control signal generating means for generating the power supply control device. An external output of the power supply circuit adjusted to a voltage according to the external reference voltage by externally inputting digital data of the external reference voltage to the selector and causing the selector to select the external reference voltage as the selection reference voltage. A voltage is supplied to the load.

In the load test of the present invention, the power supply control device is provided with an external input detecting means for detecting whether or not the external reference voltage is applied, and the selector determines the external reference based on the detection result of the external input detecting means. A voltage may be selected as the selection reference voltage.

The detection target of the external input detection means may be the external reference voltage converted by the digital-analog converter, or the external reference voltage input to the digital-analog converter. It may be digital data.

Further, the digital data of the external reference voltage includes data for selecting operation of the selector, the selector detects data for selecting operation of the selector, and based on the data for selecting operation of this selector. The external reference voltage converted by the digital / analog converter may be selected as the selection reference voltage.

According to the load test method of the present invention, the value of the output voltage of the power supply circuit supplied to the load is changed by changing the value of the external reference voltage input to the power supply control device or the digital data of the external reference voltage. May be changed.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION

<Outline of Embodiment> First, an outline of an embodiment of the power supply control device of the present invention will be described with reference to FIGS. 1 to 4. FIG.
The power supply control device 1a shown in (1) is composed of a single integrated circuit, and comprises an output voltage detection means 8, a built-in reference voltage source 2, a comparison and comparison means 3, a selector 4, and a control signal generation means 9.

The output voltage of the power supply circuit (not shown) is input to the output voltage detecting means 8. The output voltage detecting means 8 is
The output voltage input to itself is detected and input to the comparison means 3 as the control voltage b. One of the internal reference voltage a supplied from the built-in reference voltage source 2 and the external reference voltage d externally applied to the power supply control device 1a is used as a reference voltage (selection reference voltage) to be compared with the control voltage b. Is selected, and the selected reference voltage is input to the comparison means 3.

When the selector 4 selects the internal reference voltage a, the comparison means 3 determines the internal reference voltage a and the control voltage b.
And the result of the comparison is input to the control signal generation means 9. The control signal generation means 9 controls the output voltage of the power supply circuit to be constant based on the comparison result of the comparison means 3 (for adjusting the output voltage of the power supply circuit to a voltage according to the selected reference voltage). Control signal) is generated and output. With this control signal c, the output voltage of the power supply circuit is controlled to be constant with a voltage value that substantially matches the internal reference voltage a, for example.

On the other hand, when the selector 4 selects the external reference voltage d, the comparison means 3 compares the external reference voltage d with the control voltage b and inputs the comparison result to the control signal generation means 9. The control signal generation means 9 generates and outputs the control signal c for controlling the output voltage of the power supply circuit to be constant based on the comparison result of the comparison means 3. This control signal c
Thus, the output voltage of the power supply circuit is controlled to be constant with a voltage value that substantially matches the external reference voltage d, for example.

The power supply control device 1b shown in FIG.
The power supply control device 1a is provided with an external input detecting means 5 for detecting whether or not the external reference voltage d is applied. According to this power supply control device 1b, when the external reference voltage d is applied to the external input detection means 5, the external input detection means 5 inputs the switching signal f of the selector 4 to the selector 4. The selector 4 performs a selection operation and inputs the external reference voltage d to the comparison means 3.

The power supply control device 1c shown in FIG. 3 is premised on that the digital data e of the external reference voltage is input from the outside, and the power control device 1a of FIG. A digital / analog converter 6 for converting to an external reference voltage d;
The external input detecting means 5 for detecting the external reference voltage d converted by the analog converter 6 is added.

According to the power supply control device 1c, the selector 4 selects the reference voltage a of the built-in reference voltage source 2 when the external input detection means 5 does not detect an analog external reference voltage. On the other hand, when an analog external reference voltage d is output from the digital / analog converter 6, this external reference voltage d is applied to the external input detection means 5. As a result, the external input detection means 5 gives the selector 4 the switching signal f. Then, the selector 4 performs a selection operation to select the external reference voltage d, and this external reference voltage d is input to the comparison means 3.

The power supply control device 1d shown in FIG. 4 is premised on that the external reference voltage digital data e input to the power supply control device 1d includes the data for the selection operation of the selector 4. The selector 4 can be switched based on the digital data e.

According to the power supply control device 1d, when the digital data e of the external reference voltage source is input to the power supply control device 1d from the outside, the digital data e is input to the digital-analog converter 6 as well. , Is also given to the selector 4. Then, the selector 4 performs a selection operation to select the analog external reference voltage d converted by the digital-analog converter 6, and the external reference voltage d
Is input to the comparison means 3.

<First Embodiment> Next, the first embodiment of the present invention will be described.
An embodiment will be described. FIG. 5 shows the DC-DC converter 10 using the power supply control device according to the first embodiment as the control unit 21a. This DC-DC converter 10 corresponds to the power supply circuit of the present invention. This DC-DC converter 10 includes a transistor Tr1, a choke coil L1, a flywheel diode D2, and a diode D.
1, a capacitor C1 and a control unit 21a are provided.

The transistor Tr1 is a FET (Field Eff).
ect Transistor), and its input end is connected to the input end of the DC-DC converter 10. As a result, the input voltage Vi is applied to the input end of the transistor Tr1. The control end of the transistor Tr1 is connected to the output terminal of the control unit 21a. As a result, the transistor Tr1 is turned on / off by the operation of the control unit 21a. The output end of the transistor Tr1 is connected to one end of the choke coil L1.

The choke coil L1 stores electric power supplied when the transistor Tr1 is ON. A flywheel diode D2 is provided between one end of the choke coil L1 and the ground.
This flywheel diode D2 is a transistor T
The power stored in the choke coil L1 is released when r1 is OFF.

The anode of the diode D1 is connected to the other end of the choke coil L1. On the other hand, the cathode of the diode D1 is connected to the output end of the DC-DC converter 10. This diode D1 is DC-DC
The backflow current from a load (not shown) connected to the output terminal of the converter 10 is shielded.

A capacitor C1 is provided between the cathode of the diode D1 and the ground. Capacitor C
1 is to remove the pulsating component from the output voltage Vo. The smoothed voltage is D by this capacitor C1.
The output voltage Vo is output from the output terminal of the C-DC converter 10.

The control section 21a has an input terminal for the input voltage Vi of the DC-DC converter 10 in addition to the above-mentioned output terminal. As a result, the input voltage Vi is applied as an operating voltage to the control unit 21a. Control unit 2
1a is ON / O which is a control command for stabilizing the output voltage Vo.
Input terminal for inputting FF signal from outside (hereinafter,
It is called "terminal SC". )have. Control unit 2
1a is an input terminal of the output voltage Vo (hereinafter, "terminal FB")
Say. )have. The terminal FB is connected between the diode D1 and the output end of the DC-DC converter 10. As a result, the controller 21a has a DC-D
The output voltage Vo of the C converter 10 is input. Further, the control unit 21a has a terminal (hereinafter referred to as "terminal OSV") for inputting an external reference voltage Vref applied from an external reference voltage source (not shown).

Next, the internal structure of the controller 21a will be described with reference to FIG. The control unit 21a is composed of a single LSI, and has a built-in reference voltage source 66, an error amplifier (error amplifier) 61, a PWM comparator 62, a power supply 63, a triangular wave oscillator 64, a drive circuit 65, a resistor R1, and a resistor R2. , A resistor R4, a switch (selector) 22, a comparator 23 and a comparison voltage source 30. The power supply 63 has an input voltage V
It is connected to the input terminal of i and the terminal SC. The power supply 63 supplies the operating power of each part of the controller 21a to the input voltage Vi.
Formed from Further, the power supply 63 supplies operating power to each unit of the control unit 21a when the ON / OFF signal input from the outside is “ON”. On the other hand, the power source 63
Indicates that the ON / OFF signal input from the outside is "OFF"
If so, the supply of operating power is stopped. Therefore,
ON / OFF of the transistor Tr1 by the control unit 21a
For control, the ON / OFF signal input to the power supply 63 is “O”.
If it is N ″, it is performed.

The triangular wave oscillator 64 outputs a triangular wave signal for conversion for converting a voltage into a pulse width at a constant frequency. One end of the resistor R1 is connected to the terminal FB, and the other end of the resistor R1 is connected to one end of the resistor R2. The other end of the resistor R2 is grounded. As a result, the output voltage Vo is detected as the control voltage ERR at the contact point between the resistor R1 and the resistor R2. These resistors R1 and R2
Is the output voltage detecting means of the present invention.

The error amplifier 61 is composed of an operational amplifier. The negative phase input terminal of this error amplifier 61 is
It is connected to the contacts of the resistors R1 and R2. On the other hand, the positive phase input terminal of the error amplifier 61 is connected to the output terminal α of the switch 22. The switch 22 has a switching input terminal β and a switching input terminal γ in addition to the output terminal α described above. The switching input terminal β is connected to the built-in reference voltage source 66. On the other hand, the switching input terminal γ is connected to the terminal OSV via the signal line. As a result, the switch 22
Is an internal reference voltage e supplied from the internal reference voltage source 66.
One of 1 and an external reference voltage Vref supplied from an external reference voltage source (not shown) via a terminal OSV is selected as a selection reference voltage and is input to the error amplifier 61. Therefore, in the error amplifier 61,
The internal reference voltage e1 or the external reference voltage Vref is input from the negative phase input terminal, and the control voltage ERR is input from the positive phase input terminal. Then, the error amplifier 61 uses the internal reference voltage e1 or the external reference voltage Vref and the control voltage ER.
An error from R is detected and amplified. The error amplifier 61 corresponds to the comparison means.

The PWM comparator 62 has a positive-phase input terminal and a negative-phase input terminal, compares the signal input from the positive-phase input terminal with the signal input from the negative-phase input terminal, and compares them. It is a voltage pulse width converter that determines the ON time of an output pulse according to the difference between two input signals. That is, PW
The M comparator 62 is a signal (PW) having a pulse width and a pulse interval corresponding to the magnitude of the output signal of the error amplifier 61.
(M signal). This PWM comparator 62
Corresponds to the control signal generating means.

At the positive phase input terminal of the PWM comparator 62,
The output terminal of the error amplifier 61 is connected. On the other hand, P
A triangular wave oscillator 64 is connected to the negative phase input terminal of the WM comparator 62. Therefore, to the PWM comparator 62, the detection amplification result of the error amplifier 61 is input as an output signal from its positive phase input terminal, and the triangular wave signal is input from its negative phase input terminal. Here, the PWM comparator 62 outputs a HIGH-level PWM signal while the triangular wave signal input from the triangular wave oscillator 64 is higher than the output signal of the error amplifier 61. In contrast,
The PWM comparator 62 outputs a LOW-level PWM signal while the triangular wave signal input from the triangular wave oscillator 64 is lower than the output signal of the error amplifier 61.

One end of the drive circuit 65 is connected to the PWM comparator 62, and the other end is connected to the control terminal connected to the control end of the transistor Tr1. As a result, the drive circuit 65 turns on / off the transistor Tr1 based on the PWM signal input from the PWM comparator 62.
Control OFF. That is, the drive circuit 65
When the IGH-level PWM signal is input, the drive circuit 65 turns on the transistor Tr1. On the other hand, when the LOW-level PWM signal is input, the drive circuit 65 stops its operation.

The selection operation of the switch 22 is performed by receiving the output signal of the comparator 23. The positive phase input end of the comparator 23 is connected to the signal line connecting the switching input end γ and the terminal OSV. On the other hand, the negative phase input terminal of the comparator 23 is connected to the comparison voltage source 30.

The comparator 23 compares the external reference voltage Vref with the comparison voltage e2. When the external reference voltage Vref is larger than the comparison voltage e2, the HIGH signal is input to the switch 22 to output the external reference voltage Vref. Is smaller than the comparison voltage e2, the LOW signal is input to the switch 22.

The value of the comparison voltage e2 is set to a value smaller than the value of the external reference voltage Vref to be applied.
Therefore, the comparator 23 outputs a HIGH signal when the external reference voltage Vref is applied to the control section 21a. When the HIGH signal is given, the switch 22 selects the switching input terminal γ, and the LO
When the W signal is given, the switching input terminal β is selected. This comparator 23 corresponds to the external input detecting means of the present invention.

The signal line connecting the terminal OSV and the switching input terminal γ of the switch 22 is connected to one end of the resistor R4 and grounded at the other end. Accordingly, when the external reference voltage Vref is not supplied from the external reference voltage source (not shown), the terminal OSV and the switching input terminal γ of the switch 22 are
The potential of the signal line connecting to and becomes the ground potential.

The DC-DC converter 10 as described above is
It is mounted on an electronic device such as a notebook computer (not shown) and is used as a power supply circuit for a load (not shown) of the electronic device.
Hereinafter, the DC-DC converter 10 installed in the electronic device
An example of using the electronic device will be described for a case where the electronic device is normally used and a case where the above-described margin test (the load test method of the present invention) is performed. (1) When electronic device is normally used As a premise, the operator has the DC-DC shown in FIG.
The input voltage Vi is applied to the input terminal of the converter 10, and an ON signal is input to the control unit 21a from the terminal SC. In this case, the operator does not apply the external reference voltage Vref to the controller 21a.

Power is supplied to the power source 63 of the control section 21a, and an ON signal is input. The power source 63 is
Electric power is supplied to each unit of the control unit 21a according to the ON signal. Then, the triangular wave oscillator 64 outputs a triangular wave signal. Further, the comparison voltage source 30 outputs the comparison voltage e2 to the comparator 23.
To enter. On the other hand, as described above, the external reference voltage Vre
Since f is not applied, the ground voltage is input to the comparator 23. The comparator 23 compares the comparison voltage e2 with the ground voltage, and since the comparison voltage e2 is higher than the ground voltage, L
The OW signal is given to the switch 22.

Upon receiving the LOW signal from the comparator 23, the switch 22 selects the switching input terminal β. As a result, the internal reference voltage e1 is input from the built-in reference voltage source 66 to the error amplifier 61. On the other hand, the control voltage ERR detected by the resistors R1 and R2 is input to the error amplifier 61. However, at this time, the transistor Tr1 has never been turned on since the input voltage Vi was applied.
Since it is not N, the output voltage Vo is not output.
In this case, zero voltage is input to the error amplifier 61 as the control voltage ERR.

The error amplifier 61 compares the internal reference voltage e1 with the control voltage ERR, detects and amplifies these errors, and inputs the result to the PWM comparator 62 as an output signal. On the other hand, the PWM comparator 62 includes a triangular wave oscillator 64
A triangular wave signal is input from.

The PWM comparator 62 compares the output signal of the error amplifier 61 with the triangular wave signal. When the value of the control voltage ERR is zero, the triangular wave signal is transmitted to the error amplifier 61.
Since it is higher than the output signal of
The M signal is input to the drive circuit 65. The drive circuit 65 inputs the HIGH-level PWM signal to the control end of the transistor Tr1 shown in FIG. As a result, the transistor Tr1 is turned on.

Then, a voltage is applied to the output end of the transistor Tr1 and power is stored in the choke coil L1. When the transistor Tr1 is turned off, the flywheel diode D2 discharges the electric power stored in the choke coil L1. As a result, the output voltage Vo (voltage adjusted to correspond to the selected reference voltage) having a magnitude determined by the internal reference voltage e1 is output to the output terminal of the DC-DC converter 10.

This output voltage Vo is input to the control section 21a from the terminal FB at any time, and is detected as the control voltage ERR by the resistors R1 and R2 shown in FIG.
The control voltage ERR is input to the error amplifier 61 via the switch 22. Then, the error amplifier 61
The result of detecting and amplifying the error between the control voltage ERR and the internal reference voltage e1 is input to the PWM comparator 62.

The PWM comparator 62 compares the output signal of the error amplifier 61 with the triangular wave signal to generate a PWM signal of HIGH level or LOW level, and the drive circuit 6
Enter in 5. Then, the drive circuit 65 is HIGH
Each time a level PWM signal is input, the transistor Tr
Turn 1 on. Such an operation is repeated.

As described above, the controller 21a controls the output voltage V
o is monitored, and when the output voltage Vo decreases below a voltage value determined by the internal reference voltage e1, the transistor Tr
Turn 1 on. Thereby, the DC-DC converter 1
The output voltage Vo having a value determined by the internal reference voltage e1 is constantly output to the output terminal of 0. That is, the output voltage Vo adjusted to the voltage according to the internal reference voltage e1 is
It is supplied as an operating voltage to the load, and the load operates normally. (2) When performing a margin test When performing a margin test, the operator presupposes that the operator applies the input voltage Vi to the input end of the DC-DC converter 10 shown in FIG. 5 and the terminal SC to the controller 21a. Input the ON signal from. Further, an external reference voltage Vref for margin test is applied from the terminal OSV.

Then, as described above, the power source 63 is turned on.
Electric power is supplied to each unit of the control unit 21a according to the signal, and the triangular wave oscillator 64 outputs the triangular wave signal to the PWM comparator 6
Enter 2 Further, the comparison voltage source 30 changes the comparison voltage e2
Is input to the comparator 23. On the other hand, the external reference voltage Vref input from the terminal OSV is input to the comparator 23. Then, the comparator 23 compares the comparison voltage e2 with the external reference voltage Vref, and the external reference voltage Vref is compared with the comparison voltage e2.
Since it is higher than the above, a HIGH signal is applied to the switch 22.

The switch 22 switches from the comparator 23 to HIGH.
When the signal is received, the switching input terminal γ is selected. As a result, the external reference voltage Vref is input to the error amplifier 61. Subsequent operations are the same as in the case of using the electronic device normally, and therefore the description thereof is omitted. Finally, the output voltage Vo adjusted to a value based on the external reference voltage Vref is constantly output to the output terminal of the DC-DC converter 10 and supplied to the load.

As a result, the operator can confirm whether or not the load normally operates at this output voltage Vo. Further, an operator operates an external reference voltage source (not shown) to appropriately change the value of the external reference voltage Vref for margin test and apply it to the control section 21a, thereby supplying the output voltage Vo having a plurality of values to the load. It becomes possible to do. Thereby, for example, by changing the operating voltage from the lower limit to the upper limit of the margin, it is possible to confirm whether or not the load normally operates within the margin.

The operator selects the external reference voltage Vref.
When the application of the voltage is stopped, the ground voltage is input to the comparator 23 instead of the external reference voltage Vref. As a result, the comparator 23 generates a LOW signal and supplies the LOW signal to the switch 22. Then, the switch 22 performs a selection operation and selects the switching input terminal β in place of the switching input terminal γ. As a result, the selected reference voltage becomes the external reference voltage V
The ref is switched to the internal reference voltage e1. That is, the electronic device is ready for shipment.

According to the power supply control device (control unit 21a) of the first embodiment, the switch 22 can select one of the internal reference voltage e1 and the external reference voltage Vref. Therefore, the value of the output voltage Vo supplied to the load can be changed by switching the switch 22. Therefore, the DC-DC converter 10
If the operating voltage is supplied to the load by
2 selects the internal reference voltage e1 supplied from the internal reference voltage source 66, the operating voltage V with high accuracy
o is supplied to the load.

On the other hand, when performing the margin test, if the external reference voltage Vref for the margin test is input to the control section 21a, the switch 22 selects the switching input terminal γ, and the output voltage Vo for the margin test is obtained. Is supplied to the load. Thereby, the margin test can be performed without exchanging the constituent elements of the DC-DC converter 10.

As a result, it is possible to reduce the labor of the margin test, improve the efficiency, and reduce the cost, and it is possible to perform the margin test on all the electronic devices in which the DC-DC converter 10 is mounted. Therefore, it can be confirmed that the loads of all the electronic devices shipped to the market operate normally within the margin. Therefore, it is possible to eliminate the failure of the electronic device caused by the load not operating normally within the margin.

Further, the selection operation of the switch 22 is performed by using the comparator 22 depending on whether or not the external reference voltage Vref is applied. Therefore, the selection operation of the switch 22 can be automatically performed, and the margin test can be performed more easily. Further, since the configuration for automating the selection operation of the switch 22 can be realized by a simple configuration such as the comparator 23, the control unit 21a does not become large and complicated.

From the control section 21a shown in FIG.
The comparator 23, the comparison voltage source 30, and the resistor R4 may be removed, and the selection operation of the switch 22 may be performed manually.

<Second Embodiment> Next, the second embodiment of the present invention will be described.
An embodiment will be described. FIG. 7 shows a DC-DC converter 10 that uses the power supply control device according to the second embodiment as the control unit 21b. This DC-DC converter 10 corresponds to the power supply circuit of the present invention. The DC-DC converter 10 has the same configuration as the DC-DC converter 10 according to the first embodiment except for the controller 21b. Therefore, the description of the common points is omitted, and the differences will be described.

In the control section 21b, instead of the terminal OSV described in the first embodiment, an input terminal for digital data of an external reference voltage value (hereinafter referred to as "terminal DI").
And a clock input terminal (hereinafter referred to as "terminal T").
Is provided. As shown in FIG. 8, a shift register 24 and a digital / analog converter (hereinafter referred to as “DAC”) 25 are provided inside the control unit 21b in addition to the configuration of the control unit 21a shown in FIG. ing.

The terminals DI and T are connected to the shift register 2
4 and is adapted to receive digital data and a clock. This shift register 24
Are connected to the DAC 25. As a result, the shift register 24 takes in the digital data of the external reference voltage value input in bit serial according to the clock input from the terminal T, converts the digital data into parallel data, and inputs the parallel data to the DAC 25. Has become.

Further, the shift register 24 is connected to a signal line connecting the terminal SC and the power source 63, so that an ON / OFF signal inputted from the terminal SC of the control section 21b is inputted. . As a result, the shift register 24 resets its own contents when the OFF signal is input.

The DAC 25 obtains an external reference voltage Vref (analog external reference voltage) by converting the parallel data of the external reference voltage value output from the shift register 24 into an analog signal and outputs the external reference voltage Vref. The DAC 25 can obtain a predetermined resolution such as 8 bits. The DAC 25 is connected to the switching input terminal γ of the switch 22 via a signal line.

On the other hand, the switching input terminal β of the switch 22 is connected to the built-in reference voltage source 66 as in the first embodiment. As a result, the switch 22 controls the reference voltage e1 from the internal reference voltage 66 and the external reference voltage Vre from the DAC 25.
One of f and f is selected and input to the error amplifier 61.

The switch 22 is the same as in the first embodiment.
The selection operation is performed by receiving the output signal from the comparator 23 (corresponding to the external input detecting means). Comparator 23
The positive-phase input end of is connected to the signal line that connects the DAC 25 and the switching input end γ of the switch 22. On the other hand, the negative phase input terminal of the comparator 23 is connected to the comparison voltage source 30. As a result, the comparator 23 receives the external reference voltage Vref.
And the comparison voltage e2 are input. And the comparator 23
Compares the magnitude relationship between the external reference voltage Vref and the comparison voltage e2, and outputs the result as a HIGH signal or a LOW signal.

Here, the comparator 23 determines that the external reference voltage Vre
When f is higher than the comparison voltage e2, the external reference voltage Vr
A HIGH signal is given to the switch 22 assuming that ef is applied. On the other hand, the external reference voltage Vref is equal to the comparison voltage e2.
LOW signal is provided to switch 22.

The value of the comparison voltage e2 is set to a value smaller than the external reference voltage Vref, and when the external reference voltage Vref is input to the comparator 23, the HIGH signal is given to the switch 22. It is like this. Then, the switch 22 selects the switching input end γ when it receives the HIGH signal, and selects the switching input end β when it receives the LOW signal.

DC-D provided with such a control section 21b
Similar to the first embodiment, the C converter 10 is mounted in an electronic device (not shown) and supplies an operating voltage to a load (not shown) of the electronic device. Below, DC installed in electronic equipment
-Examples of using the DC converter 10 will be described for a case where an electronic device is normally used and a case where a margin test is performed. (1) When electronic device is normally used As a premise, the operator operates the DC-DC converter 10
To the control unit 21b while applying the input voltage Vi to the
Input N signal. However, it is assumed that the operator does not input the digital data of the external reference voltage value and the clock.

Therefore, the external reference voltage Vref is not input to the comparator 23. Therefore, the comparator 23 is LOW.
The signal is applied to the switch 22. Then switch 22
Selects the switching input terminal β. As a result, the internal reference voltage e1 of the built-in reference voltage source 66 is input to the error amplifier 61. Further, the error amplifier 61 has a control voltage ERR.
Is entered. Since the operation thereafter is the same as the operation described in the first embodiment, the description is omitted. Finally, the output voltage Vo having a value corresponding to the internal reference voltage e1 is constantly output to the output terminal of the DC-DC converter 10, and the load operates normally. (2) When performing a margin test In this case, as a premise, the operator must set DC-DC
The input voltage Vi is applied to the converter 10, and the control unit 21b
An ON signal is input to the control unit 21b, and digital data and a clock having an external reference voltage value of a predetermined value are externally supplied.
To enter. At this time, the operator inputs digital data of the external reference voltage value for the margin test in bit serial.

This digital data is input to the shift register 24 of the control section 21b. Shift register 24
Converts the digital data into parallel data and inputs it to the DAC 25. The DAC 25 converts the parallel data into analog and generates the external reference voltage Vref.

The external reference voltage Vref is input to the comparator 23. On the other hand, the comparator 23 receives the comparison voltage e2 from the comparison voltage source 30. The comparator 23 compares the external reference voltage Vref with the comparison voltage e2 of the comparison voltage source 30. Since the external reference voltage Vref is higher than the comparison voltage e2, the comparator 23 gives a HIGH signal to the switch 22.

Then, the switch 22 selects the switching input terminal γ. As a result, the external reference voltage Vref is input to the error amplifier 61. Further, the control voltage ERR is input to the error amplifier 61. Since the operation thereafter is almost the same as the operation described in the first embodiment, the description thereof will be omitted. Then, the output voltage Vo having a value based on the external reference voltage Vref is constantly output to the output terminal of the DC-DC converter 10.

When the digital data input to the controller 21b is stopped, the comparator 23 receives the external reference voltage Vre.
f is not input. Therefore, the comparator 23 is
The W signal is applied to the switch 22. Then switch 22
Selects the switching input terminal β. That is, the switching input terminal γ
To the switching input terminal β is performed. Then, the reference voltage is changed from the external reference voltage Vref to the internal reference voltage e1, and the output voltage Vo based on the internal reference voltage e1 is output to the output terminal of the DC-DC converter 10. As a result, the electronic device is ready for shipment.

The effect of the power supply control device (control section 21b) according to the second embodiment is almost the same as the effect of the first embodiment, but the external reference voltage Vref can be generated by digital data. Therefore, the external reference voltage Vref can be set by software processing by the computer. Therefore, for example, if the start-up control of the control unit 21b is performed by the monitoring program that monitors the charge state and the discharge state of the battery power source, the battery can be automatically charged.

The control section 21b according to the second embodiment.
In order to reduce the number of input / output terminals as much as possible, digital data is input in bit serial.
Therefore, when it is not necessary to limit the number of input / output terminals, digital data may be input in bit parallel. In this case, the shift register 24 of the control unit 21b can be omitted.

<Third Embodiment> Next, the third embodiment of the present invention will be described.
Will be described. FIG. 9 shows a power supply control device (control unit 21c) according to the third embodiment of the present invention. The control unit 21c is premised on that the digital data of the external reference voltage value is composed of a bit string representing the external reference voltage Vref and one bit for selecting operation of the switch 22 (data for selecting operation). The parallel data output from the switch is input to the switch 22.

The switch 22 is adapted to detect 1 bit for selecting operation from parallel data. That is,
The switch 22 is provided with a function equivalent to that of incorporating the external input detecting means of the present invention. Then, the switch 22 selects the switching input terminal β when 1 bit for selecting operation is not detected or when the 1 bit for selecting operation is 0, and when the 1 bit for selecting operation is 1, the switching input terminal β is selected. It is designed to select γ. The other configurations are the same as the configurations of the second embodiment, and the description thereof will be omitted.

According to the control section 21c of the third embodiment, when digital data of the external reference voltage value is input, the digital data is converted by the shift register 24 into parallel data. This parallel data is input to the DAC 25 and the switch 22, and the DAC 2
5 converts the analog external reference voltage Vref.
On the other hand, the switch 22 detects one bit for selecting operation from this parallel data, and when it judges that this one bit is 1, it selects the switching input terminal γ. This allows the DAC25
The external reference voltage Vref converted by the error amplifier 6
Input to 1. Since the operation thereafter is the same as that of the second embodiment, the description thereof is omitted.

The effect of the third embodiment is almost the same as the effect of the second embodiment, but the comparator 23 and the comparison power supply 30 are omitted instead of adding the 1-bit detection function for the selection operation to the switch 22. can do.

The digital data input to the switch 22 may be serial data input from the terminal DI. Further, when the switch 22 detects one bit for selecting operation, the switching input terminal γ may be selected regardless of whether the one bit for selecting is 0 or 1. Furthermore, when the digital data of the external reference voltage value does not include 1 bit for the selection operation and the digital data of the external reference voltage value is input to the switch 22, the switch 22 detects this digital data and switches the input terminal. It is also possible to select γ.

Further, the above-mentioned first to third embodiments show the configuration in the case where the output voltage is changed from the original value to the + direction. In reality, however, since the change is also made in the − direction, a plurality of comparators 23 are provided or a logic circuit is provided so that the change can be made in both the + direction and the − direction.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.
An embodiment will be described. FIG. 10 shows a DC-DC converter 10 (corresponding to a power supply circuit) of a synchronous rectification system that uses the power supply control circuit according to the fourth embodiment as a control unit 21d. The DC-DC converter 10 has substantially the same configuration as the DC-DC converter 10 (see FIG. 5) according to the first embodiment. Therefore, the description of the common points is omitted, and the differences will be described.

The control section 21d is provided with an output terminal DH and an output terminal DL, and the output terminal DH is connected to the control end of the transistor Tr1 as in the first embodiment. On the other hand, the output terminal DL is connected to the control end of the transistor Tr2. The input end of the transistor Tr2 is connected between the output end of the transistor Tr1 and the choke coil L1, and the output end of the transistor Tr2 is grounded.

The transistor Tr2 is a so-called synchronous rectification transistor, and is a flywheel switch circuit for discharging the electric power accumulated in the choke coil L1 while the transistor Tr1 is OFF. The transistor Tr2 is ON / OFF controlled by the controller 21d. That is, the transistor Tr2 is turned on when the voltage applied to the flywheel diode D2 is in the forward direction, and is turned off when the voltage applied to the flywheel diode D2 is in the reverse direction. As a result, the voltage drop of the flywheel diode D2 is reduced. The transistor Tr2 is composed of an FET. Also,
The diode D1 provided between the choke coil L1 and the output terminal of the DC-DC converter 10 is removed.

Next, the internal structure of the controller 21d will be described with reference to FIG. The control unit 21d also has substantially the same configuration as the control unit 21a (see FIG. 6) according to the first embodiment.
Therefore, the description of the common points is omitted, and the differences will be described.

The control unit 21d is the control unit 2 shown in FIG.
The comparator 23, the comparison voltage source 30, and the resistor R4 are removed from 1a, and a charge pump circuit 67, a synchronous rectification control circuit 68, and a second drive circuit 69 are newly added. PWM comparator (corresponding to control signal generating means) 62
The output end of the drive circuit 65 and the synchronous rectification control circuit 6
8 is connected. As a result, the synchronous rectification control circuit 6
The PWM signal is input to the 8 from the PWM comparator 62.

The synchronous rectification control circuit 68 is a circuit for controlling ON / OFF of the transistor Tr2 so that synchronous rectification is performed. That is, O of the transistor Tr1
Transistor Tr2 turns OFF / ON at the same time as N / OFF
As described above, when the PWM signal input from the PWM comparator 62 is at the LOW level, the HIGH level P
When the WM signal and the PWM signal are at the HIGH level, the LOW level PWM signal is input to the second drive circuit 69 while adjusting the input timing.

The charge pump circuit 67 is connected to the drive circuit 65 and the second drive circuit 69. The charge pump circuit 67 is a power supply circuit that supplies the operating voltages of the transistors Tr1 and Tr2 to the drive circuit 65 and the second drive circuit 69.

The drive circuit 65 is connected to the control end of the transistor Tr1 via the terminal DH. The drive circuit 65 outputs the HIGH level PWM signal to the PWM
When received from the comparator 62, the voltage supplied from the charge pump circuit 67 is applied to the control end of the transistor Tr1 to turn on the transistor Tr1 for a predetermined time. The second drive circuit 69 includes the synchronous rectification control circuit 6
8 output terminals. The second drive circuit 69 is connected to the control end of the transistor Tr2 via the terminal DL. This second drive circuit 69 is
When the GH level PWM signal is received from the synchronous rectification control circuit 68, the voltage supplied from the charge pump circuit 67 is applied to the control end of the transistor Tr2. As a result, the transistor Tr2 is turned on for a predetermined time based on the PWM signal. The switch 22 is adapted to be manually selected.

DC-D equipped with such a control unit 21d
Similarly to the first embodiment, the C converter 10 is also mounted on an electronic device (not shown) and supplies an operating voltage to a load (not shown) of the electronic device. Below, DC installed in electronic equipment
-Examples of using the DC converter 10 will be described for a case where an electronic device is normally used and a case where a margin test is performed. (1) Normal use of electronic device As a premise, the operator tilts the switch 22 shown in FIG. 11 to the switching input terminal β side, and the DC-shown in FIG.
The input voltage Vi is applied to the input terminal of the DC converter 10, and an ON signal is input to the control unit 21d.

Then, power is supplied to the power source 63 of the control unit 21d, and an ON signal is input. The power supply 63 supplies power to each unit of the control unit 21d according to the ON signal. Then, the triangular wave oscillator 64 outputs a triangular wave signal. Further, the charge pump circuit 67 supplies a voltage to the drive circuit 65 and the second drive circuit 69. Further, the comparison voltage source 30 inputs the comparison voltage e2 to the comparator 23.

On the other hand, as described above, since the switch 22 is in the state where the switch input terminal β is selected, the internal reference voltage e1 is input from the built-in reference voltage source 66 to the error amplifier 61. However, since the output voltage Vo is not detected at this time, the voltage zero is input to the error amplifier 61 as the control voltage ERR.

The error amplifier 61 compares the internal reference voltage e1 with the control voltage ERR, detects and amplifies these errors, and inputs the result as an output signal to the PWM comparator 62. On the other hand, the PWM comparator 62 includes a triangular wave oscillator 64
A triangular wave signal is input from. The PWM comparator 62 compares the output signal of the error amplifier 61 and the triangular wave signal, and the value of the control voltage ERR is zero. Therefore, since the triangular wave signal is higher than the output signal of the error amplifier 61, the PWM signal of HIGH level is output. The signal is input to the drive circuit 65 and the synchronous rectification control circuit 68.

The drive circuit 65 has a high-level P
When receiving the WM signal, the transistor Tr1 shown in FIG. 10 is turned on based on the PWM signal by using the voltage supplied from the charge pump circuit 67. On the other hand, when the synchronous rectification control circuit 68 receives the high-level PWM signal, the synchronous rectification control circuit 68 generates a LOW signal, and the transistor Tr1
Is input to the second drive circuit 69 in consideration of the ON time. When receiving the LOW level signal, the second drive circuit 69 uses the voltage supplied from the charge pump circuit 67 to turn off the transistor Tr2 shown in FIG. 10 based on the PWM signal. As a result, the transistor Tr1 is turned on and at the same time the transistor Tr2 is
Is turned off, the transistor Tr1 is turned off, and at the same time, the transistor Tr2 is turned on.

While the transistor Tr1 is ON, a voltage is applied to the output end of the transistor Tr1 and power is stored in the choke coil L1. When the transistor Tr1 is turned off, the transistor Tr2 is turned on at the same time. Then, by the flywheel diode D2,
The electric power stored in the choke coil L1 is released. As a result, the output voltage Vo having a value based on the internal reference voltage e1 is output to the output terminal of the DC-DC converter 10.

The output voltage Vo is input to the control section 21d from the terminal FB at any time, and is detected as the control voltage ERR by the resistors R1 and R2 shown in FIG. The control voltage ERR is input to the error amplifier 61. Then, the error amplifier 61 uses the control voltage ER
The result of detection and amplification of the difference between R and the internal reference voltage e1 is P
Input to the WM comparator 62.

The PWM comparator 62 compares the output signal of the error amplifier 61 with the triangular wave signal to generate a PWM signal of HIGH level or LOW level, and the drive circuit 6
5 and the synchronous rectification control circuit 68. Then, the drive circuit 65 and the second drive circuit turn on the transistors Tr1 and Tr2 based on the PWM signal.
N / OFF. Such an operation is repeated.

As described above, the controller 21d controls the output voltage V
o is monitored, and when the value of the output voltage Vo decreases, the output voltage V
The transistor Tr1 and the transistor Tr2 are turned on / off so that o becomes a voltage value substantially matching the internal reference voltage e1.
Control OFF. As a result, the output voltage Vo having a value based on the internal reference voltage e1 is constantly output to the output terminal of the DC-DC converter 10 and supplied to the load as an operating voltage, so that the load operates normally. (2) When performing a margin test When performing a margin test, as a premise, the operator tilts the switch 22 shown in FIG. 11 to the switching input terminal γ side to input the DC-DC converter 10 shown in FIG. An input voltage Vi is applied to the end and the control unit 21d
Input ON signal to. Further, an external reference voltage Vref for margin test is applied from the terminal OSV.

Then, the power supply 63 supplies electric power to each part of the control section 21d according to the ON signal, and the triangular wave oscillator 64 inputs the triangular wave signal to the PWM comparator 62. Further, the charge pump circuit 67 is connected to the drive circuit 6
5 and a voltage are supplied to the second drive circuit.

Since the switch 22 is in a state in which the switching input terminal γ is selected, the external reference voltage Vre
f is input to the error amplifier 61. On the other hand, the control voltage E
Since the output voltage Vo of the RR cannot be detected at this time point, a voltage of zero is input to the differential voltage unit 61 as the control voltage ERR. Subsequent operations are the same as in the case of using the electronic device normally, and thus the description thereof is omitted. Finally, the output voltage Vo based on the external reference voltage Vref is constantly output to the output terminal of the DC-DC converter 10. After the margin test, the operator selects the switch 2
When 2 is tilted to the switching input terminal β side, the electronic device is ready for shipment.

The effects of the power supply control device according to the fourth embodiment are almost the same as the effects of the first embodiment. However,
Since the selection operation of the switch 22 according to the present embodiment is performed manually, the number of steps in the margin test is increased as compared with the first embodiment.

In the first to fourth embodiments, the input voltage Vi may be used as it is as the drive voltage of the control section, or the input voltage Vi may be measured and used. Further, although the DC-DC converter 10 is shown as the power supply circuit, the power supply circuit to which the power supply control device of the present invention is applied is not limited to this, and can be similarly applied to a series regulator or the like.

[0129]

As described above, according to the power supply control device and the load test method of the present invention, by providing the selector, the output voltage of the power supply circuit can be easily changed without attaching or detaching the constituent elements of the power supply circuit. . Therefore, it is possible to save labor in the margin test (load test), and it is also possible to perform the margin test for all electronic devices equipped with the power supply circuit. Further, the margin test can be further saved by automatically performing the selecting operation of the selector. Further, there is an advantage that the external reference voltage can be programmed, which is effective when, for example, the battery voltage is monitored by software.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of an embodiment of the present invention.

FIG. 3 is a block diagram showing an outline of an embodiment of the present invention.

FIG. 4 is a block diagram showing an outline of an embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a DC-DC converter using the power supply control device according to the first embodiment of the present invention.

FIG. 6 is an internal configuration diagram of the power supply control device (control unit) shown in FIG.

FIG. 7 is an overall configuration diagram of a DC-DC converter using a power supply control device according to a second embodiment of the present invention.

8 is an internal configuration diagram of the power supply control device (control unit) shown in FIG.

FIG. 9 is an internal configuration diagram of a power supply control device (control unit) according to a third embodiment of the present invention.

FIG. 10 is an overall configuration diagram of a DC-DC converter using a power supply control device according to a fourth embodiment of the present invention.

11 is an internal configuration diagram of the power supply control device (control unit) shown in FIG.

FIG. 12 is an overall configuration diagram of a DC-DC converter using a conventional power supply control device.

13 is an internal configuration diagram of the power supply control device (control unit) shown in FIG.

14 is an overall configuration diagram of the DC-DC converter shown in FIG. 12 during a margin test.

FIG. 15 is an overall configuration diagram of a DC-DC converter using a conventional power supply control device.

16 is an internal configuration diagram of the power supply control device (control unit) shown in FIG.

[Explanation of symbols]

R1, R2 resistors (output voltage detecting means) Vo output voltage e1 internal reference voltage (reference voltage) Vref external reference voltage 10 DC-DC converter (power supply circuit) 21a, 21b, 21c, 21d control unit (power supply control device) 22 Switch 23 Comparator (external input detection means) 24 DAC (digital-analog converter) 30 Comparison voltage source 61 Error amplifier (comparison (comparison) means) 62 PWM comparator (control signal generation means) 66 Built-in reference voltage source

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidetoshi Yano 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (72) Inventor Hidekiyo Ozawa 4-chome, Ueodaanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture No. 1 within Fujitsu Limited

Claims (23)

[Claims] 1. An output voltage detecting means for detecting an output voltage of a power supply circuit, and a built-in reference voltage source for supplying a reference voltage, the output voltage detected by the output voltage detecting means and the built-in reference voltage source. In the power supply control device that compares the supplied reference voltage and outputs a control signal that constantly controls the output voltage of the power supply circuit based on the result of this comparison, the output detected by the output voltage detection means. A power supply control comprising a selector that selects one of the reference voltage supplied from the built-in reference voltage source and an external reference voltage externally applied to the power supply control device as a voltage to be compared with the voltage. apparatus. 2. An external input detection means for detecting whether or not the external reference voltage is applied, wherein the selector is one of the reference voltage and the external reference voltage based on a detection result of the external input detection means. 2. The power supply control device according to claim 1, wherein is selected. 3. An output voltage detecting means for detecting an output voltage of a power supply circuit, and a built-in reference voltage source for supplying a reference voltage, wherein the output voltage detected by the output voltage detecting means and the built-in reference voltage source are supplied. In the power supply control device that outputs a control signal that controls the output voltage of the power supply circuit based on the result of the comparison, the digital data of the external reference voltage input from the outside. To an analog external reference voltage, and a reference voltage supplied from the built-in reference voltage source as the voltage to be compared with the output voltage detected by the output voltage detection means, and the digital / analog converter. A power supply control device comprising: a selector that selects one of the external reference voltage converted by the converter. 4. An external input detection means for detecting whether or not the external reference voltage is applied, wherein the selector is one of the reference voltage and the external reference voltage based on a detection result of the external input detection means. 4. The power supply control device according to claim 3, wherein 5. The external input detection means detects the analog external reference voltage converted by the digital-analog converter, and the selector determines the reference based on the detection result of the external input detection means. The power supply control device according to claim 4, wherein one of a voltage and the external reference voltage is selected. 6. The external input detection means detects digital data of the external reference voltage input to the digital-analog converter, and the selector, based on a detection result of the external input detection means. The power supply control device according to claim 4, wherein one of a reference voltage and the external reference voltage is selected. 7. Digital data of the external reference voltage includes data for selecting operation of the selector, the selector detects data for selecting operation of the selector, and based on the data for selecting operation of the selector. The power supply control device according to claim 3, wherein one of the reference voltage from the built-in reference voltage source and the external reference voltage converted by the digital-analog converter is selected. 8. An output voltage detecting means for detecting an output voltage of a power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and a selection for comparing with the control voltage detected by the output voltage detecting means. A selector for selecting one of the internal reference voltage supplied from a built-in reference voltage source and the external reference voltage applied from the outside as a reference voltage;
For adjusting the output voltage of the power supply circuit to a voltage according to the selection reference voltage based on a comparison result of the control voltage detected by the output voltage detection means and the selection reference voltage selected by the selector A load test method for testing the operation of a load connected to the power supply circuit, using a power supply control device comprising a control signal generating means for generating a control signal, wherein the power supply is used when testing the operation of the load. The output voltage of the power supply circuit adjusted to a voltage according to the external reference voltage by applying the external reference voltage to the control device from the outside and causing the selector to select the external reference voltage as the selection reference voltage. Is supplied to the load. 9. The power supply control device is provided with an external input detection means for detecting whether or not the external reference voltage is applied, and the selector uses the external reference voltage as the selection reference based on a detection result of the external input detection means. The load test method according to claim 8, wherein the load test method is selected as a voltage. 10. The value of the output voltage of the power supply circuit supplied to the load is changed by changing the value of the external reference voltage applied to the power supply control device. Load test method described. 11. An output voltage detecting means for detecting an output voltage of a power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and digital data of an external reference voltage input from the outside as an analog external reference. A digital-to-analog converter for converting into a voltage, and the internal reference voltage supplied from a built-in reference voltage source as the selected reference voltage to be compared with the control voltage detected by the output voltage detecting means, and the digital-to-analog converter. A selector that selects one of the converted external reference voltage; and a selector for the power supply circuit based on a comparison result of the control voltage detected by the output voltage detection means and the selected reference voltage selected by the selector. A control signal generator for generating a control signal for adjusting the output voltage to a voltage according to the selected reference voltage. Using a power supply control device having a step,
A load test method for testing an operation of a load connected to the power supply circuit, wherein when the operation of the load is tested, the digital data of the external reference voltage is externally input to the power supply control device, and A load test method comprising supplying the output voltage of the power supply circuit adjusted to a voltage according to the external reference voltage to the load by causing a selector to select the external reference voltage as the selection reference voltage. 12. The power supply control device is provided with an external input detection means for detecting whether or not the external reference voltage is applied, and the selector is based on a detection result of the external input detection means.
The load test method according to claim 11, wherein the external reference voltage is selected as the selection reference voltage. 13. The external input detecting means detects the analog external reference voltage converted by the digital-analog converter, and the selector outputs the external signal based on the detection result of the external input detecting means. 13. The load test method according to claim 12, wherein a reference voltage is selected as the selected reference voltage. 14. The external input detection means detects the digital data of the external reference voltage input to the digital-analog converter, and the selector is based on the detection result of the external input detection means. The load test method according to claim 12, wherein an external reference voltage is selected as the selected reference voltage. 15. Digital data of the external reference voltage includes data for selecting operation of the selector, the selector detects data for selecting operation of the selector, and based on the data for selecting operation of the selector. ,
The load test method according to claim 11, wherein the external reference voltage converted by the digital-analog converter is selected as the selection reference voltage. 16. The value of the output voltage of the power supply circuit supplied to the load is changed by changing the digital data of the external reference voltage. Load test method. 17. An output voltage detecting means for detecting an output voltage of a power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and a selection for comparing with the control voltage detected by the output voltage detecting means. A selector that selects one of the internal reference voltage supplied from the built-in reference voltage source and an external reference voltage source applied from the outside as a reference voltage, the control voltage detected by the output voltage detection means, and the selector. Control signal generating means for generating a control signal for adjusting the output voltage of the power supply circuit to a voltage according to the selection reference voltage based on the comparison result with the selection reference voltage selected by A power supply control device characterized by being provided inside an integrated circuit. 18. An external input detection means for detecting whether or not the external reference voltage is applied is further provided, and the selector selects the internal reference voltage and the external reference voltage based on a detection result of the external input detection means. The power supply control device according to claim 17, wherein one is selected. 19. An output voltage detection means for detecting an output voltage of a power supply circuit as a control voltage, a built-in reference voltage source for supplying an internal reference voltage, and digital data of an external reference voltage input from the outside as an analog external reference. A digital-to-analog converter for converting into a voltage, the internal reference voltage supplied from the built-in reference voltage source as the selected reference voltage to be compared with the control voltage detected by the output voltage detecting means, and the digital-to-analog converter A selector for selecting one of the external reference voltage converted by
For adjusting the output voltage of the power supply circuit to a voltage according to the selection reference voltage based on a comparison result of the control voltage detected by the output voltage detection means and the selection reference voltage selected by the selector A power supply control device comprising: a control signal generating means for generating a control signal in a single integrated circuit. 20. An external input detection means for detecting whether or not the external reference voltage is applied is further provided, and the selector selects the internal reference voltage and the external reference voltage based on a detection result of the external input detection means. The power supply control device according to claim 19, wherein one is selected. 21. The external input detection means detects the analog external reference voltage converted by the digital-analog converter, and the selector outputs the internal reference voltage based on a detection result of the external input detection means. The power supply control device according to claim 20, wherein one of a reference voltage and the external reference voltage is selected. 22. The external input detection means detects digital data of the external reference voltage input to the digital-analog converter, and the selector, based on a detection result of the external input detection means. The power supply control device according to claim 20, wherein one of an internal reference voltage and the external reference voltage is selected. 23. Digital data of the external reference voltage includes data for selecting operation of the selector, the selector detects data for selecting operation of the selector, and based on the data for selecting operation of the selector. 20. The power supply control device according to claim 19, wherein one of the internal reference voltage from the built-in reference voltage source and the external reference voltage converted by the digital-analog converter is selected.