JPH05191970A - Power supply - Google Patents

Abstract

PURPOSE:To obtain secondary output voltages of more than one system without enlarging the scale of a circuit by forming a charge pump of a capacitor and a diode and employing the output from a booster coil as a switching signal in a switching regulator comprising the booster coil and a transistor. CONSTITUTION:An input voltage VIN is fed through a booster choke coil L1 to a FET Q1 and through a diode D1 to a smoothing filter 2. The transistor Q1 operates with a switching pulse PSW fed from a PWM circuit 3 and outputs a first secondary output voltage VOUT1 through the smoothing filter 2. Thus the smoothed voltage is fed through a control circuit 6 back to the PWM circuit 3. A second secondary output voltage VOUT2 is obtained by providing a charge pump type DC-DC converter comprising diodes D5, D6 and capacitors C20, C30 and employing the output of the booster choke coil L1 as a switching signal for the capacitor 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, and is particularly applicable to a high frequency chopper type switching regulator structure.

[0002]

2. Description of the Related Art Conventionally, as a power supply device for obtaining a power supply voltage (for example, 5 [V]) for an integrated circuit from one dry battery of, for example, 1.5 [V], a so-called high-frequency step-up chopper type switching regulator structure is used. There is.

Further, as a method for realizing a DC-DC converter without using windings such as a coil and a transformer, there is a so-called charge pump method (or a switched capacitor method), which is generally widely used. Has been done.

On the other hand, in a switching regulator using a coil or a transformer, when a desired secondary output voltage is required, for example, two or more systems, a device having a buck-boost function dedicated to each system is prepared. If the required voltage is an integral multiple of the other voltage, the charge pump method (switched capacitor method) that can realize the DC-DC converter in the simplest case may be used. Many.

FIG. 5 shows the configuration of a conventional power supply device. That is, in this conventional power supply device 1, the primary voltage V _IN (for example, 1 [V] or 1.5 [V]) input from the dry battery (not shown) is transferred to the N channel through the boosting choke coil L1. It is supplied to the drain of the switching transistor Q1 formed of a field effect transistor (FET), and is also supplied to the smoothing filter 2 formed of the coil L2 and the capacitors C1 and C2 through the free wheeling diode D1 connected in the forward direction.

Here, the source of the transistor Q1 is grounded, and the switching pulse P _SW generated in the pulse width modulation (PWM) circuit 3 is input to the gate, whereby the transistor Q1 responds to the switching pulse P _SW. Switching operation is performed to form a boost chopper.

As a result, the smoothed voltage after being boosted is output through the smoothing filter 2, and this is output as the secondary side output voltage V _OUT1 as required.

In this power supply device 1, a feedback loop for feeding back the smoothed voltage to the PWM circuit 3 via the control circuit 6 is constructed, and the control circuit 6 performs the PWM based on the fed back smoothed voltage. By controlling the circuit 3, the switching pulse P _SW is generated from the PWM circuit 3 at a duty ratio that stabilizes the smoothed voltage, and a stabilized power supply is obtained.

By the way, when the desired secondary output voltage is required, for example, in two or more systems (for example, when the required voltage may be an integral multiple of another voltage), the above-described conventional power supply device 1 has The secondary side output voltage V _OUT1 (hereinafter referred to as the first secondary side output voltage V _OUT1 ) is obtained, and as described above, the charge pump method (switched capacitor method) is used to obtain the second secondary side voltage. Output voltage V _OUT2 (for example, about 10 [V] of the above-mentioned first secondary side output voltage V _OUT1 × 2)
Trying to get.

That is, in the conventional power supply device 1 shown in FIG. 5, diodes D5 and D6 and a capacitor C2 are provided as a structure for obtaining the second secondary side output voltage V _OUT2.
So-called charge pump type DC-D consisting of 0 and C30
A C converter is provided, and further, for example, the above capacitor C2
It has an inverter IC5 for switching 0 and an oscillator 16 for switching the inverter IC5. The first secondary output voltage V _OUT1 is supplied to these configurations to obtain the second secondary output voltage V _OUT2 .

Explaining the configuration in detail, the first secondary side output voltage V _{OUT1 is} applied to the input terminal of the diode D5.
Is supplied, and the output terminal of the diode D5 is connected to the input terminal of the diode D6. The (+) side terminal of the capacitor 20 is the diode D5.
And D6, and the (-) side terminal is connected to the output terminal of the inverter IC5. Further, the output terminal of the diode D6 is connected to one end of the capacitor C30 whose other end is grounded.
And the voltage at the connection point between the capacitor C30 and
The secondary output voltage V _OUT2 is taken out.

Therefore, as the operation of the above configuration, for example, if the pulse from the switching signal generating means composed of the inverter IC 5 and the oscillator 16 is 0 [V] at a certain time, the (-) of the capacitor C 20 will be used. because the pulled even side terminal 0 V, the diode D5 is forward biased, 5 V -V _F is generated in this order of the capacitor C20 (+) terminal. Note that V _F is the forward voltage drop of the diode.
After that, if the pulse from the switching signal generating means changes from 0 [V] to 5 [V], the (-) side terminal of the capacitor C20 also changes from 0 [V] to 5 [V].
Since it changes in a pulse manner up to [V], the capacitor C
20 (+) terminal is further 5 V increases from the state of the previous 5 V -V _F (that is, 10 [V] -V _F). At this time, since the diode D20 is reverse biased and the diode D30 is forward biased, power is supplied only to the capacitor C30. From the above, the voltage of the capacitor C30 is 10 [V].
It will be stabilized at -2V _F.

The second secondary output voltage V
_OUT2 is also sent to the PWM circuit 3 and is used as a gate driving power source for the transistor Q1 of the switching FET in order to reduce the ON resistance of the transistor Q1.

[0014]

In the conventional power supply device having the above-mentioned structure, the second secondary side output voltage V
To obtain _OUT2 , the configuration of the charge pump type DC-DC converter, the inverter IC5 for switching the capacitor C20, and the oscillator 1 for switching the inverter IC5 are provided.
6 is required separately, resulting in an increase in circuit scale and an increase in current consumption.

Therefore, the present invention has been proposed in view of the above situation, and the target secondary output voltage is set to 2 without increasing the circuit scale and the current consumption.
It is an object of the present invention to provide a power supply device capable of obtaining more than one system.

[0016]

The power supply device of the present invention is proposed in order to achieve the above-mentioned object, and is a high frequency chopper type switching regulator, and is a boosting choke to which a primary voltage is supplied. A coil, a switching element that switches the voltage supplied from the boosting choke coil, and a smoothing unit that smoothes the voltage generated at the midpoint between the boosting choke coil and the switching element are provided. A power supply device for obtaining a boosted secondary voltage via a smoothing means, comprising: a first one-way conducting means for supplying a first secondary voltage from the smoothing means to an input terminal; The output terminal of the one-way conducting means is connected to the input terminal and the second one-way conducting means has one end connected to the midpoint of the first and second one-way conducting means, and the other end connected to the second one-way conducting means. A first capacitor connected to the point between the pressure choke coil and the switching element, an output terminal of the second one-way conducting means is connected to one end,
A second capacitor having the other end grounded, and the voltage at the connection point between the output terminal of the second one-way conducting means and the one end of the second capacitor is obtained as the second secondary voltage. It was done like this.

In other words, the power supply device of the present invention uses a capacitor and a diode (or a semiconductor switch) in addition to the intended secondary output voltage in a switching regulator using a coil or a transformer, and outputs the original secondary output voltage. It is a power supply circuit that can obtain another boosted voltage highly efficiently and easily by using the switching pulse of the coil or transformer that is generated in order to obtain a switching signal generating means that includes, for example, an inverter or an oscillator. It is possible to obtain a boosted voltage of another system only by using a capacitor and a diode without constructing.

Further, in the present invention, the drive voltage generating means for supplying the second secondary voltage and generating the switching drive voltage for switching the switching element based on the second secondary voltage. I also have.

[0019]

According to the power supply device of the present invention, since the output of the boosting choke coil is used as the switching signal (voltage) of the capacitor of the charge pump, the switching signal generating means of another system is unnecessary.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a power supply device 3 according to the first embodiment of the present invention.
The structure of 0 is shown. In FIG. 1, the same components as those in FIG. 5 described above are designated by the same reference numerals.

As shown in FIG. 1, the power supply device 30 of the present embodiment is a high frequency chopper type switching regulator, and is composed of a primary input voltage V _IN (for example, 1 [V] or 1.5 [V] of a dry battery). Boosting choke coil L
1, an N-channel field effect transistor (FET) Q1 which is a switching element for switching the voltage supplied from the boosting choke coil L1, and a midpoint between the boosting choke coil L1 and the transistor Q1. A smoothing filter 2 for smoothing the generated voltage is provided, and the voltage boosted by the smoothing filter 2
A diode that is a first one-way conduction means that obtains a secondary voltage and that is supplied with a secondary voltage from the smoothing filter 2 (hereinafter referred to as a first secondary-side output voltage V _OUT1 ) to an input terminal. D5, a diode D6 which is a second one-way conduction means in which an output terminal of the diode D5 is connected to an input terminal, and one end of which is connected to a connection midpoint of the diodes D5 and D6, and the other end of which is boosted Capacitor C20 which is a first capacitor connected to the middle point between the choke coil L1 and the transistor Q1, and a capacitor which is a second capacitor in which the output terminal of the diode D6 is connected to one end and the other end is grounded. C30, and the voltage at the connection point between the output terminal of the diode D6 and the one end of the capacitor C30 is set to another secondary voltage (hereinafter referred to as the second secondary side output voltage V _OUT2 And)).

In other words, the power supply device 30 of this embodiment
Is a capacitor (capacitors C20, C30) and a diode D in addition to the target secondary output voltage (first secondary-side output voltage V _OUT1 ) in the switching regulator using the boosting choke coil L1 (or transformer).
5, D6 (or semiconductor switch) is used to generate the switching pulse of the boosting choke coil L1 (or transformer) generated to obtain the original secondary output voltage (first secondary side output voltage V _OUT1 ). It is a power supply circuit that can obtain another boosted voltage (secondary secondary side output voltage V _OUT2 ) with high efficiency and easily by using the switching signal like the conventional example of FIG. The capacitors C20, C30 and the diode D5 are not required to constitute the generating means.
It is possible to obtain the boosted voltage of another system (second secondary side output voltage V _OUT2 ) with only the configuration of D6.

The apparatus 30 of this embodiment is the same as the second
A secondary output voltage V _OUT2 is supplied and, for example, a level shifter 9 is also provided as a drive voltage generating means for generating a switching drive voltage for switching the transistor Q1 based on the second secondary output voltage V _OUT2. is doing.

The configuration and operation of FIG. 1 will be specifically described below.

This embodiment can be applied to, for example, a case where the input voltage of one dry battery is boosted to a voltage required for operating a microcomputer or the like.

In FIG. 1, the power supply device 3 according to the present embodiment.
At 0, a primary input voltage V _IN input from a dry cell (not shown) is supplied to the drain of the transistor Q1 through the boosting choke coil L1 and also through a freewheeling diode D1 connected in the forward direction. , Are supplied to the smoothing filter 2. The switching pulse P _SW generated by the PWM circuit 3 is input to the gate of the transistor Q1. As a result, the transistor Q1 performs a switching operation according to the switching pulse P _SW to form a boost chopper. As a result, the smoothed voltage after being boosted is output through the smoothing filter 2, and this is output as the first secondary side output voltage V _OUT1 (for example, 5 [V]) as necessary. Further, in this power supply device 30, a feedback loop for feeding back the smoothed voltage to the PWM circuit 3 via the control circuit 6 is configured, and the control circuit 6 performs the PWM circuit based on the fed back smoothed voltage. By controlling 3, the switching pulse P _SW is generated from the PWM circuit 3 at a duty ratio that stabilizes the smoothed voltage, and a stabilized power supply is obtained. The above configuration is similar to that of FIG. 5 described above.

In the device 30 of the present embodiment, when the target secondary output voltage is required, for example, in two or more systems (for example, when the required voltage is an integral multiple of another voltage),
About 10 of the first secondary output voltage V _OUT1 above the configuration as described below with reference to the second secondary output voltage V _OUT2 (e.g. the first secondary output voltage V _OUT1 × 2
[V]).

That is, both the device 30 of this embodiment and the conventional power supply device 1 shown in FIG. 1 described above have the above-mentioned diodes D5 and D6 and capacitors as a structure for obtaining the second secondary side output voltage V _OUT2. Although a so-called charge pump type DC-DC converter including C20 and C30 is provided, in the power supply device 30 of the present embodiment, the above-mentioned conventional device 1 of FIG. 5 is used as a switching signal for switching the capacitor C20. However, the pulse at the midpoint (terminal P2) between the boost choke coil L1 and the transistor Q1 is used. The second secondary output voltage V _OUT2 is obtained by supplying the first secondary output voltage V _OUT1 to the input terminal of the diode D5 having this configuration.

The operation of this configuration will be specifically described with reference to the timing chart of FIG.

That is, the operation of the configuration of the apparatus 30 of the present embodiment is, for example, time t1 as shown in A of FIG.
When the switching pulse P _SW becomes “H” and the transistor Q1 turns on at the timing of, the drain of the transistor Q1 (terminal P2
Side) becomes approximately 0 [V], and current is supplied from the primary input voltage V _IN to the boosting choke coil L1 until the transistor Q1 is turned off at the timing of time t2.

Between time t1 and time t2, since the diode D1 is reverse-biased, the voltage at the terminal P3 gradually drops as indicated by C in FIG. Also, from time t1
During the time t2, the (−) side terminal of the capacitor C20 is also pulled to 0 [V] by the transistor Q1.
The diode D5 is forward biased, and 5 [V] is applied to the (+) side terminal (terminal 5) of the capacitor C20.
-V _F occurs. Note that V _F is the forward voltage drop of the diode.

Next, when the switching pulse P _SW becomes "L" and the transistor Q1 is turned off at the timing of time t2, the counter electromotive voltage of the boosting choke coil L1 causes the terminal P2 to move to the position B in FIG. The voltage (5
[V] + V _F) to generate. Furthermore, time t2 to time t3
During the period, the diode D1 is forward biased and current is supplied from the boosting choke coil L1 toward the terminal P3, so that the voltage at the terminal P3 gradually rises as indicated by C in FIG.

As described above, by repeating the times t1 to t3, the voltage at the terminal 4 (secondary output voltage V _OUT1 ) is stabilized as shown by D in FIG.

Further, during the time t2~ time t3, the capacitor C20 (-) 5-side terminal from 0 [V] as shown in B of FIG. 2 [V] + V _F pulses varying due to , The (+) side terminal of the capacitor C20 is also 5 [V]-
From the state of V _F , it further rises by 5 [V] + V _F (that is, becomes 10 [V]). At this time, since the diode D5 is reverse biased and the diode D6 is forward biased, power is supplied only to the capacitor C30.

[0036] Thus, the voltage of the capacitor C30 (pin P6) is stabilized to 10 [V] -V _F.

From the above, in the device 30 of this embodiment, the diodes D5 and D7 and the capacitor C are
20 and C30 are added to the boost choke coil L1.
It is possible to obtain the boosted voltage of another system (the second secondary side output voltage V _OUT2 ) only by using the switching pulse of.

In the device 30 of the present embodiment, the second secondary output voltage V _OUT2 is used as a gate drive power source for the transistor Q1 in order to reduce the on-resistance of the transistor Q1 of the switching FET. ing.

That is, the second secondary side output voltage V
_OUT2 is sent to the level shifter 9. The level shifter 9 includes a comparator 91 to which the output of the PWM circuit 3 is supplied and NPN type transistors Q92 and PNP to which the output of the comparator 91 is supplied to the base.
Type transistor Q93, and the transistor Q9
The midpoint of the connection of 2, 93 is connected to the gate of the transistor Q1. The signal sent to the transistor Q1 is the switching pulse P _SW in this embodiment.

As described above, the device 30 of the first embodiment differs from the device 1 of the prior art shown in FIG.
Since a separate circuit such as switching signal generation means is not required,
The circuit scale is small and the current consumption is small.

Further, according to the first embodiment, the voltage obtained as the second secondary side output voltage V _OUT2 is 10 [V] −2V _F in the conventional device 1 described above. in this embodiment the circuit 30 for, 10 [V] -V _F becomes, the voltage drop is less efficient. The reason why the voltage drop is small is that the voltage higher than the voltage drop of the diode D1 is supplied from the boosting choke coil L1 in the configuration of the charge pump of this embodiment. That is, in the apparatus 30 of the present embodiment, the conventional apparatus 1
Of the boosting choke coil L having a higher amplitude than the pulse generated by the oscillator 16 (the oscillator 16 does not completely swing from 0 [V] to 5 [V] even at the maximum amplitude).
Since the signal from No. 1 is used as the switching signal of the charge pump, efficient boosting is possible.
As a result, the second secondary output voltage V _OUT2 also becomes higher than in the conventional example, and the gate voltage sent to the transistor Q1 is also advantageous.

FIG. 3 shows a second embodiment device 40 of the present invention.
Shows the configuration of. In FIG. 3 in which parts corresponding to those in FIG. 1 are denoted by the same reference numerals, diodes D7, D8 and capacitors C21, C31 forming a charge pump are added to the embodiment device 30 of FIG. The first secondary side output voltage V _OUT1 and the second secondary side output voltage V _OUT2
(V _OUT1 × 2) as well as the third secondary side output voltage V
A boosted voltage of _OUT3 (V _OUT1 × 3) can also be obtained.

That is, in the configuration of FIG. 3, the diodes D5 and D6 and the capacitor C20 of FIG.
By supplying the output of the charge pump composed of C30 (the second secondary output voltage V _OUT2 ) to the charge pump composed of the diodes D7 and D8 and the capacitors C21 and C31 having the same configuration, It is possible to obtain the third secondary side output voltage V _OUT3 .

In the configuration of FIG. 3, if the charge pump is further configured in multiple stages, it becomes possible to obtain a higher voltage.

FIG. 4 shows a third embodiment device 50 of the present invention.
Shows the configuration of. In FIG. 4 in which parts corresponding to those in FIG. 1 are denoted by the same reference numerals, the transistor Q1 of the FET of the embodiment device 30 of FIG. 1 is replaced with a bipolar transistor Q10, and diodes D5 and D6 are replaced with semiconductor switches SW10, This is an example using SW20, which is easily applied when it is integrated into an IC.

Here, in the case of the configuration of the embodiment of FIG. 4, since the semiconductor switches SW10 and SW20 are bidirectionally conductive when turned on, similar to the diodes D5 and D6 of the first and second embodiments. In order to use it as a one-way conducting element, the semiconductor switches SW10, SW20
The timing of turning on is synchronized with the timing of turning on the choke coil L1. That is, the inverter I
The signal that controls C6 is synchronized with the signal that turns transistor Q10 on and off. In this case, the duty ratio of ON / OFF does not necessarily have to be 50% as in the conventional example. Specifically, when the transistor Q10 turns on, the switch SW1 turns on (switch SW2 turns off), and when the transistor Q10 turns off, the switch SW2 turns on (switch SW1).
Off).

In the embodiment of FIG. 4, the transistor Q1
Although 0 is used, a field effect transistor may be used as in the above-mentioned embodiments. If a bipolar transistor is used as in this embodiment, a voltage of, for example, 10 [V] for lowering the on-resistance as in the case of using an FET is unnecessary, and therefore, according to the configuration of the third embodiment. , The second secondary side output voltage V as shown in FIGS.
You do not have to return _OUT2 .

In the device 50 of the third embodiment, I
It becomes easy to convert to C, and further, the above switches SW10, SW
If the ON resistance of 20 is low, the voltage loss corresponding to the voltage drop of the diodes D5 and D6 as in the first and second embodiments is eliminated.

[0049]

As described above, in the power supply device of the present invention, only by adding the capacitor and the one-way conducting means,
The boosted voltage of another system can be obtained most easily (two or more secondary side output voltages can be obtained), and the circuit scale does not increase. Further, since the switching pulse of the boosting choke coil is used as the switching signal of the charge pump, the power consumption is smaller than that in the case where a new switching signal generating means is provided, which is advantageous in terms of the boosting effect. Furthermore, the number of pins can be reduced even when integrated into a circuit, and it is particularly useful when, for example, a boosted voltage is required for the gate drive circuit in order to reduce the ON resistance of the FET.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of a power supply device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of each part of the configuration of this embodiment.

FIG. 3 is a circuit diagram showing a schematic configuration of a power supply device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a schematic configuration of a power supply device according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a conventional power supply device.

[Explanation of symbols]

 30 ... Power supply circuit 2 ... Smoothing filter 3 ... PWM circuit 6 ... Control circuit 9 ...・ ・ ・ Level shifter Q1 ・ ・ ・ Field effect transistors D1, D5, D6 ・ ・ Diodes C1, C2, C20, C30 ・ ・ Capacitor L1 ・ ・ ・ ・ ・ ・ Step-up choke coil

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[Procedure amendment]

[Submission date] July 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

That is, the second secondary output voltage V
_OUT2 is sent to the level shifter 9. The level shifter 9 includes a comparator 91 and field effect transistors Q94, Q95, Q96, Q97. Here, the output of the PWM circuit 3 is supplied to the input terminal of the comparator 91, and the comparator 9
The output terminal of 1 and the gate of the transistor Q95 are connected. The sources of the transistors Q95 and Q96 are grounded, the drain of the transistor Q95 is connected to the drain of the transistor Q94, and the transistor Q96 is connected to the drain of the transistor Q96.
Is connected to the drain of the transistor Q97. The connection middle point between the drains of the transistors Q94 and Q95 is connected to the gate of the transistor Q97, and the connection middle point between the drains of the transistors Q97 and Q96 is connected to the gate of the transistor Q94.
Furthermore, the sources of the transistors Q94 and Q97 are both connected to a 10V voltage source,
The gate of 96 is connected to the input terminal of the comparator 91. Furthermore, the transistors Q97 and Q
The midpoint of the connection between the drains of 96 is the transistor Q1.
Connected with the gate of. The signal sent to the transistor Q1 is the switching pulse P _SW in this embodiment.
Has become.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (2)

[Claims] 1. A high-frequency chopper-type switching regulator, which is a boosting choke coil to which a primary voltage is supplied, a switching element which switches the voltage supplied from the boosting choke coil, and the boosting choke coil. A smoothing means for smoothing the voltage generated at the midpoint of the switching element is provided, and a power supply device for obtaining a boosted secondary voltage via the smoothing means is provided. First unidirectional conducting means for supplying a next voltage to an input terminal; second unidirectional conducting means for connecting an input terminal to an output terminal of the first unidirectional conducting means; A first capacitor whose one end is connected to the midpoint of the second one-way conducting means and whose other end is connected to the midpoint between the boosting choke coil and the switching element; An output terminal of the second one-way conducting means has a second capacitor connected to one end and the other end of which is grounded, the output terminal of the second one-way conducting means and the second capacitor of the second capacitor. A power supply device, wherein a voltage at a connection point with the one end is obtained as a second secondary voltage. 2. A drive voltage generating means for generating a switching drive voltage for switching the switching element based on the second secondary voltage when the second secondary voltage is supplied. The power supply device according to claim 1.