JP4062962B2 - Semiconductor device and power supply device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device for voltage detection. In particular, the present invention relates to an output voltage detection semiconductor device used in an output voltage detection circuit unit of a power supply device (such as a switching power supply).
[0002]
[Prior art]
FIG. 10 is a configuration diagram of a voltage detection circuit used for the secondary output of the conventional power supply apparatus. FIG. 11 is an operation waveform diagram for explaining the circuit operation of the conventional voltage detection circuit shown in FIG. 10, and FIG. 12 is a circuit configuration diagram of a power supply device using the conventional voltage detection circuit.
[0003]
As shown in FIG. 10, the conventional voltage detection circuit divides the voltage of the VOUT terminal 13 by resistors 35 and 36 and detects it by the shunt regulator 33. A capacitor 14 is connected to the VOUT terminal 13, and the voltage at the VOUT terminal 13 rises when electric charge is supplied to the capacitor 14 from the outside. Further, the detection voltage level VO at the VOUT terminal 13 is determined by the following expression based on the threshold voltage Vth of the shunt regulator 33, the resistance value R35 of the resistor 35, and the resistance value R36 of the resistor 36.
[0004]
VO = Vth · (R35 + R36) / R35
In order to stably control the detection voltage level VO, the following measures are necessary.
(1) A resistor 37 and a capacitor 38 are connected in series as shown in FIG.
(2) In order to stabilize the detection voltage level, the detection current value to the shunt regulator is increased by additionally connecting a resistor 34 as shown in FIG.
[0005]
FIG. 11 shows waveforms of the current I33 flowing through the VOUT terminal 13, VO, and the shunt regulator 33 of the voltage detection circuit of FIG. The ripple voltage at the VOUT terminal 13 is determined by the time constant of the resistor 37 and the capacitor 38 (because it is necessary to have hysteresis characteristics).
[0006]
FIG. 12 is a diagram showing a circuit configuration of a power supply device using the conventional voltage detection circuit shown in FIG. 10 as a secondary side voltage detection circuit. A photocoupler 17 is used as the detection signal transmission means. When the voltage is detected by the conventional voltage detection circuit of FIG. 10, the shunt regulator 33 becomes conductive, so that a current flows through the light emitting portion 17a of the photocoupler 17 to emit light (output of a detection signal). The detection signal output by the light emission is detected by the light receiving unit 17b of the photocoupler 17, and the on / off control of the switching element 27 by the control circuit 26 on the primary side is stopped (or stopped). As a result, the energy supply from the primary side to the secondary side stops (or pauses), and the voltage at the VOUT terminal 13 gradually decreases. When the detection voltage level or lower is reached, the output of the detection signal from the photocoupler 17 and the shunt regulator 33 is lost, so that the on / off control of the switching element 27 by the control circuit 26 is resumed and energy is supplied from the primary side to the secondary side. The As a result, the voltage at the VOUT terminal 13 increases. Since the ripple voltage at the VOUT terminal 13 depends on the time constants of the resistor 37 and the capacitor 38, it varies depending on the load state of the VOUT terminal 13.
[0007]
[Problems to be solved by the invention]
The conventional voltage detection circuit has the following problems.
(1) In order to increase the detection voltage accuracy, it is necessary to increase the current value of the current I33 flowing through the shunt regulator 33. The current flowing at the time of detection is generally on the order of several mA. For this reason, it becomes a hindrance to high efficiency (that is, energy saving) which is currently regarded as a global approach.
(2) When the current value of the current I33 flowing through the shunt regulator 33 is insufficient, the detection voltage accuracy is deteriorated. Therefore, it is necessary to add a resistor 34.
(3) Since the voltage control of the VOUT terminal 13 depends on the time constants of the resistor 37 and the capacitor 38, the ripple voltage width of the VOUT terminal 13 varies greatly depending on the state of the load.
(4) The number of parts constituting the voltage detection circuit is large, and at least 8 points are required as shown in FIG.
[0008]
[Means for Solving the Problems]
A first semiconductor device according to the present invention has one end connected to an output voltage terminal (Vout) for detecting voltage , the other end connected to a reference voltage terminal, and the reference voltage terminal A connected first constant current source, a second constant current source, and a start / stop circuit; a NAND circuit having the other end of the start / stop circuit connected to a first input terminal; and the first A current mirror circuit comprising a constant current source, a first switch element and a second switch element, and a detection signal output terminal for transmitting a detection signal to the output terminal of the first switch element; A third switch element connected between the first constant current source of the current mirror circuit and the second switch element and having a control terminal to which an output terminal of the NAND circuit is connected; Second constant power A fourth switch element connected to the source, the other end connected to the voltage detection terminal, and a control terminal connected to the output terminal of the NAND circuit; the voltage detection terminal as the detection terminal; and a reference terminal And a comparator having an output terminal connected to a second input terminal of the NAND circuit.
[0009]
A second semiconductor device of the present invention includes a regulator having one end connected to an output voltage terminal (Vout) for detecting a voltage and the other end connected to a reference voltage terminal, and the reference voltage A first constant current source, a second constant current source, a third constant current source, and a start / stop circuit connected to the terminal, and the other end of the start / stop circuit is connected to the first input terminal; A NAND circuit, a third constant current source, a first switch element, and a second switch element, and a detection signal output terminal for transmitting a detection signal to the output terminal of the first switch element And a third switch element having a control terminal connected between the first constant current source and the second switch element and connected to the output terminal of the NAND circuit. , One end of the second constant current A fourth switch element having the other end connected to the voltage detection terminal and a control terminal connected to the output terminal of the NAND circuit, the voltage detection terminal serving as a detection terminal, and a reference terminal A reference voltage source is connected, and an output terminal has a comparator connected to the second input terminal of the NAND circuit.
[0010]
The first and second semiconductor devices preferably include at least five terminals of a ground terminal, a connection terminal, a reference voltage terminal, a voltage detection terminal, and a detection signal output terminal.
[0011]
The first voltage detection circuit of the present invention includes a first resistor connected between a connection terminal and a voltage detection terminal of the first and second semiconductor devices of the present invention, and the voltage detection terminal and the ground terminal. A second resistor connected in between, a first capacitor connected between a reference voltage terminal and a ground terminal, a second capacitor connected between the connection terminal and the ground terminal, and a detection signal output terminal It has the voltage detection signal transmission means connected.
[0012]
As described above, by configuring the voltage detection circuit using the first and second semiconductor devices of the present invention, the number of component parts can be reduced (the above-mentioned conventional example has eight points, but will be described later). In this embodiment, the number is 6 points, which is a reduction of 2 points).
[0013]
Further, when a voltage is detected by the first resistor and the second resistor, a current is supplied from the second constant current source to the resistor 2, so that the voltage at the output voltage terminal (Vout) for which the voltage is detected is small. It has a hysteresis characteristic by lifting up. Since the raised voltage width becomes the ripple voltage width, the ripple voltage width is always constant regardless of the load state of the output voltage terminal (Vout) whose voltage is detected .
[0014]
Further, the detection current passed through the first switch element connected to the detection signal output terminal in the first and second semiconductor devices of the present invention is composed of the first switch element and the second switch element. Since it can be adjusted by the mirror ratio of the current mirror circuit, a reduction in current can be realized.
[0015]
A first power supply device of the present invention is characterized in that the first voltage detection circuit of the present invention is used for an output voltage detection unit.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0017]
FIG. 1 shows a semiconductor device according to the first embodiment of the present invention. 2 shows a voltage detection circuit using the semiconductor device of FIG. 1, and FIG. 3 shows a VO1 terminal voltage waveform, a VCC terminal voltage waveform, a VO2 terminal voltage waveform, and an IPC current waveform of this voltage detection circuit.
[0018]
The semiconductor device in FIG. 1 includes a connection terminal VO1, a reference voltage terminal VCC, a voltage detection terminal VO2, a detection signal output terminal VPC for transmitting a detection signal, and a ground terminal GND. / SOURCE consists of a total of five terminals. There is a regulator 1 between VO1 and VCC, and the reference voltage VCC is always kept constant during operation. A start / stop circuit 2, a constant current source 3, and a constant current source 4 are connected to the VCC. A switch element 5 is connected between the constant current source 4 and VO2, and VO2 is connected to a detection terminal of a comparator 7 having a reference voltage source 6 (hereinafter, this reference voltage is referred to as VBG). The output terminal of the comparator 7 and the output terminal of the start / stop circuit 2 are both connected to the input terminal of the NAND circuit 8, and the output signal of the NAND circuit 8 is connected to the gate terminals of the switch elements 5 and 9. The constant current source 3 forms a current mirror circuit from the switch element 10 and the switch element 11, and the switch element 9 is connected between the constant current source 3 and the switch element 11. The switch element 10 is connected to the detection signal output terminal VPC.
[0019]
The voltage detection circuit shown in FIG. 2 includes a resistor 15 (resistance value) in which the VO1 of the semiconductor device 12 of FIG. 1 is connected to the VOUT terminal 13 from which the voltage is detected, and the VO2 terminal is connected in series between the VOUT terminal 13 and the GND / SOURCE terminal. Is connected to the connection point of the resistor 16 (the resistance value is R16). The VPC terminal is connected to a light emitting portion of a photocoupler 17 as detection signal output means, and a capacitor 18 is connected to VCC. Further, when the light emitting portion 17a of the photocoupler is not emitting light, power is supplied to the capacitor 14 connected to the VOUT terminal 13, and when the light emitting portion 17a of the photocoupler is emitting light, the power to the capacitor 14 is supplied. The power supply is stopped.
[0020]
The operation of the first semiconductor device of the present invention and the voltage detection circuit using the same will be described with reference to FIG.
[0021]
When power is supplied to the capacitor 14 connected to the VOUT terminal 13, the voltage across the capacitor 14 rises. Therefore, a current is supplied from VO1 of the voltage detection semiconductor device 12 connected to the VOUT terminal 13 to the capacitor 18 connected to VCC via the regulator 1, and the voltage of VCC also rises. When the VCC voltage becomes equal to or higher than the start voltage VCC0 set by the start / stop circuit 2, the voltage detecting semiconductor device 12 starts, and the output signal from the start / stop circuit 2 starts from the “L (low)” signal. “H” signal. As a result, the output signal of the NAND circuit 8 depends on the output signal of the comparator 7 and voltage detection at the VOUT terminal 13 is started. Here, the voltage of the VCC terminal is controlled so that a current is supplied from the VOUT terminal 13 to the capacitor 18 connected to the VCC terminal via the regulator 1, and is set to a constant voltage VCC 1 (> VCC 0) by the regulator 1. . The power supply to the voltage detecting semiconductor device 12 is supplied from the capacitor 18, and each component circuit is designed to reduce power consumption.
[0022]
When the voltage at the VOUT terminal 13 rises, that is, the VO2 terminal voltage rises and becomes equal to or higher than the reference voltage VBG of the comparator 7 (VBG = Vo · R16 / (R15 + R16) when the detection voltage at the VOUT terminal 13 is Vo). The output signal is changed from the “L (low)” signal to the “H (high)” signal. Since both the output signal of the start / stop circuit 2 and the output signal of the comparator 7 are “H (high)” signals, the output signal of the NAND circuit 8 is “L (low)”. As a result, the switch element 9 is turned on, so that a current flows from the constant current source 3 to the switch element 11 via the switch element 9. Thereby, the switch element 10 is also turned on. When the switch element 10 is turned on, a current flows through the light emitting element 17a of the photocoupler, the light emitting element 17a of the photocoupler emits light, an output signal is transmitted to the power supply source to the external capacitor 14, and the capacitor 14 The power supply to is stopped. At the same time, since the switch element 5 is also turned on by the output signal of the NAND circuit 8, I4 flows from the constant current source 4 to the resistor 16 connected to the VO2 terminal via the switch element 5, and the voltage at the VOUT terminal 13 is I4 · (R15 + R16) is raised, and the voltage at the VOUT terminal 13 becomes Vo + I4 · (R15 + R16). Since the power supply to the capacitor 14 is stopped by the transmission signal of the light emitting element 17a of the photocoupler, the voltage at the VOUT terminal 13 gradually decreases from Vo + I4 · (R15 + R16) (the VO2 terminal voltage also decreases).
[0023]
When the VO2 terminal voltage becomes equal to or lower than the reference voltage VBG of the comparator 7, the output signal of the comparator 7 becomes “L (low)”, and the output signal of the NAND circuit 8 becomes “H (high)”. Is turned off. Accordingly, since the switch element 10 is turned off, no current flows through the light emitting portion 17a of the photocoupler, and the output signal to the power supply source to the capacitor 14 is stopped, so that power is supplied to the capacitor 14 again. . As a result, the voltage of VOUT13 rises again (VO2 terminal voltage also rises).
[0024]
Thereafter, by repeating this operation, the voltage at the VOUT terminal 13 is controlled to be the desired voltage Vo.
[0025]
Here, as described above, the ripple voltage width of the VOUT terminal 13 is constant as I4 · (R15 + R16) regardless of the state of the load connected to the VOUT terminal 13.
[0026]
As described above, the following effects are obtained.
(1) A current IPC (= α · I3, where α represents a mirror ratio) flowing through the light emitting portion 17a of the photocoupler is constituted by the constant current source 3 of the voltage detecting semiconductor device 12 and the switch elements 10 and 11. Since adjustment can be performed with a current mirror circuit, the power consumption during detection can be reduced by narrowing down the IPC. As described above, since the circuit current of the voltage detecting semiconductor device 12 is reduced, the power consumed during the normal operation can be reduced. Specifically, the total current consumed by the voltage detecting semiconductor device 12, the resistors 15 and 16, and the photocoupler 17 can be reduced to about 1/10 or less of the conventional example.
(2) Since the ripple voltage at the VOUT terminal 13 is determined by I4 · (R15 + R16) and is constant regardless of the state of the load connected to the VOUT terminal 13, the ripple voltage can be adjusted by adjusting I4, R15, and R16. Can be made lower.
(3) The number of parts of the output voltage detection circuit is 6, and the number of parts is reduced.
[0027]
FIG. 4 shows a semiconductor device representing the second embodiment of the present invention. 5 shows a voltage detection circuit using the semiconductor device of FIG. 4, and FIG. 6 shows a VO1 terminal voltage waveform, a VCC terminal voltage waveform, a VO2 terminal voltage waveform, and an IPC current waveform of this voltage detection circuit.
[0028]
The semiconductor device shown in FIG. 4 has a constant current source 19 added to FIG. 1, so that a constant current α · I3 flows when the voltage at the VOUT terminal 13 is equal to or lower than the desired voltage Vo (however, The other configurations, operations, and characteristics are the same as those in FIG. 1 except that the light emitting unit 17a of the photocoupler does not emit light due to current. Since the constant current source 19 is connected, the gate voltages of the switch element 10 and the switch element 11 are always fixed to the “H (high)” state while the voltage detection semiconductor device 12 is detecting the voltage at the VOUT terminal 13. Therefore, the operation as a semiconductor device is ensured.
[0029]
FIG. 7 shows a switching power supply device using a transformer, which is a first power supply device of the present invention using the voltage detection circuit of FIG. The input voltage power supply 21 is rectified by the rectifier circuit 23 via the filter circuit 22 and smoothed by the input side smoothing capacitor 24. The voltage smoothed by the input side smoothing capacitor 24 is connected to the primary side winding 20a of the transformer 20, and energy is transmitted to the secondary side winding 20b of the transformer by switching of the switching element 27 by the control circuit 26. Here, as indicated by 28 in FIG. 7, if the control circuit 26 and the switching element 27 are integrated on the same substrate, there is an advantage that the number of parts can be reduced and the cost can be reduced.
[0030]
The energy transmitted to the secondary winding 20b is supplied to the output side smoothing capacitor. The voltage across the output-side smoothing capacitor 14 is divided by the resistors 15 and 16 and controlled to a desired voltage by the voltage detecting semiconductor device 12. The contents of the control operation are the same as those in FIG. 3, and the power supply is characterized in that a highly accurate output voltage with low power consumption and low ripple voltage can be obtained. When an output signal is transmitted from the light emitting unit 17a of the photocoupler to the light receiving unit 17b of the photocoupler, the light receiving unit 17b is turned on, and the on / off control of the switching element 27 by the control circuit 26 is stopped. Here, even when the voltage detection circuit shown in FIG. 5 is used, the operation is the same.
[0031]
FIG. 8 shows a step-down chopper switching power supply using a coil, which is a second power supply of the present invention using the voltage detection circuit of FIG. When the input voltage power source 21 is input from the VIN terminal in FIG. 8 and rectified by the rectifier circuit 30 formed of a diode, the input side smoothing capacitor 24 smoothes the input voltage. The voltage smoothed by the input-side smoothing capacitor 24 is switched from the coil 32 to the output-side smoothing capacitor 14 when the switching element 27 is turned on, and regenerated when the switching element 27 is turned off. Electric power is supplied from the diode 31 to the output-side smoothing capacitor 14 via the coil 32. Here, as indicated by 28 in FIG. 8, as in the case of FIG. 7, if the control circuit 26 and the switching element 27 are integrated on the same substrate, there is an advantage that the number of parts can be reduced and the cost can be reduced. .
[0032]
The voltage across the output-side smoothing capacitor 14 is divided by the resistors 15 and 16 and controlled to a desired voltage by the voltage detecting semiconductor device 12. The contents of the control operation are the same as those in FIG. 3, and the power supply is characterized in that a highly accurate output voltage with low power consumption and low ripple voltage can be obtained. When an output signal is transmitted from the light emitting unit 17a of the photocoupler to the light receiving unit 17b of the photocoupler, the light receiving unit 17b is turned on, and the on / off control of the switching element 27 by the control circuit 26 is stopped. Thereby, the power supply to the output side smoothing capacitor 14 is stopped. Here, even when the voltage detection circuit shown in FIG. 5 is used, the operation is the same.
[0033]
FIG. 9 shows a step-down chopper switching power supply using a coil, which is a third power supply of the present invention using the voltage detection circuit of FIG. In the step-down chopper switching power supply shown in FIG. 8, the photocoupler 17 is used as the voltage detection signal transmission means. In FIG. 9, however, the on / off control of the switching element 27 by the control circuit 26 is stopped. The VPC terminal of the voltage detection semiconductor device 12 is directly connected to the FB terminal of the switch circuit 10 and the switch element 10 is turned on when the desired voltage Vo of the VOUT terminal 13 is detected. Stop on / off control. Here, when the input voltage VIN is a high voltage, the switch element 10 needs to use a high breakdown voltage element. The contents of the control operation are the same as those in FIG. 8, and the power supply is characterized by low power consumption and high output voltage with low ripple voltage.
[0034]
In the step-down chopper switching power supply device of FIG. 9, even when the voltage detection circuit shown in FIG. 5 is used, the control operation is the same as in FIG. 8, and the power supply has low power consumption and low ripple voltage accuracy. There is a feature that a high output voltage can be obtained. Here, in order to stop the on / off control of the switching element 27 by the control circuit 26, the magnitude relationship between the current value IFB flowing from the FB terminal and α · I3 in FIG. 6 is IFB> α · I3.
[0035]
【The invention's effect】
According to the present invention, low power consumption can be measured in the voltage detection circuit. In particular, in a power supply device using the voltage detection semiconductor device of the present invention, the efficiency of the power supply can be increased.
[0036]
Further, since the ripple voltage can be controlled to be constant at all times and the ripple voltage can be suppressed, high-precision control as a power source is possible.
[0037]
Further, since the number of components constituting the voltage detection circuit can be reduced, it is possible to reduce the size and cost.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram inside a voltage detection semiconductor device according to a first embodiment of the present invention. FIG. 2 is a circuit configuration diagram of a voltage detection circuit according to a first embodiment of the present invention. FIG. 4 is a diagram for explaining the circuit operation of the voltage detection circuit according to the first embodiment. FIG. 4 is a circuit configuration diagram inside the voltage detection semiconductor device according to the second embodiment of the present invention. 6 is a circuit configuration diagram of a voltage detection circuit according to the second embodiment. FIG. 6 is a diagram for explaining a circuit operation of the voltage detection circuit according to the second embodiment. FIG. 7 is according to the third embodiment of the invention. FIG. 8 is a circuit configuration diagram of a power supply device according to a fourth embodiment of the present invention. FIG. 9 is a circuit configuration diagram of a power supply device according to a fifth embodiment of the present invention. FIG. 11 is a circuit configuration diagram showing a conventional voltage detection circuit. FIG. 11 is a circuit diagram for explaining the circuit operation of the conventional voltage detection circuit. [Figure 12] of the entire power supply device using a conventional voltage detecting circuit diagram EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 1 Regulator 2 Start / stop circuit 3 Constant current source 4 Constant current source 5 Switch element 6 Reference voltage source 7 Comparator 8 NAND circuit 9 Switch element 10 Switch element 11 Switch element 12 Voltage detection semiconductor device 13 Output voltage terminal 14 Output side smoothing Capacitors 15 and 16 Resistance 17 Photocoupler 17a Photocoupler light emitting portion 17b Photocoupler light receiving portion 18 Capacitor 19 Constant current source 20 Transformer 20a Transformer primary winding 20b Transformer secondary winding 21 Input voltage source 22 Filter circuit 23 Rectifier circuit 24 Input-side smoothing capacitor 25 Snubber circuit 26 Control circuit 27 Switching element 28 Range integrated on the same semiconductor substrate 29 Capacitor 30 Rectifier circuit 31 Regenerative diode 32 Coil

Claims (5)

A regulator having one end connected to an output voltage terminal (Vout) for voltage detection , and the other end connected to a reference voltage terminal;
A first constant current source, a second constant current source, and a start / stop circuit connected to the reference voltage terminal;
A NAND circuit in which the other end of the start / stop circuit is connected to a first input terminal;
A current comprising the first constant current source, a first switch element, and a second switch element, and a detection signal output terminal for transmitting a detection signal to the output terminal of the first switch element is connected Mirror circuit,
A third switch element connected between the first constant current source of the current mirror circuit and the second switch element and having a control terminal to which an output terminal of the NAND circuit is connected;
A fourth switch element having one end connected to the second constant current source, the other end connected to a voltage detection terminal, and a control terminal connected to the output terminal of the NAND circuit;
A semiconductor device comprising: a comparator having the voltage detection terminal connected to a detection terminal, a reference voltage source connected to a reference terminal, and an output terminal connected to a second input terminal of the NAND circuit. A regulator having one end connected to an output voltage terminal (Vout) for voltage detection , and the other end connected to a reference voltage terminal;
A first constant current source, a second constant current source, a third constant current source, and a start / stop circuit connected to the reference voltage terminal;
A NAND circuit in which the other end of the start / stop circuit is connected to a first input terminal;
A current comprising the third constant current source, a first switch element and a second switch element, and a detection signal output terminal for transmitting a detection signal to the output terminal of the first switch element is connected Mirror circuit,
A third switch element connected between the first constant current source and the second switch element and having a control terminal to which an output terminal of the NAND circuit is connected;
A fourth switch element having one end connected to the second constant current source, the other end connected to a voltage detection terminal, and a control terminal connected to the output terminal of the NAND circuit;
A semiconductor device comprising: a comparator having the voltage detection terminal connected to a detection terminal, a reference voltage source connected to a reference terminal, and an output terminal connected to a second input terminal of the NAND circuit.   3. The semiconductor device according to claim 1, comprising at least five terminals: a ground terminal, a connection terminal, a reference voltage terminal, a voltage detection terminal, and a detection signal output terminal.   4. A first resistor connected between a connection terminal and a voltage detection terminal of the semiconductor device according to claim 1, and a second resistance connected between the voltage detection terminal and a ground terminal. A first capacitor connected between the reference voltage terminal and the ground terminal, a second capacitor connected between the connection terminal and the ground terminal, and a voltage detection signal transmitting means connected to the detection signal output terminal. 4. A voltage detection circuit using the semiconductor device according to claim 1, 2, or 3.   5. A power supply apparatus using the voltage detection circuit according to claim 4 for an output voltage detection unit.

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