Semiconductor equipment for power control, isolated power supply unit, and drive semiconductor equipment.

Abstract

This invention provides a semiconductor device for power control that allows for miniaturization and cost reduction of equipment while increasing the degree of freedom for users in optimizing the design. [Solution] An isolated power supply device comprising a drive circuit unit that generates on / off drive signals for a switching element connected to the primary winding of a transformer, and a control circuit unit that generates on / off control signals for the switching element and supplies them to the drive circuit unit, wherein the drive circuit unit and the control circuit unit are each formed as semiconductor integrated circuits on separate semiconductor chips, and the device is configured such that the first semiconductor chip on which the control circuit unit is formed and the second semiconductor chip on which the drive circuit unit is formed are enclosed in a single package. Furthermore, the control circuit unit generates an operation control signal to stop the operation of the drive circuit unit and outputs it to the drive circuit unit, and the drive circuit unit is configured to stop its operation based on the input operation control signal.

Description

Technical Field

[0001] The present invention relates to a semiconductor device for power supply control that controls a switching element connected in series with a primary winding of a transformer for voltage conversion, an isolated power supply device using the same, and a semiconductor device for driving.

Background Art

[0002] Conventionally, as one of switching power supply devices, a transistor (including transistors on GaN and SiC substrates in addition to silicon substrates) as a switching element for intermittently flowing current through a primary winding of a transformer and a control circuit (IC) for controlling on and off of the switching element are provided. By flowing current through the primary winding, the current induced in the secondary winding is rectified by a diode and smoothed by a capacitor for output, which is a switching power supply device (isolated DC-DC converter).

[0003] In addition, in a DC power supply device, there is an isolated AC-DC converter (AC adapter) that includes a diode bridge circuit for rectifying an AC power supply and降压 the rectified DC voltage by the above switching power supply device (isolated DC-DC converter) to convert it into a DC voltage of a desired potential. As a control IC (semiconductor device for power supply control) on the primary side of the AC adapter, an IC of a PWM control / quasi-resonant control method is known.

[0004] By the way, regarding recent power supply devices, especially AC adapters, there is a demand for high output and high power density for miniaturization. To achieve miniaturization, a method of increasing the switching frequency to reduce the size of the transformer is effective. However, when the switching frequency is increased in a semiconductor device for power supply control of the PWM control / quasi-resonant control method, the power loss increases and the efficiency decreases. Furthermore, to improve efficiency, some power supply control semiconductor devices employ a zero-voltage switching (ZVS) control method, which involves providing an active clamp circuit with an energy regeneration function on the primary winding side of the transformer and performing switching at the timing when the voltage is zero. Inventions relating to switching power supply devices equipped with an active clamp circuit are described, for example, in Patent Documents 1 to 3. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-8846 [Patent Document 2] Japanese Patent Publication No. 2023-92557 [Patent Document 3] Japanese Patent Publication No. 2023-92559 [Overview of the project] [Problems that the invention aims to solve]

[0006] In isolated AC-DC converters equipped with an active clamp circuit and employing a ZVS control method, prioritizing miniaturization by reducing the number of devices constituting the primary side circuit—for example, by integrating the switching transistors in series with the primary side winding or the switching transistors constituting the active clamp circuit into the driver IC—presents a challenge: it reduces the user's freedom in optimizing the design. On the other hand, prioritizing increased user design freedom leads to an increase in the number of components, resulting in larger equipment and higher costs.

[0007] This invention was made in view of the above-mentioned problems, and its objective is to enable users to miniaturize and reduce the cost of isolated power supply devices equipped with active clamp circuits and power control semiconductor devices that constitute them, while increasing the degree of freedom for optimization design. Another object of the present invention is to provide a power control semiconductor device and a drive semiconductor device that can achieve low power consumption during standby. [Means for solving the problem]

[0008] To achieve the above objective, the present invention In an isolated power supply device comprising a transformer for voltage conversion, a first switching element connected in series with the primary winding of the transformer, an active clamp circuit connected between the terminals of the primary winding of the transformer, and a power supply control semiconductor device that controls the first switching element and the second switching element constituting the active clamp circuit, A current-voltage conversion element is connected in series with the first switching element. The aforementioned power control semiconductor device is A drive circuit unit that generates an on / off drive signal for the first switching element and an on / off drive signal for the second switching element, A first external terminal that outputs an on / off drive signal for the first switching element generated by the drive circuit section, A second external terminal that outputs an on / off drive signal for the second switching element generated by the drive circuit section, A third external terminal to which the voltage converted by the current-voltage conversion element is input, A fourth external terminal to which a feedback signal from the secondary side of the transformer is input, The system comprises a control circuit unit that generates and supplies on / off control signals for the first switching element and the second switching element to the drive circuit unit, The drive circuit section and the control circuit section are each formed as semiconductor integrated circuits on separate semiconductor chips. The device is configured such that the first semiconductor chip on which the control circuit section is formed and the second semiconductor chip on which the drive circuit section is formed are enclosed in a single package. The aforementioned control circuit unit is A control signal is generated to turn off the first switching element based on the voltages of the third external terminal and the fourth external terminal. An operation control signal is generated to control the operation of the drive circuit based on the on / off control signal of the first switching element and the on / off control signal of the second switching element, and this signal is output to the drive circuit. The drive circuit section is configured to be able to stop the operation of some circuits based on the input operation control signal.

[0009] With the above configuration, the control chip and driver chip are enclosed in a single package, thus reducing the number of components and the mounting area on the circuit board. This allows for miniaturization of the device and reduction of costs. The single-package device can be either a leadless device (leadless package) or a device with leads. Furthermore, since the switching transistors in series with the primary winding and the switching transistors constituting the active clamp circuit are external components of the aforementioned single-package device, the user can optimize the system by selecting the optimal elements to realize a power supply system with the desired characteristics, thereby increasing the degree of freedom in optimized design. Furthermore, since the drive circuit is configured to stop the operation of some circuits based on the input operation control signal, low power consumption can be achieved during standby. [Effects of the Invention]

[0010] According to the present invention, an isolated power supply device equipped with an active clamp circuit can be miniaturized and its cost reduced. Furthermore, it allows users greater freedom in optimizing the design. Additionally, it has the effect of achieving low power consumption during standby. [Brief explanation of the drawing]

[0011] [Figure 1]This is a circuit configuration diagram showing an embodiment of an AC-DC converter to which an isolated power supply device according to the present invention is applied. [Figure 2] This is a circuit configuration diagram showing a configuration example of a semiconductor device for power control that constitutes the AC-DC converter of FIG. 1. [Figure 3] This is a circuit configuration diagram showing an example of a driver chip that constitutes the semiconductor device for power control of FIG. 2.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit configuration diagram showing an embodiment of an AC-DC converter to which an isolated power supply device according to the present invention is applied. The AC-DC converter 10 of this embodiment is a flyback converter, and includes an AC power line filter circuit (AC filter) 12 for noise removal, which is composed of an X capacitor C0 and a common mode choke coil L1 connected between a pair of AC terminals to which an AC voltage (AC) from an AC power supply 11 is input, a diode bridge circuit 13 for rectifying the AC voltage from the AC power supply 11, a smoothing capacitor C1, and a transformer 14 for voltage conversion having a primary winding Np, a secondary winding Ns, and an auxiliary winding Nb.

[0013] Further, the AC-DC converter 10 of this embodiment includes a switching transistor SW1 connected in series with the primary winding Np of the transformer 14, and a semiconductor device for power control (hereinafter referred to as a power control device) 15 that drives the switching transistor SW1 on and off. Furthermore, the AC-DC converter 10 of the present embodiment includes an active clamp circuit 16 having a switching transistor SW2 and a capacitor C2 in parallel connection, which are connected between the low-side terminal of the primary winding Np of the transformer 14 and the diode bridge circuit 13. The power control device 15 is provided with an active clamp control function for controlling the transistor SW2 of the active clamp circuit 16. Also, a discharge resistor R2 for discharging the charge of the capacitor C2 is connected in parallel with the capacitor C2.

[0014] In addition, the AC-DC converter 10 of the present embodiment uses a transformer having an auxiliary winding Nb with a center tap as the transformer 14. A rectifying and smoothing circuit 17A, in which a rectifying diode D11, a resistor R11, and a smoothing capacitor C11 are connected in series, is provided between the high-side terminal of the auxiliary winding Nb and the ground point. The voltage rectified and smoothed by the rectifying and smoothing circuit 17A is applied to the auxiliary power terminal AUXR of the power control device 15. By using a transformer in which a voltage, for example, four times the secondary-side output voltage is induced in the auxiliary winding Nb, when the secondary-side output voltage has a fluctuation range of 3V to 20V, a voltage of 12V to 80V can be input to the auxiliary power terminal AUXR.

[0015] Furthermore, a rectifying and smoothing circuit 17B, in which a rectifying diode D12, a resistor R12, and a smoothing capacitor C12 are connected in series, is provided between the center tap of the auxiliary winding Nb and the ground point. The voltage rectified and smoothed by the rectifying and smoothing circuit 17B is applied to the external power terminal VDD of the power control device 15. Further, the power control device 15 is provided with an external terminal VBUS to which a voltage obtained by dividing the voltage between the terminals of the auxiliary winding Nb with resistors R4 and R5 is input, and a high-voltage input start terminal HV to which the voltage from the AC power supply 11 at the time of power-on is input as a starting voltage through diodes D1, D2, and a resistor R1.

[0016] In this embodiment, the switching transistor SW1 and the active clamping transistor SW2, which are connected in series with the primary winding Np, are configured as discrete components using N-channel MOSFETs (insulated-gate field-effect transistors). Furthermore, to reduce losses due to drive current, it is desirable to use GaN transistors with small gate charge amounts for SW1 and SW2. Furthermore, the power control device 15 is provided with an external output terminal LGATE that outputs a signal to drive the gate terminal of transistor SW1, an external output terminal HGATE that outputs a signal to drive the gate terminal of transistor SW2, and a current detection terminal CS which is an external terminal to which a voltage converted from current by a sense resistor R3 that detects the drain current of transistor SW1 is input. Furthermore, the power control device 15 is provided with an external terminal FB to which a phototransistor PT is connected, which receives a light feedback signal from the secondary side of the transformer 14.

[0017] On the other hand, the secondary side of the transformer 14 includes a synchronous rectifier MOS transistor TR1 connected in series with the secondary winding Ns, a secondary side control IC 20 that uses the voltage generated on the secondary side as the power supply voltage, detects the source and drain voltages of the synchronous rectifier MOS transistor TR1 and generates on / off control signals for the transistor TR1, and a smoothing capacitor C3 connected between the output terminals to stabilize the output voltage.

[0018] Furthermore, although not particularly limited, the AC-DC converter of this embodiment is configured to be applicable to a system to which a USB (Universal Serial Bus) standard power supply device 30 is connected as a load circuit. The power supply device 30 comprises a plug 31 having four terminals VBUS, PSUB, CC1, and CC2 as defined by the USB standard, a USB-PD (Power Delivery) compliant controller 32 connected to terminals PSUB, CC1, and CC2 of the plug 31, and a transistor TR2 connected between the secondary winding Ns and terminal VBUS. Transistor TR2 is controlled according to information received by the controller 32 via terminals CC1 and CC2 of the plug 31, and outputs a voltage compliant with the USB-PD standard to the VBUS terminal.

[0019] Furthermore, a feedback photodiode PD is connected between the VBUS terminal of the secondary winding Ns and the USB-PD controller 32, and the controller 32 is configured to supply a current to the photodiode PD that corresponds to the level of the secondary output voltage. Specifically, the USB-PD controller 32 incorporates a shunt regulator to which a voltage obtained by dividing the secondary output voltage is applied, and the shunt regulator is configured to supply a current to the photodiode PD that is proportional to the level of the secondary output voltage. The photodiode PD and the primary-side phototransistor PT constitute a photocoupler as an isolated signal transmission means. Light emitted from the secondary-side photodiode PD is received by the primary-side phototransistor PT, generating a feedback signal corresponding to the light intensity, which is input to the external terminal FB. The primary-side power control device 15 generates a signal to turn off the switching transistor SW1, which is connected in series with the primary-side winding Np, according to this feedback signal and the voltage of the external terminal (current detection terminal) CS.

[0020] The AC-DC converter 10 of this embodiment is characterized in that, as a power control device 15, it is configured as a one-package device in which an IC chip (driver chip) that incorporates a driver for driving the gate terminals of the switching transistors SW1 and SW2, and an IC chip (control chip) that generates a control signal to be input to the driver chip are mounted on a thin plate made of, for example, a CU alloy material and enclosed in a single package, and an enable signal EN that controls the operating state of the driver is supplied from the control chip to the driver chip. The one-package device 15 may be configured as a leadless device (leadless package) or as a device with leads.

[0021] Figure 2 shows an embodiment of the power control device 15 having the features described above. As shown in Figure 2, the power control device 15 of this embodiment includes a control chip 51 and a driver chip 52. Of these, the control chip 51 includes an internal regulator 511 that generates the internal power supply voltage Vdd of the device using the voltage of the external power supply terminal AUXR of the device 15, and an internal circuit 512 that generates a signal ON / OFF1 indicating the on / off timing of the switching transistor SW1 and a signal ON / OFF2 indicating the on / off timing of the transistor SW2 of the active clamp circuit 16, and outputs them to the driver chip 52. This internal circuit 512 operates using the internal power supply voltage Vdd generated by the internal regulator 511 or the voltage from the rectifier smoothing circuit 17B.

[0022] The built-in regulator 511 within the control chip 51 is a linear regulator. By using a linear regulator, the generation of noise associated with the internal power supply voltage can be suppressed. In addition, a capacitor C13 is connected to the VDD terminal to raise the external power supply terminal VDD to the operating start voltage (switching start) by flowing current from the HV terminal when the power is turned on. Furthermore, in the voltage control device 15 of this embodiment, although not particularly limited, the internal circuit 512 is configured to have a function of performing ZVS (zero voltage switching) control, which turns on SW1 based on the drain voltage of the switching transistor SW1 (voltage of the external terminal HGND).

[0023] Furthermore, the internal circuit 512 monitors, for example, the ON / OFF1 and ON / OFF2 on / off timing signals of switching transistors SW1 and SW2 that the internal circuit 512 outputs to the driver chip 52. When it determines that the output voltage on the secondary side has dropped and that both SW1 and SW2 are not switching, the internal circuit 512 determines that there is no need to operate the driver, and therefore negates the enable signal EN output to the driver chip 52, transitioning to a standby state and stopping the operation of some circuits within the driver chip 52. The state in which switching transistors SW1 and SW2 cease to switch occurs when the output power decreases and the feedback signal from the secondary side (voltage at the FB terminal) drops, causing the on / off timing signals ON / OFF1 and ON / OFF2 of SW1 and SW2 to stop changing. Therefore, the internal circuit 512 may monitor the voltage at the FB terminal to determine the standby state and negate the enable signal EN. In this embodiment, the standby state is the period during burst mode operation in which the signals ON / OFF1 and ON / OFF2 do not change.

[0024] Meanwhile, the driver chip 52 includes a MOS transistor M1 for raising the gate voltage of switching transistor SW2 to a high level, a MOS transistor M2 for lowering the gate voltage of SW2 to a low level, a MOS transistor M3 for raising the gate voltage of switching transistor SW1 to a high level, and a MOS transistor M4 for lowering the gate voltage of SW1 to a low level. Furthermore, the driver chip 52 includes an internal circuit 52A that generates control signals for transistors M1 and M2 based on an ON / OFF timing signal ON / OFF2 input from the control chip 51, and an internal circuit 52B that generates control signals for transistors M3 and M4 based on an ON / OFF timing signal ON / OFF1 input from the control chip 51.

[0025] In the power control device 15 of this embodiment, the totem-pole output stage consisting of the internal circuit 52B on the low side of the driver chip 52 and M3, M4 is operated by the internal power supply voltage Vdd generated by the built-in regulator 511 or the voltage generated by the rectifier-smoothing circuit 17B and applied to the external power supply terminal VDD. Furthermore, the built-in regulator 511 outputs the input voltage as is when the voltage Vrsa supplied from the rectifier-smoothing circuit 17A is lower than the set output voltage, and when the voltage Vrsa is higher than the set output voltage, it steps down the input voltage Vrsa to the set output voltage and outputs it.

[0026] On the other hand, the totem-pole output stage of the driver chip 52, consisting of internal circuit 52A and M1, M2, is configured to operate using a voltage boosted by an external diode D14 and capacitor C14 and supplied to the external power supply terminal HVDD as the power supply voltage. This allows the switching transistor SW2 to be turned on by applying a voltage higher than the source voltage of SW2 to the gate terminal of SW2. Furthermore, the anode terminal of diode D14 is connected to the output node of the rectifier-smoothing circuit 17B, and the cathode terminal is connected to the connection node N1 (the drain terminal of SW1) between SW2 and SW1 via capacitor C14. Node N1 is connected to the external terminal HGND of the power control device 15. Therefore, when SW1 is turned on, charge is accumulated in capacitor C14 via diode D14, and when SW1 is turned off, the charge accumulated in capacitor C14 pushes up the potential of the HVDD terminal, driving SW2. In other words, a voltage based on the potential of the HGND terminal is applied to the HVDD terminal.

[0027] Figure 3 shows a specific embodiment of the driver chip 52, particularly the internal circuits 52A and 52B, that constitute the power control device 15. As shown in Figure 3, the driver chip 52 in this embodiment is provided with control input terminals HIN and LIN, and a control terminal EN to which the enable signal supplied from the control chip 51 is input. The ON / OFF timing signal ON / OFF2 of the switching transistor SW2 supplied from the control chip 51 is input to control input terminal HIN, and the ON / OFF timing signal ON / OFF1 of the switching transistor SW1 is input to control input terminal LIN. Pull-down resistors R21 and R22 are connected to the control signal input terminals HIN and LIN, respectively.

[0028] The internal circuit 52A includes a Schmitt trigger circuit 521A connected to the control signal input terminal HIN, and a pulse generation circuit 522 that generates a pulse signal based on the output signal of the Schmitt trigger circuit 521A. The pulse generation circuit 522 detects the rising and falling edges of the ON / OFF timing signal ON / OFF2 of SW2 and generates pulse signals accordingly.

[0029] Furthermore, the internal circuit 52A includes a level shift circuit 523 that converts the pulse signal from the pulse generation circuit 522 into a pulse signal that can handle high voltage, an RS flip-flop 526 that performs set / reset operations based on the pulse signal level-shifted by the level shift circuit 523, and a driver circuit 527A that receives the output signal Q of the flip-flop 526 and generates drive signals for the totem pole output stages (M1, M2). The level shift circuit 523 is composed of two common-source circuits consisting of MOS transistors M5, M6 to which the pulse signal generated by the pulse generation circuit 522 is applied to the gate terminal, and drain resistors Rd1, Rd2. Furthermore, the level shift circuit 523, RS flip-flop 526, and driver circuit 527A are configured to operate using the voltage of the external terminal HGND as the reference potential and the voltage of the external power supply terminal HVDD as the power supply voltage, with HGND and HVDD lines provided within the chip.

[0030] Furthermore, although not limited thereto, a filter circuit 524 is provided between the level shift circuit 523 and the RS flip-flop 526 to block high-frequency noise, and a low-voltage malfunction prevention circuit (UVLO) 525A is provided that resets the RS flip-flop 526 and stops the operation of the driver circuit 527A when the voltage of the external power supply terminal HVDD drops below a predetermined level.

[0031] Furthermore, in this embodiment, the pulse generation circuit 522 is input to a signal output by the low-voltage malfunction prevention circuit 525B on the internal circuit 52B side when the voltage at the external power supply terminal VDD drops below a predetermined level. The pulse generation circuit 522 is configured to stop operating when the VDD voltage drops. When the pulse generation circuit 522 stops operating, the source-grounded MOS transistors M5 and M6 that constitute the level shift circuit 523 are turned off, and no current flows to the level shift circuit 523.

[0032] On the other hand, the internal circuit 52B includes a Schmitt trigger circuit 521B with an input terminal connected to the control input terminal LIN, a delay circuit 528 that delays the output signal of the Schmitt trigger circuit 521B, and a driver circuit 527B that receives the delayed signal from the delay circuit 528 and generates drive signals for the totem pole output stages (M3, M4). The driver circuit 527B is configured such that the voltage of the ground terminal GND is used as the reference potential and the voltage of the external power supply terminal VDD is used as the power supply voltage, with the internal power supply lines and ground lines of the IC arranged accordingly. Furthermore, the internal circuit 52B includes a regulator (HYSREG) 529 that generates the operating voltage of the Schmitt trigger circuit 521B based on the voltage of the external power supply terminal VDD, and an undervoltage malfunction prevention circuit (UVLO) 525B that stops the operation of the driver circuit 527B when the voltage of the external power supply terminal VDD drops below a predetermined level.

[0033] In the internal circuit 52B, the operation of the regulator 529 can be stopped by an enable signal (EN) input from the control chip 51 to the control terminal EN. The enable signal (EN) is also input to the undervoltage malfunction prevention circuit 525B, and when the enable signal (EN) is negated, the undervoltage malfunction prevention circuit 525B stops the operation of the driver circuit 527B.

[0034] Furthermore, the output signal of the low-side low-voltage malfunction prevention circuit 525B is supplied to the pulse generation circuit 522 of the internal circuit 52A, and when the operation of the driver circuit 527B stops, the operation of the pulse generation circuit 522 stops, and indirectly the operation of the driver circuit 527A also stops. In the circuit of the embodiment shown in Figure 3, the filter circuit 524, RS flip-flop 526, and driver circuit 527A do not completely stop operating due to the enable signal (EN), but it is also possible to configure them to completely stop operating.

[0035] Furthermore, the voltage generated by the regulator 529 of the internal circuit 52B on the low side is supplied as the operating voltage to the Schmitt trigger circuit 521A of the internal circuit 52A. When the operation of the regulator 529 is stopped by the enable signal (EN), the operation of the Schmitt trigger circuit 521A of the internal circuit 52A is also stopped. With the above configuration, the current consumption of the driver chip 52 can be reduced, thereby reducing power consumption during standby. Furthermore, the elements constituting the low-side circuit of the internal circuit 52A, the Schmitt trigger circuit 521A, and the elements (MOS transistors) constituting the pulse generation circuit 522 operate with reference to the potential of the GND terminal, while the filter circuit 524, UVLO 525A, RS flip-flop 526, and driver circuit 527A are configured to operate with reference to the potential of the HGND terminal.

[0036] As described above, in the AC-DC converter (isolated power supply) of this embodiment, the control chip 51 and the driver chip 52 are enclosed in a single package, forming a one-package device. Therefore, if a high-voltage switch element for ZVS or a starting switch element is required, these elements can be incorporated into the same package, which has the advantage of reducing the number of components and the mounting area on the circuit board. Furthermore, since the induced voltage of the auxiliary winding, which becomes high voltage, is input and stepped down to the internal power supply voltage Vdd by the built-in regulator 511, an external circuit is not required, further reducing the number of components.

[0037] Furthermore, in this embodiment, the switching transistor SW1 in series with the primary winding Np and the switching transistor SW2 constituting the active clamp circuit are external components of the package device (15). Therefore, the user can optimize the system by selecting the elements best suited to realizing a power supply system with desired characteristics. In other words, there is an advantage in that the user's freedom in optimizing the design is increased. Furthermore, since the driver chip 52's circuitry can be stopped by a control signal (enable signal EN) from the control chip 51, there is an advantage in that current consumption can be reduced and power consumption during standby can be decreased.

[0038] Although the present inventors' inventions have been described in detail based on embodiments, the present invention is not limited to the above embodiments. For example, in the above embodiments, a control chip and a driver chip were enclosed in a single package to form a package device, but the technique of sending an enable signal from the control unit to the driver unit to stop the operation of the driver unit in standby mode can also be applied to a primary-side power control IC that constitutes an isolated power supply device in which the control unit and the driver unit are formed as a semiconductor integrated circuit on a single semiconductor chip, thereby reducing the power consumption of the power control IC during standby.

[0039] Furthermore, in the above embodiment, a transformer 14 equipped with an auxiliary winding having a center tap is used, but it is also possible to use a configuration in which a transformer equipped with an auxiliary winding without a center tap is used. Furthermore, although the above embodiment described the case in which the present invention is applied to an AC-DC converter, the present invention can also be applied to a DC-DC converter in which the diode bridge circuit 13 is omitted. [Explanation of Symbols]

[0040] 11…AC power supply, 12…AC power filter, 13…Diode bridge circuit, 14…Transformer, 15…Power supply semiconductor device (power control device), 16…Active clamp circuit, 17A,17B…Rectifier smoothing circuit, 51…Control chip, 52…Driver chip, 521A,521B…Schmitt trigger circuit, 523…Level shift circuit, 525A,525B…Undervoltage lockout (UVLO) circuit, 527A,527B…Driver circuit

Claims

1. An isolated power supply device comprising: a transformer for voltage conversion; a first switching element connected in series with the primary winding of the transformer; an active clamp circuit connected between the terminals of the primary winding of the transformer; and a power supply control semiconductor device that controls the first switching element and the second switching element constituting the active clamp circuit, A current-to-voltage conversion element is connected in series with the first switching element. The aforementioned power control semiconductor device is A drive circuit unit that generates an on / off drive signal for the first switching element and an on / off drive signal for the second switching element, A first external terminal that outputs an on / off drive signal for the first switching element generated by the drive circuit section, A second external terminal that outputs an on / off drive signal for the second switching element generated by the drive circuit section, A third external terminal to which the voltage converted by the current-voltage conversion element is input, A fourth external terminal to which a feedback signal from the secondary side of the transformer is input, The system comprises a control circuit unit that generates and supplies on / off control signals for the first switching element and the second switching element to the drive circuit unit, The drive circuit section and the control circuit section are each formed as semiconductor integrated circuits on separate semiconductor chips. The device is configured such that the first semiconductor chip on which the control circuit section is formed and the second semiconductor chip on which the drive circuit section is formed are enclosed in a single package. The aforementioned control circuit unit is A control signal is generated to turn off the first switching element based on the voltages of the third external terminal and the fourth external terminal. An operation control signal is generated to control the operation of the drive circuit based on the on / off control signal of the first switching element and the on / off control signal of the second switching element, and this signal is output to the drive circuit. The drive circuit section is configured to stop the operation of some circuits based on the input operation control signal, making it an isolated power supply device.

2. The transformer is equipped with an auxiliary winding, The power control semiconductor device includes a fifth external terminal to which a voltage obtained by rectifying and smoothing the voltage induced in the auxiliary winding is input. The drive circuit section comprises a linear regulator that generates an internal power supply voltage based on the voltage of the fifth external terminal, a first signal receiving circuit that receives an on / off control signal for the first switching element, and a second signal receiving circuit that receives an on / off control signal for the second switching element. The first signal receiving circuit and the second signal receiving circuit are configured to operate on the internal power supply voltage generated by the linear regulator. The isolated power supply device according to claim 1, characterized in that the drive circuit is configured to stop generating the internal power supply voltage by the linear regulator when the operation control signal input from the control circuit instructs the operation to stop.

3. A boosting means for boosting the voltage of the fifth external terminal and a sixth external terminal to which the voltage boosted by the boosting means is input, The drive circuit section comprises a first drive circuit that generates a drive signal for the first switching element based on a signal received by the first signal receiving circuit, and a second drive circuit that generates a drive signal for the second switching element based on a signal received by the second signal receiving circuit. The isolated power supply device according to claim 2, characterized in that the first drive circuit operates using the voltage of the fifth external terminal as the power supply voltage, and the second drive circuit operates using the voltage of the sixth external terminal as the power supply voltage.

4. A power supply control semiconductor device comprising an isolated power supply device comprising a transformer for voltage conversion, a first switching element connected in series with the primary winding of the transformer, and an active clamp circuit connected between the terminals of the primary winding of the transformer, and having a function to control the first switching element and the second switching element constituting the active clamp circuit, A drive circuit unit that generates an on / off drive signal for the first switching element and an on / off drive signal for the second switching element, A first external terminal that outputs an on / off drive signal for the first switching element generated by the drive circuit section, A second external terminal that outputs an on / off drive signal for the second switching element generated by the drive circuit section, A third external terminal to which the voltage converted by a current-to-voltage conversion element connected in series with the first switching element is input, A fourth external terminal to which a feedback signal from the secondary side of the transformer is input, The system comprises a control circuit unit that generates and supplies on / off control signals for the first switching element and the second switching element to the drive circuit unit, The drive circuit section and the control circuit section are formed as semiconductor integrated circuits on a single semiconductor chip. The aforementioned control circuit unit is A control signal is generated to turn off the first switching element based on the voltages of the third external terminal and the fourth external terminal. An operation control signal is generated to control the operation of the drive circuit based on the on / off control signal of the first switching element and the on / off control signal of the second switching element, and this signal is output to the drive circuit. The power control semiconductor device is characterized in that the drive circuit section is configured to stop the operation of some circuits based on the input operation control signal.

5. A drive semiconductor device comprising an isolated power supply device comprising a transformer for voltage conversion, a first switching element connected in series with the primary winding of the transformer, and an active clamp circuit connected between the terminals of the primary winding of the transformer, and having the function of generating and outputting signals to drive the first switching element and the second switching element constituting the active clamp circuit on and off, A first signal receiving circuit that receives an on / off control signal for the first switching element and a second signal receiving circuit that receives an on / off control signal for the second switching element, A first drive circuit unit generates and outputs a signal to turn the first switching element on or off based on a control signal received by the first signal receiving circuit, A second drive circuit unit generates and outputs a signal to turn the second switching element on or off based on the control signal received by the second signal receiving circuit, An external control terminal to which a predetermined operation control signal is input, A drive semiconductor device comprising the above, characterized in that it is configured to stop the operation of the first drive circuit and the second drive circuit when the operation control signal input to the external control terminal instructs the operation to stop.

6. An external power terminal that receives voltage supplied from an external source, A linear regulator that generates an internal power supply voltage based on the voltage of the external power supply terminal, The system comprises a first signal receiving circuit that receives an on / off control signal for the first switching element and a second signal receiving circuit that receives an on / off control signal for the second switching element. The first signal receiving circuit and the second signal receiving circuit are configured to operate on the internal power supply voltage generated by the linear regulator. The drive semiconductor device according to claim 5, characterized in that it is configured to stop generating the internal power supply voltage by the linear regulator when the operation control signal input to the external control terminal instructs the operation to stop.

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