JP5173762B2 - Switching power supply - Google Patents

Description

  The present invention relates to a switching power supply suitable for the configuration of a multi-output power supply system, and more particularly to a switching power supply capable of synchronizing a switching frequency from the outside.

  In a multi-output type power supply system configured by combining a plurality of individual switching power supply devices according to a plurality of loads having different properties, a switching beat is generated due to a difference in switching frequency of each switching power supply device. For example, when two switching power supply devices operate at the switching frequencies f1 and f2, a switching beat having a frequency corresponding to the frequency difference “f1−f2” is generated. In order to avoid this, it is necessary to synchronize the switching frequency and switching timing of the individual switching power supply devices.

Therefore, conventionally, as described in Patent Document 1, a plurality of control devices having a master / slave function are prepared to drive and control a plurality of switching power supply circuits, one of which is designated as a master control device. Combined with one switching power supply circuit to make a master side switching power supply unit, operate the master side switching power supply unit at a preset clock frequency with independent operation timing, and combine other slave control units with other switching power supply circuits The slave-side switching power supply devices are operated at the same oscillation frequency as the operation timing synchronized with the master-side switching power supply device by receiving the synchronization signal from the master-side switching power supply device. .
Japanese Patent Laid-Open No. 09-163728

  However, when the switching frequency is controlled by synchronizing the clocks of the individual switching power supply devices, it is necessary to separate the master switching power supply device and the slave switching power supply device in advance.

  However, when the switching power supply that starts first among the individual switching power supplies is switched, or when the order in which the individual switching power supplies start is adjusted during the design or at the end, the master side switching There was a problem that the power supply device and the slave side switching power supply device could not be fixed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a switching power supply device that solves the above-mentioned problems by allowing individual switching power supply devices in configuring a multi-output power supply system to be freely set or changed to a master side or a slave side. That is.

  To achieve the above object, the invention according to claim 1 is a switching power supply comprising a switching power supply circuit that outputs an alternating voltage, and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit. A switching power supply circuit that switches the power transistor for generating the AC voltage; an oscillator that generates an oscillation signal and a clock to be supplied to the switching control circuit; and an oscillation signal that the oscillator oscillates as an external input clock A clock synchronization circuit to be synchronized and an external input clock is input from the clock input / output terminal when the setting signal of the setting terminal is the first logic value, and a clock oscillated by the oscillator is input to the clock input / output when the setting signal is the second logic value The clock switcher output from the terminal to the outside and the setting signal of the setting terminal When the first logical value exceeds a reference voltage, the phase shift amount of the external input clock is input to the clock synchronization circuit as one of the first shift amount or the second shift amount, and the setting signal of the setting terminal is A clock phase shift circuit for inputting the phase of the external input clock to the clock synchronization circuit as the other of the first shift amount or the second shift amount when the first logical value is less than the reference voltage. It is characterized by doing.

  According to a second aspect of the present invention, in the switching power supply device according to the first aspect, the clock switch includes a first buffer that transmits / cuts off a clock output from the oscillation circuit toward the clock input / output terminal. A second buffer for transmitting / cutting off an external input clock input to the clock input / output terminal to a clock input side of the clock phase shift circuit; and the second buffer when the setting terminal is at the first logic value. And the first buffer is controlled to be cut off, and the second buffer is controlled to be cut off and the first buffer is controlled to be transmitted when the setting terminal is at the second logical value. And the clock phase shift circuit is configured such that the phase of the external input clock input from the clock switch is the first shift amount. A first phase shift circuit to shift, a second phase shift circuit to shift by the second shift amount, and the first phase when the setting terminal has the first logic value and exceeds the reference voltage. One of the shift circuit or the second phase shift circuit is operated and the other is inactivated, and when the setting terminal is at the first logic value and less than the reference voltage, the one is inactivated and the other And a comparator for operating the device.

  The invention according to claim 3 is a switching power supply comprising a switching power supply circuit that outputs an alternating voltage and a rectifying / smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit, wherein the switching power supply circuit includes the alternating voltage. A switching control circuit for switching a power transistor for generation, an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit, a clock synchronization circuit for synchronizing an oscillation signal oscillated by the oscillator with an external input clock, A clock switch for outputting a clock oscillated by an oscillator to a clock input / output terminal or inputting the external input clock input from the clock input / output terminal to the clock synchronization circuit; The external input to the clock input / output terminal A clock input determination circuit that waits for a predetermined time in order to detect a power clock, and when the external input clock is detected within the predetermined time, the clock input determination circuit sets the clock switch for clock input. When the external input clock is supplied to the clock synchronization circuit and the external input clock is not detected within the predetermined time, the clock switch is switched for clock output and the clock output from the oscillator is Output from the clock input / output terminal to the outside.

  The invention according to claim 4 is a switching power supply comprising a switching power supply circuit that outputs an alternating voltage and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit, wherein the switching power supply circuit includes the alternating voltage. A switching control circuit for switching a power transistor for generation, an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit, a clock synchronization circuit for synchronizing an oscillation signal oscillated by the oscillator with an external input clock, and a control A clock switch that is temporarily switched for clock input for inputting the external input clock that is input from the clock input / output terminal by inputting a start signal from the terminal, and a clock that is input by the start signal from the control terminal Said switched primarily for input A clock input detection circuit that waits for a predetermined time to detect the external input clock output from the lock switch, and the clock input detection circuit detects the external input clock within the predetermined time, A clock switch is fixed for clock input and the external input clock is supplied to the clock synchronization circuit, and when the external input clock is not detected within the predetermined time, the clock switch is switched for clock output, The clock output from the oscillator is output to the outside from the clock input / output terminal.

  The invention according to claim 5 is a switching power supply device comprising a switching power supply circuit that outputs an alternating voltage and a rectifying / smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit, wherein the switching power supply circuit includes the alternating voltage. A switching control circuit for switching a power transistor for generation, an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit, a clock synchronization circuit for synchronizing an oscillation signal oscillated by the oscillator with an external input clock, A clock switch for outputting a clock oscillated by an oscillator to a clock input / output terminal or inputting the external input clock input from the clock input / output terminal to the clock synchronization circuit; External input to clock input / output terminal A current detection / CK switching control circuit that waits for a predetermined time to detect a current and a constant current source, and the current detection / CK switching control circuit detects the external input current within the predetermined time. Switching the clock switch for clock input, supplying the external input clock input from the clock input / output terminal to the clock synchronization circuit, and not detecting the external input current within the predetermined time, After the current from the constant current source is output from the clock input / output terminal for a predetermined time, the clock switch is switched for clock output, and the clock output from the oscillator is output from the clock input / output terminal to the outside. It is characterized by that.

  According to the switching power supply device of the invention according to claims 1 to 5, the on / off timing of the power transistor of the switching power supply device is synchronized with the external input clock, and the on / off of the power transistor of the other switching power supply device It is possible to synchronize the OFF timing with a clock output from the switching power supply device. For this reason, when a multi-output type power supply system is configured by commonly connecting clock input / output terminals of a plurality of switching power supply devices, a clock is output from any one switching power supply device and the clock is output to the other switching power supply devices. By using the input, the switching frequency and switching timing of all the switching power supply devices can be synchronized. Therefore, the configured multi-output power supply system can suppress the occurrence of beat noise by combining the switching frequency and the switching timing only within the multi-output power supply system without receiving a clock from outside the system. it can. In addition, the individual switching power supply devices do not need to be integrated at one place, and the switching power supply devices can be arranged near the load.

  According to the switching power supply device of the first and second aspects of the present invention, since the clock input / output can be set by the setting terminal, the multi-output power supply system is configured by the first to nth switching power supply devices. In the first activation timing, the first switching power supply device is set to clock output (master side), the other switching power supply devices are set to clock input (slave side), and the second activation timing is set to the second output timing. Set the clock input / output arbitrarily by controlling the setting terminal according to the start timing so that the switching power supply is clock output (master side) and the other switching power supply is clock input (slave side) The switching power supply on the master side and slave side can be arbitrarily changed. On the slave side, the phase of the clock used for power transistor switching can be shifted with respect to the external input clock by setting the setting terminal, so that the power transistors of multiple switching power supplies are turned on simultaneously. The phenomenon that the input power supply is reduced can be avoided. Further, since the clock input / output setting of the clock and the phase shift amount of the external input clock can be set simultaneously at the setting terminal, there is an advantage that it is not necessary to increase the number of pins of the control IC of the switching power supply circuit.

  According to the switching power supply device of the inventions according to claims 3 to 5, since the start timing of each switching power supply device can be set independently using the control terminal, the clock input / output terminals of the plurality of switching power supply devices are provided. When a multi-output power supply system is configured with a common connection, the switching power supply with the earliest start-up timing outputs the clock from the clock input / output terminal (master side), and the switching power supply that is started second or later The input from the clock input / output terminal (slave side) is performed, and the switching power supply activated after the second is synchronized with the switching frequency and switching timing of the switching power supply activated first. That is, among the plurality of switching power supply devices, the first switching power supply device activated is the master side, and the subsequent switching power supply device is the slave side. The side switching power supply can be arbitrarily changed.

<First embodiment>
FIG. 1 is a diagram showing a configuration of a switching power supply apparatus 100 according to a first embodiment of the present invention. This switching power supply device 100 includes a switching power supply circuit 10A made of an IC, a rectifying / smoothing circuit made up of a diode D1, an inductor L1, and a capacitor C1 connected to the output side thereof, and an output voltage VOUT as a feedback signal. It consists of pressure resistors R1 and R2.

  The switching power supply circuit 10A includes a power transistor 11 that switches the input voltage VIN, a switching control circuit 12 that drives the power transistor 11, and supplies an oscillation signal (such as a triangular wave) P1 to the switching control circuit 12 or a clock for external output. An oscillator 13 that outputs CK1, a clock synchronization circuit 14 that supplies the oscillator 13 with a synchronization signal P2 synchronized with an external input clock and synchronizes the oscillation signal P1 with the external input clock, and a clock switch 15 that switches the input and output of the clock A clock input / output terminal 16 connected to the clock switch 15, a clock phase shift circuit 17 that inverts the phase of the external input clock output from the clock switch 15 or transmits it as it is to the clock synchronization circuit 14, and Clock switch Comprising a 5 and a setting pin 18 for controlling the clock phase shift circuit 17.

  As shown in FIG. 2, the clock switch 15 transmits / blocks the clock CK1 output from the oscillator 13 with respect to the clock input / output terminal 16 and the external input clock input from the clock input / output terminal 16 as a clock phase. A buffer 152 that transmits / blocks to / from the shift circuit 17 and an inverter as a control circuit that controls one of the buffers 151 and 152 to transmit and controls the other to block according to the logical value of the signal applied to the setting terminal 18. It consists of INV1 and INV2.

  In this clock switch 15, when the setting terminal 18 is set to “L”, the buffer 151 is transmitted, the buffer 152 is cut off and the clock 152 is switched for clock output, and the clock CK 1 generated by the oscillator 13 is applied to the clock input / output terminal 16. Output. When the setting terminal 18 is set to “H”, the buffer 151 is cut off, the buffer 152 is transmitted and switched for clock input, and an external input clock input to the clock input / output terminal 16 is output to the clock phase shift circuit 17. To do.

  As shown in FIG. 3, the clock phase shift circuit 17 includes NOR circuits NOR1 and NOR2, an AND circuit AND1, a comparator 171 in which the reference voltage V1 is set, and a bias circuit 172 including a current source I1 and a resistor R3. Prepare. The NOR circuits NOR1 and NOR2 constitute a first phase shift circuit, and the AND circuit AND1 and NOR circuit NOR2 constitute a second phase shift circuit.

  The clock phase shift circuit 17 is configured such that when the setting terminal 18 is “H” and the voltage of the inverting input terminal of the comparator 171 is lower than the reference voltage V1 by the bias circuit 172, that is, the setting terminal 18 is When open, the output of the comparator 171 becomes “H”, the NOR circuit NOR1 closes the gate, and the AND circuit AND1 opens the gate. Therefore, the external input clock CK2 input from the clock switch 15 passes through the AND circuit AND1 and the NOR circuit NOR2, so that the phase shift amount = 180 degrees and is output to the clock synchronization circuit 14 as the clock CK3.

  On the other hand, when the setting terminal 18 is “H” and the voltage of the inverting terminal of the comparator 171 is higher than the reference voltage V1 by the bias circuit 172, that is, the setting terminal 18 is connected to the high potential power supply terminal. When the output of the comparator 171 is "L", the NOR circuit NOR1 opens the gate and the AND circuit AND1 closes the gate. Therefore, the external input clock CK2 input from the clock switch 15 passes through the NOR circuits NOR1 and NOR2, so that the phase shift amount = 0 degree and is output to the clock synchronization circuit 14 as the clock CK3.

  From the above, when the setting terminal 18 is set to “L”, the switching power supply device 100 of the present embodiment outputs the clock CK1 oscillated by the oscillator 13 from the clock switch 15 to the outside. At this time, the switching control circuit 12 is controlled by the oscillation signal P1 (synchronized with the clock CK1) oscillated by the oscillator 13, the power transistor 11 is switched, the input voltage VIN is turned on / off, and an alternating current component having a predetermined frequency is generated. Is done. This AC component is rectified by the diode D1, smoothed by the coil L1 and the capacitor C1, and output. The output voltage VOUT at this time is divided by the resistors R1 and R2 and fed back to the switching control circuit 12, compared with a set voltage (not shown), and the power transistor 11 is controlled according to the error component. The output voltage VOUT is controlled to a constant voltage corresponding to the set voltage.

  On the other hand, when the setting terminal 18 is set to “H”, the external input clock input to the clock input / output terminal 16 is input to the clock phase shift circuit 17 via the clock switch 15 as the clock CK2. At this time, when the voltage of the setting terminal 18 is higher than the reference voltage V1, the clock phase shift circuit 17 is set to the phase shift amount = 0 degree, so that the clock CK2 is directly used as the clock CK3 in the clock synchronization circuit 14. The oscillation signal P1 taken in and oscillated by the oscillator 13 is synchronized with the synchronization signal P2 from the clock synchronization circuit 14. As a result, the power transistor 11 performs switching in synchronization with the external input clock. When the voltage at the setting terminal 18 is lower than the reference voltage V1, the clock phase shift circuit 17 is set to the phase shift amount = 180 degrees, so that the clock CK2 is inverted by 180 degrees and is sent to the clock synchronization circuit 14 as the clock CK3. The oscillation signal P1 taken in and oscillated by the oscillator 13 is synchronized with the synchronization signal P2 from the clock synchronization circuit 14. As a result, the power transistor 11 performs switching in synchronization with the phase difference of 180 degrees with respect to the external input clock.

  FIG. 4 is a diagram showing a three-output type power supply system using three switching power supply devices 100 of the present embodiment. In the switching power supply devices 100A to 100C, the clock input / output terminal 16 is commonly connected, and the external power supply Vs is commonly input as the power supply voltages VDD and VIN. Here, the switching power supply device 100A grounds the setting terminal 18 and sets it to “L”, and outputs the clock from the clock input / output terminal 16 to the outside. Further, the switch power supply device 100B connects the setting terminal 18 to the power supply Vs and sets it to the “H” level, and inputs an external input clock output from the clock input / output terminal 16 of the switching power supply device 100A to the clock input / output terminal 16. ing. At this time, the phase shift amount of the clock phase shift circuit 17 of the switch power supply apparatus 100B is 0 degree. Further, the switch power supply device 100C opens the setting terminal 18 to set it to the “H” level, and the clock input / output terminal 16 receives the external input clock output from the clock input / output terminal 16 of the switching power supply device 100A. At this time, the clock phase shift circuit 17 of the switch power supply apparatus 100C has a phase shift amount = 180 degrees.

  As a result, the switching power supply device 100A becomes the master side, and the switching power supply devices 100B and 100C become the slave side. The switching power supply devices 100A and 100B perform switching in synchronization with the power transistor 11 at the same frequency (the clock CK1 of the switching power supply device 100A). The power transistor 11 of the switching power supply device 100C also performs switching with the same frequency but with a phase difference of 180 degrees. If it does in this way, since switching frequency of all the switching power supply devices 100A-100C synchronizes, generation | occurrence | production of beat noise can be suppressed. In addition, since the number of power transistors 11 that are simultaneously turned on is reduced from three to two as compared to the case where all the switching power supply devices 100A to 100C are switched at the same phase (the clock CK1 of the switching power supply device 100A), The total power supply current due to the input voltage VIN flowing at the same time is reduced, and the power supply capacity of the input voltage VIN (here, the power supply Vs) can be reduced.

<Second embodiment>
FIG. 5 is a diagram showing the configuration of the switching power supply apparatus 200 according to the second embodiment of the present invention. This switching power supply device 200 includes a switching power supply circuit 10B made of an IC, a rectifying / smoothing circuit made up of a diode D2, an inductor L2, and a capacitor C2 connected to the output side thereof, and an output voltage VOUT as a feedback signal. It consists of pressure resistors R4 and R5.

  In the switching power supply circuit 10B, the same components as those shown in the switching power supply device 10A of FIG. Reference numeral 19 denotes a clock input determination circuit, and 20 denotes a control terminal to which an activation signal is input. The switching control circuit 12A soft-starts when an activation signal P3 from the control terminal 20 is input, and outputs a standby signal P4 for a certain period thereafter. The clock input determination circuit 19 determines whether or not a clock is input from the clock input / output terminal 16 during the period when the standby signal P4 is input from the switching control circuit 12A. Are switched for clock input, and an external input clock is input to the clock synchronization circuit 14. When the clock input cannot be determined within a certain time during which the standby signal P4 is input, the clock switch 15 is switched for clock output, and the clock CK1 from the oscillator 13 is output to the clock input / output terminal 16. The standby signal P4 is canceled when the clock switch 15 is finally switched to clock input or clock output.

  FIG. 6 is a flowchart of the operation of the switching power supply apparatus 200 of FIG. When the activation signal P3 is input to the control terminal 20, the switching control circuit 12A is activated (S21), the standby signal P4 is output to the clock input determination circuit 19, and the clock input determination circuit 19 enters the clock input standby state (S22). .

  If it is determined that the clock is input from the clock input / output terminal 16 within the period during which the standby signal P4 is input (S23-YES), the clock switch 15 is switched for clock input (S24). The external input clock CK2 is input to the synchronization circuit 14 (S25), the oscillator 13 outputs the oscillation signal P1 in synchronization with the external input clock CK2, and the switching control circuit 12A synchronizes the power transistor 11 with the external input clock CK2. Switching.

  When it is not determined that the clock is input from the clock input / output terminal 16 within the period when the standby signal P4 is input to the clock input determination circuit 19 (S23-NO), the clock switch 15 is switched to clock output. (S26) The clock CK1 oscillated by the oscillator 13 is output to the outside from the clock input / output terminal 16 (S27).

  The switching power supply device 200 of this embodiment uses a plurality of the switching power supply devices 200 to form a multi-output power supply system in the same manner as shown in FIG. The switching power supply device that outputs a clock from the output terminal 16, that is, the switching power supply device that is activated first is the master side, the switching power supply device that is subsequently activated is the slave side, and the slave side operates in synchronization with the master side. Note that the switching power supply device 200 to which the activation signal P3 is not input does not operate.

<Third embodiment>
FIG. 7 is a diagram showing a configuration of a switching power supply apparatus 300 according to the third embodiment of the present invention. This switching power supply apparatus 300 includes a switching power supply circuit 10C formed of an IC, a rectifying / smoothing circuit formed of a diode D3, an inductor L3, and a capacitor C3 connected to the output side thereof, and a component that detects an output voltage VOUT as a feedback signal. It comprises pressure resistors R6 and R7.

  In the switching power supply circuit 10C, the same components as those shown in the switching power supply device 10A of FIG. 1 and the switching power supply device 10B of FIG. Reference numeral 15A denotes a clock switch that is switched for clock input for a predetermined time when the activation signal P3 is input, and 21 is a clock detection circuit that detects an external input clock. When the standby signal P4 is input from the switching control circuit 12A, the clock detection circuit 21 enters a clock input standby state for a predetermined time. When an external input clock is detected during this period, the clock switch 15A is fixed for clock input and is not detected. If so, switch to clock output. The clock switch 15A is the same as the clock switch 15 shown in FIG. 2, but the setting terminal 20 and the detection output side of the clock detection circuit 21 are connected to the input side of the inverter INV1. The standby signal P4 is canceled when the clock switch 15A is finally switched to clock input or clock output.

  FIG. 8 is a flowchart of the operation of the switching power supply apparatus 300 of FIG. When the activation signal P3 is input to the control terminal 20, the switching control circuit 12A is activated (S31), and the clock switch 15A is switched to the clock input side (S32). Further, the switching control circuit 12A outputs a standby signal P4 to the clock detection circuit 21, and the clock detection circuit 21 enters a clock input standby state for a predetermined time (S33).

  When the clock detection circuit 21 detects that the clock is input from the clock input / output terminal 16 within a predetermined time after the standby signal P4 is input (YES in S34), the clock synchronization circuit 14 receives the external input clock. Is input as the clock CK2 (S35), the oscillator 13 outputs the oscillation signal P1 in synchronization with the external input clock CK2, and the switching control circuit 12A switches the power transistor 11 in synchronization with the clock CK2.

  When the clock input detection circuit 21 does not detect that the clock is input from the clock input / output terminal 16 within the predetermined time (S34-NO), the clock switch 15 is switched for clock output (S36), and the oscillator The clock CK1 oscillating at 13 is output from the clock input / output terminal 16 to the outside (S37).

  The switching power supply apparatus 300 of this embodiment also uses a plurality of the switching power supply apparatuses 300 to form a multi-output power supply system as shown in FIG. The switching power supply device that outputs a clock from the output terminal 16, that is, the switching power supply device that is activated first is the master side, the switching power supply device that is subsequently activated is the slave side, and the slave side operates in synchronization with the master side. Note that the switching power supply device 300 to which the activation signal P3 is not input does not operate.

<Fourth embodiment>
FIG. 9 is a diagram showing a configuration of a switching power supply apparatus 400 according to the fourth embodiment of the present invention. The switching power supply device 400 includes a switching power supply circuit 10D formed of an IC, a rectifying / smoothing circuit formed of a diode D4, an inductor L4, and a capacitor C4 connected to the output side thereof, and a component that detects the output voltage VOUT as a feedback signal. It comprises pressure resistors R8 and R9.

  In the switching power supply circuit 10D, the same components as those shown in the switching power supply device 10A of FIG. 1 and the switching power supply device 10B of FIG. 22 is a current detection / CK switching control circuit, and I2 is a constant current source. When the standby signal P4 is input from the switching control circuit 12A, the current detection / CK switching control circuit 22 enters an input current detection standby state for a certain period of time for the current flowing from the clock input / output terminal 16, and the input current is detected. Then, it is determined that the clock input is detected, and the clock switch 15 is switched for clock input. When the current cannot be detected within the standby time for detecting the input current, the constant current source I2 is driven for a predetermined time and the current from the constant current source I2 is output to the outside from the clock input / output terminal 16. The standby signal P4 is canceled when the clock switch 15 is switched for clock input or clock output.

  FIG. 10 is a flowchart of the operation of the switching power supply apparatus 400 of FIG. When the activation signal P3 is input to the control terminal 20, the switching control circuit 12A is activated (S41), the standby signal P4 is output to the current detection / CK switching control circuit 22, and the current detection / CK switching control circuit 22 is only for a certain time. A standby state for detecting an input current to the clock input / output terminal 16 is entered (S42).

  If the current input to the clock input / output terminal 16 is detected during the standby of the input current detection (S44-YES), it is determined as an external input clock, and the clock switch 15 is switched for clock input. (S43) The external input clock is input to the clock synchronization circuit 14 as the clock CK2 (S45), the oscillator 13 outputs the oscillation signal P1 in synchronization with the external input clock CK2, and the switching control circuit 12A is the power transistor 11 Are switched in synchronization with the external input clock CK2.

  When the input current is not detected during the standby of the input current detection (S44-NO), the constant current source I2 is driven, and the current from the constant current source I2 is output from the clock input / output terminal 16 for a predetermined time (S46). ). Thereafter, the clock switch 15 is switched for clock output (S47), and the clock CK1 oscillated by the oscillator 13 is output from the clock input / output terminal 16 to the outside (S48).

  In the switching power supply device 400 of this embodiment, when a multi-output type power supply system is configured using a plurality of the switching power supply devices 400 as shown in FIG. 4, the clock signal is first input by the activation signal P3 input to the control terminal 20. The switching power supply device that outputs current from the output terminal 16, that is, the switching power supply device that is activated first is the master side, the switching power supply device that is subsequently activated is the slave side, and the slave side operates in synchronization with the master side. Note that the switching power supply device 400 to which the activation signal P3 is not input does not operate.

It is a block diagram which shows the structure of the switching power supply device of the 1st Example of this invention. It is a block diagram which shows the internal structure of the clock switcher of the switching power supply device of FIG. FIG. 2 is a block diagram showing an internal configuration of a clock phase shift circuit of the switching power supply device of FIG. 1. It is a block diagram which shows the structure of the 3 output type power supply system comprised with the switching power supply device of FIG. It is a block diagram which shows the structure of the switching power supply device of the 2nd Example of this invention. It is a flowchart of operation | movement of the switching power supply device of FIG. It is a block diagram which shows the structure of the switching power supply device of the 3rd Example of this invention. It is a flowchart of operation | movement of the switching power supply device of FIG. It is a block diagram which shows the structure of the switching power supply device of the 4th Example of this invention. 10 is a flowchart of the operation of the switching power supply device of FIG. 9.

Explanation of symbols

100 to 400: switching power supply device 10A to 10D: switching power supply circuit 11: power transistor, 12: switching control circuit, 13: oscillator, 14: clock synchronization circuit, 15, 15A: clock switch, 16: clock input / output terminal, 17: Clock phase shift circuit, 18: Setting terminal, 19: Clock input determination circuit, 20: Control terminal, 21: Clock detection circuit, 22: Current detection / CK switching control circuit

Claims (5)

In a switching power supply device comprising a switching power supply circuit that outputs an alternating voltage and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit,
A switching control circuit for switching the power transistor for generating the AC voltage; an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit; and an oscillation signal generated by the oscillator for an external input clock. A clock synchronization circuit for synchronizing with the external input clock, an external input clock is input from the clock input / output terminal when the setting signal of the setting terminal is the first logic value, and a clock oscillated by the oscillator is input to the clock when the setting signal of the setting terminal is the second logic value. A clock switch that outputs from an output terminal to the outside; and a phase shift amount of the external input clock when the setting signal of the setting terminal exceeds the reference voltage with the first logic value, One of the shift amounts is input to the clock synchronization circuit, and the setting signal of the setting terminal is the first logic. And a clock phase shift circuit for inputting the phase of the external input clock to the clock synchronization circuit as the other of the first shift amount or the second shift amount when the voltage is lower than the reference voltage. Switching power supply. The switching power supply device according to claim 1,
The clock switch includes a first buffer for transmitting / cutting a clock output from the oscillation circuit in the direction of the clock input / output terminal, and an external input clock input to the clock input / output terminal of the clock phase shift circuit. A second buffer for transmitting / blocking to a clock input side, and when the setting terminal is at the first logical value, the second buffer is controlled to be transmitted and the first buffer is controlled to be blocked, and the setting A control circuit for controlling the second buffer to be shut off when the terminal is at the second logic value and controlling the first buffer to transmit,
The clock phase shift circuit includes a first phase shift circuit that shifts the phase of the external input clock input from the clock switch by the first shift amount, and a second phase that shifts the phase by the second shift amount. When the shift circuit and the setting terminal are at the first logic value and exceed the reference voltage, one of the first phase shift circuit or the second phase shift circuit is operated and the other is not operated, A comparator that disables the one and operates the other when the setting terminal is at the first logical value and less than the reference voltage;
The switching power supply device characterized by the above-mentioned. In a switching power supply device comprising a switching power supply circuit that outputs an alternating voltage and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit,
A switching control circuit for switching the power transistor for generating the AC voltage; an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit; and an oscillation signal generated by the oscillator for an external input clock. A clock synchronizing circuit that synchronizes with the clock, a clock switch that outputs the clock oscillated by the oscillator to the clock input / output terminal, or inputs the external input clock input from the clock input / output terminal to the clock synchronizing circuit, and a control terminal A clock input determination circuit that waits for a predetermined time to detect the external input clock that is input to the clock input / output terminal when a start signal is input from
When the external input clock is detected within the predetermined time, the clock input determination circuit switches the clock switch for clock input and supplies the external input clock to the clock synchronization circuit. When the external input clock is not detected within, the clock switch is switched for clock output, and the clock output from the oscillator is output to the outside from the clock input / output terminal.
The switching power supply device characterized by the above-mentioned. In a switching power supply device comprising a switching power supply circuit that outputs an alternating voltage and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit,
A switching control circuit for switching the power transistor for generating the AC voltage; an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit; and an oscillation signal generated by the oscillator for an external input clock. A clock synchronization circuit that synchronizes with the clock, a clock switch that is temporarily switched for clock input for inputting the external input clock that is input from the clock input / output terminal when a start signal is input from the control terminal, and the control terminal A clock input detection circuit that waits for a predetermined time in order to detect the external input clock output from the clock switcher that is temporarily switched for clock input when a start signal is input;
When the external input clock is detected within the predetermined time, the clock input detection circuit fixes the clock switch for clock input and supplies the external input clock to the clock synchronization circuit. When the external input clock is not detected, the clock switch is switched for clock output, and the clock output from the oscillator is output to the outside from the clock input / output terminal.
The switching power supply device characterized by the above-mentioned. In a switching power supply device comprising a switching power supply circuit that outputs an alternating voltage and a rectifying and smoothing circuit that rectifies and smoothes the output voltage of the switching power supply circuit,
A switching control circuit for switching the power transistor for generating the AC voltage; an oscillator for generating an oscillation signal and a clock to be supplied to the switching control circuit; and an oscillation signal generated by the oscillator for an external input clock. A clock synchronizing circuit that synchronizes with the clock, a clock switch that outputs the clock oscillated by the oscillator to the clock input / output terminal, or inputs the external input clock input from the clock input / output terminal to the clock synchronizing circuit, and a control terminal A current detection / CK switching control circuit that waits for a predetermined time in order to detect an external input current input to the clock input / output terminal when a start signal is input from, and a constant current source,
When the current detection / CK switching control circuit detects the external input current within the predetermined time, the current detection / CK switching control circuit switches the clock switch for clock input and outputs the external input clock input from the clock input / output terminal. When supplying the clock synchronization circuit and not detecting the external input current within the predetermined time, the clock switch is clocked after outputting the current from the constant current source from the clock input / output terminal for a predetermined time. Switching to output, outputting the clock output from the oscillator to the outside from the clock input / output terminal,
The switching power supply device characterized by the above-mentioned.

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