JP5589518B2 - Semiconductor integrated circuit and DC-DC converter using the same - Google Patents

Description

  The present invention relates to a semiconductor integrated circuit including a switching circuit having a full bridge configuration, capable of transmitting and receiving an external signal, and usable for a power supply device regardless of an insulating type / non-insulating type, and a DC-DC converter using the same. Is.

  In the isolated DC-DC converter, the primary and secondary circuits are insulated from each other by a transformer in order to cope with different ground potentials in the primary circuit and the secondary circuit or to satisfy safety standards. When controlling the output voltage and output current on the secondary side, they are detected and fed back to the primary side to control the switching circuit on the primary side. Insulation between them is required.

When a synchronous rectifier circuit is used on the secondary side, the secondary side synchronous rectification is performed immediately before the main switch is turned on in order to prevent both the main switch and the commutation side synchronous rectifier from being turned on and a through current flowing. It is necessary to turn off the commutation side synchronous rectifier of the circuit, and it is necessary to transmit a signal indicating the timing immediately before the main switch is turned on from the primary side to the secondary side to control the switching timing of the secondary side synchronous rectifier. is there. (See Patent Document 1)
Here, FIG. 1 shows a basic configuration of an insulation type DC-DC converter disclosed in Patent Document 1. In FIG.

  In FIG. 1, the main switch 2 is subjected to switching control according to a control signal output from the primary side control circuit 5. The primary side control circuit 5 detects the output voltage Vo through the insulation circuit 10, and outputs a signal C1 for controlling the duty ratio of the main switch 2 based on this. Further, the control signal C1 is also transmitted to the secondary side through the drive circuits 7 and 8 and the transformer 9 to become the control signal C2, and the control signal C2 is supplied to the secondary side control circuit 21. The control signal C2 supplied to the secondary side control circuit 21 is applied to the input terminal of the drive circuit 13 and the gate electrode of the transistor 15, whereby the rectification side synchronous rectifier 3 is driven in phase with the main switch 2 and is commutated. The side synchronous rectifier 4 is driven in a phase opposite to that of the main switch 2.

  Here, the timing shift between the control signal C1 and the control signal C2 caused by the interposition of the drive circuits 7 and 8 and the transformer 9, and the turn-off delay time of the MOSFET constituting the commutation side synchronous rectifier are the main switch Is adjusted by a delay circuit 11 that delays the turn-on timing.

JP 2002-272097 A

  As shown in FIG. 1, when a synchronous rectifier circuit is used on the secondary side, the signal is transmitted with the primary and secondary sides insulated, including means for feeding back the output voltage detection signal to the primary side. There is a problem that the circuit configuration becomes complicated because at least two means are required.

  Another problem is that in recent years ICs have been used for control circuits. If the primary side control circuit and the secondary side control circuit have a unique design, two types of application specific ICs (ASICs) can be used. There was a problem that it had to be manufactured and productivity and economy were poor.

  Accordingly, an object of the present invention is to provide a full-bridge switching circuit, which can transmit and receive external signals, and in the case of an insulation type, two ICs having the same hardware configuration are used on the primary side and the secondary side. An object of the present invention is to provide a semiconductor integrated circuit that can be used for a power supply device and can be applied to a non-insulated type, and a DC-DC converter using the same.

  An insulated DC-DC converter according to the present invention includes a first DC voltage unit to which a predetermined DC voltage is applied, a second DC voltage unit, a GND terminal connected to a reference potential, and a first switch circuit. A first series circuit composed of S1 and a second switch circuit S2, a second series circuit composed of a third switch circuit S3 and a fourth switch circuit S4, and the first to fourth switch circuits; A control unit for controlling the on / off operation of the first switch circuit, a first output terminal for drawing out a connection point between the first switch circuit S1 and the second switch circuit S2, and the third switch circuit. S3 and a second output terminal for drawing out a connection point of the fourth switch circuit S4 to the outside, wherein one end of the first series circuit is the first DC voltage unit Vdr1 is connected to the second series circuit Is connected to the second DC voltage unit Vdr2, the other end of the first series circuit and the other end of the second series circuit are both connected to the GND terminal, A reactance element is connected between the output terminal and the second output terminal, and winding voltage detection means (Vdet) for detecting a change in the voltage across the reactance element and at least the first switch circuit S1 are turned on. When the second switch circuit S2 and the third switch circuit S3 are both in the off state, a positive voltage is applied to the reactance element, or the second switch circuit (S2) is turned on. And when the first switch circuit (S1) and the fourth switch circuit (S4) are both in an off state, a negative voltage is applied to the reactance element, An exciting current is passed through the reactance element to generate a pulse voltage, and the pulse voltage is transmitted to the outside as an edge signal. At least both the first switch circuit S1 and the second switch circuit S2 are in an off state. In some cases, an external edge signal can be received by detecting a pulse voltage generated in the reactance element by the winding voltage detection terminal.

  Further, the semiconductor integrated circuit further controls a third output terminal that outputs a voltage input from the first DC voltage unit, and whether or not to output a voltage to the third output terminal. A sub-driver circuit, and a turn-on and turn-off operation of the sub-driver circuit is controlled by the control unit. The control unit has a square wave voltage generated at the second output terminal and a third output terminal. The first to fourth switch circuits and the sub-driver circuit are controlled so that the generated square wave voltages have a complementary relationship with each other with a period in which both are at a low level.

  Further, the semiconductor integrated circuit is an isolated switching power supply device used in a primary side control circuit and a secondary side control circuit, respectively, and includes a DC power supply, at least one set of primary winding and secondary winding. A transformer having at least one power switch element for controlling whether or not to apply a DC voltage supplied from the DC power source to the primary winding, and at least one synchronization connected to the secondary winding The semiconductor integrated circuit comprising at least a rectifier circuit including a rectifier circuit and an output filter circuit for smoothing the output of the rectifier circuit, and having at least a primary winding and a secondary winding and disposed on the primary side A semiconductor integrated circuit disposed on the primary side using a signal transmission transformer in which the secondary winding is connected to the semiconductor integrated circuit disposed on the secondary side as a reactance element. When Between the semiconductor integrated circuit arranged in the secondary side, a pulse signal is transmitted bidirectionally, and controlling the drive timing of the power switching element and the synchronous rectifier.

  Furthermore, the semiconductor integrated circuit according to claim 1 or 2 is used as a control circuit, and a DC power supply, at least one inductance element, and a DC voltage supplied from the DC power supply are applied to the inductance element. A non-insulated switching power supply comprising: at least one power switch element that controls whether or not; a rectifier circuit including at least one synchronous rectifier; and an output filter circuit that smoothes an output of the rectifier circuit, The power switch element or the synchronous rectifier is composed of a field effect transistor, the source terminal of the field effect transistor is floating from the ground potential of the control circuit, and an edge signal is connected between the gate and the source of the field effect transistor. To a square wave signal conversion circuit is connected, and from the semiconductor integrated circuit An edge signal transmitted through the lance in the converted square wave signal by the converting circuit, the field effect transistor is characterized in that it is driven.

The present invention
(A) A programmable semiconductor element having a bidirectional signal transmission function can be provided while controlling driving of the power semiconductor element.
(B) Regardless of insulation type / non-insulation type, it can be applied as a control circuit for power supply devices of various topologies.
(C) When used in an insulated DC-DC converter, the same hardware semiconductor elements can be used on the primary side and the secondary side, which contributes to a reduction in control IC development costs and manufacturing costs.

It is a figure which shows the basic composition of the insulation type DC-DC converter shown by patent document 1. FIG. 3 is an internal block diagram of a control IC 101 according to the first embodiment. FIG. It is an example of a circuit of an insulation type DC-DC converter using control IC concerning a 1st embodiment. It is a wave form diagram of each part per switching period. It is operation | movement explanatory drawing inside control IC in the time t0-t1 area. It is operation | movement explanatory drawing inside control IC in time t1. It is operation | movement explanatory drawing inside control IC in the time t1-t2 area. It is operation | movement explanatory drawing inside control IC in time t2. It is operation | movement explanatory drawing inside control IC in the time t2-t3 area. It is operation | movement explanatory drawing inside control IC in the time t3-t4 area. It is operation | movement explanatory drawing inside control IC in the time t4-t5 area. It is operation | movement explanatory drawing inside control IC in time t5. It is operation | movement explanatory drawing inside control IC in the time t5-t6 area. It is operation | movement explanatory drawing inside control IC in time t6. It is operation | movement explanatory drawing inside control IC in the time t6-t7 area. It is operation | movement explanatory drawing inside control IC in the time t7-t8 area. It is an internal block diagram of control IC101 concerning a 2nd embodiment. 2 is a circuit example of a non-insulated step-down DC-DC converter using the control IC according to the first embodiment. 3 is a circuit example of a non-insulated step-up DC-DC converter using the control IC according to the first embodiment. 3 is a circuit example of a non-insulated SEPIC converter using the control IC according to the first embodiment.

<< First Embodiment >>
FIG. 2 is an internal block diagram of a semiconductor integrated circuit (hereinafter referred to as a control IC) 101 used for controlling the isolated DC-DC converter according to the first embodiment. The control IC 101 includes at least a first switch circuit S1 composed of a parallel circuit of a first switching element Q1 and a first diode D1, and a second switch composed of a parallel circuit of at least a second switching element Q2 and a second diode. A series circuit composed of a switch circuit S2, a third switch circuit S3 composed of a parallel circuit of at least a third switching element Q3 and a third diode D3, and at least a fourth switching element Q4 and a fourth diode D4. And a digital circuit that outputs a control signal for controlling the turn-on and turn-off of each of the switch circuits S1 to S4.

  A connection point between the first switch circuit S1 and the second switch circuit S2 and a connection point between the third switch circuit S3 and the fourth switch circuit S4 are connected to a first element for connecting an inductance element therebetween. A pulse signal terminal OUT1 and a second pulse signal terminal OUT2 are provided. One end of each of the series circuit composed of the first switch circuit S1 and the second switch circuit S2 and the series circuit composed of the third switch circuit S3 and the fourth switch circuit S4 are commonly connected. The other end connected to the ground terminal GND is connected to the first DC voltage unit Vdr1 and the second DC voltage unit Vdr2. That is, since each of the switch circuits S1 to S4 forms a full bridge type, the first switch circuit S1 and the third switch circuit S3 that are high-side switches are connected via a buffer as a high-side driver. A control signal from the digital control unit is transmitted.

  Further, a connection point between the third switch circuit S3 and the fourth switch circuit S4 is provided with a pulse voltage signal detection terminal Vdet for detecting the potential at the connection point so as to be input to the digital control unit. It is configured.

  Further, for example, a sub-driver for obtaining power from the second DC voltage unit Vdr2 and outputting a second drive signal by a signal output from the digital control unit, and a second driver signal from which the second drive signal is output. 3 signal output terminals OUT3.

  Further, the first comparator COMP1 and the first reference voltage source Vref1 input to the first comparator COMP1 are provided, and the output signal of the first comparator is input to the digital control unit. ing.

  Further, the connection point between the first switch circuit S1 and the second switch circuit S2 and the drive power supply terminal Vlogic of the digital control unit are connected via the ninth diode D9 and the ninth switch circuit S9. The ninth switch circuit S9 is controlled by the digital control unit.

  FIG. 3 shows a circuit diagram according to the first embodiment of an isolated DC-DC converter using the control IC shown in FIG.

  A series circuit including a primary winding Np1 of the transformer T, an eleventh switching element Q11, and a first resistor R1 is connected to both ends of the DC input power source Vin. The eleventh switching element Q11 On the other hand, a series circuit composed of a first capacitor C1 and a twelfth switching element Q12 formed of a P-channel MOSFET is connected in parallel.

  Connected to both ends of the secondary winding Ns1 of the transformer T is a synchronous rectifier circuit including a thirteenth switching element Q13 functioning as a synchronous rectifier for rectification and a fourteenth switching element Q14 functioning as a synchronous rectifier for commutation. Then, a DC voltage is output to the output terminal Vout through a smoothing circuit including the first inductor L1 and the fourth capacitor C4.

  The primary-side control IC 101 obtains a driving voltage from the first DC voltage unit Vdr1 and the second DC voltage unit Vdr2 and controls the eleventh switching element Q11 to control the eleventh switching element Q11. And the second signal output terminal OUT2 are connected to control the twelfth switching element Q12, the control terminal of the twelfth switching element Q12 and the third signal output terminal OUT3 are connected to the third capacitor C3 and The eleventh switching element Q11 is connected to the thirteenth diode D13 through the level shift circuit, and the eleventh switching element Q11 is connected to the eleventh switching element Q11 in order to detect the current flowing through the eleventh switching element Q11 using the first resistor R1 as a current detection resistor. 1 is connected to the feedback signal input terminal FB1, and the first pulse signal terminal OUT1 and the second pulse signal are connected to the feedback signal input terminal FB1. The terminal OUT2, both ends of the primary winding Np2 of the pulse transformer PT is connected. The ground terminal GND is connected to the GND line.

  The secondary side control IC 102 obtains drive voltages from the output voltage obtained by rectifying and smoothing the voltage generated in the secondary winding Ns1 of the transformer T to the drive power supply terminal Vdd, the first DC voltage unit Vdr1, and the second DC voltage unit Vdr2. In order to control the thirteenth switching element Q13, the control terminal of the thirteenth switching element Q13 and the second signal output terminal OUT2 are connected, and in order to control the fourteenth switching element Q14, the fourteenth The control terminal of the switching element Q14 and the third signal output terminal OUT3 are connected, and the output voltage divided by the fourth resistor R4 and the fifth resistor R5, the second resistor R2, the third resistor A combination of the ramp wave signal from the ramp wave forming circuit 103 including the resistor R3, the fourth capacitor C4, and the fifth capacitor C5 is applied to the feedback signal input terminal FB1. Connected to be force, the first pulse signal terminal OUT1 and the second pulse signal terminal OUT2, both ends of the secondary winding Ns2 of the pulse transformer PT is connected. Note that the sixth capacitor C6 functions as a smoothing capacitor.

  Each switch circuit of at least the first switch circuit S1 to the eighth switch circuit S8 is configured by a MOSFET, whereby the first diode D1 to the eighth diode D8 can be replaced with a body diode of the MOSFET. In particular, the eleventh switching element Q11 to the fourteenth switching element Q14, which are power semiconductor elements, are not limited to MOSFETs, and BJT (bipolar junction transistor), IGBT (insulated gate bipolar transistor), and the like can also be applied. In FIG. 3, a P-channel FET is used only for the twelfth switching element Q12, and an N-channel FET is used for the other switching elements. However, these may be properly used as necessary.

  Although details will be described later, the same hardware IC can be used for the primary side control IC 101 and the secondary side control IC 102.

  FIG. 4 shows the drain-source voltage of the eleventh switching element Q11, the gate-source voltages of the first switching element Q1 to the fourth switching element Q4 in one switching cycle of the eleventh switching element Q11, and Each waveform diagram of the voltage across the primary winding Np2 of the pulse transformer PT is shown.

The operation of each part will be described by dividing one switching cycle of the eleventh switching element Q11 into a total of 10 sections from t0 to t8.
[Operations during time t0 to t1]
FIG. 5 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in this section. As shown in FIG. 2, the drive power supply terminal Vlogic of the digital control unit of the primary side control IC 101 and the secondary side control IC 102 has a first switch via a ninth switch circuit S9 and a ninth diode D9. This is because it is connected to the connection point between the circuit S1 and the second switch circuit S2.

  At this time, the first switch circuit S1, the second switch circuit S2, and the third switch circuit S3 are off, and the fourth switch circuit S4 is on. Thereby, the gate-source of the eleventh switching element Q11 connected to the second signal output terminal OUT2 in the primary side control IC 101 is short-circuited by the fourth switch circuit S4 being turned on, No charge is accumulated in the input capacitance Ciss of the eleventh switching element Q11. That is, the eleventh switching element Q11 is in an off state.

  At this time, the source-gate voltage of the twelfth switching element Q12, which is a P-channel FET, is at a negative potential, and is in an on state.

  The same applies to the secondary control IC 102. The fifth switch circuit S5, the sixth switch circuit S6, and the seventh switch circuit S7 are off, and the eighth switch circuit S8 is on. As a result, the gate-source of the thirteenth switching element Q13 connected to the second signal output terminal OUT2 in the secondary side control IC 102 is short-circuited by the eighth switch circuit S8 being turned on, No charge is accumulated in the input capacitance Ciss of the thirteenth switching element Q13. That is, the thirteenth switching element Q13 functioning as a rectifying side synchronous rectifier is in an off state.

Note that the fourteenth switching element Q14 functioning as a commutation side synchronous rectifier operates in an on-state because it operates complementarily with the thirteenth switching element Q13 across a dead time.
[Operation at time t1]
FIG. 6 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 at time t1.

At time t1, the first switch circuit S1 in the primary side control IC 101 is turned on. Then, the current supplied from the first DC voltage unit Vdr1 flows through the first switch circuit S1, the primary winding Np2 of the pulse transformer PT, and the fourth switch circuit S4. When the primary winding Np2 of the pulse transformer PT is excited, a voltage is generated in the secondary winding Ns2 of the pulse transformer PT. Therefore, in the secondary side control IC 102, this is converted into the fifth switch circuit S5 and the sixth switch circuit S5. Is detected at the winding voltage detection terminal Vdet located at the connection point of the switch circuit S6.
[Operation in time interval t1 to t2]
FIG. 7 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the time interval t1 to t2.

The digital control unit in the secondary side control IC 102 turns on the fifth switch circuit S5 in response to the voltage input to the winding voltage detection terminal Vdet. By this operation, also in the secondary side control IC 102, the current supplied from the second DC voltage unit Vdr2 causes the fifth switch circuit S5, the secondary winding Ns2 of the pulse transformer PT, and the eighth switch circuit S8. Flowing through.
[Operation at time t2]
FIG. 8 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 at time t2.

At time t2, the digital control unit in the primary side control IC 101 turns off the fourth switch circuit S4, and the digital control unit in the secondary side control IC 102 turns off the eighth switch circuit S8. By this operation, in the primary side control IC 101, the current supplied from the first DC voltage unit Vdr1 flows into the input capacitor Ciss of the eleventh switching element Q11 and charges are charged, and the eleventh switching element Q11 turns on. At the same time, in the secondary control IC 102, the current supplied from the second DC voltage unit Vdr2 flows into the input capacitance Ciss of the thirteenth switching element Q13 and charges are charged, and the thirteenth switching element Q13 is turned on. To do.
[Operations during time t2 to t3]
FIG. 9 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the period from time t2 to t3.

When the turn-on of the eleventh switching element Q11 and the thirteenth switching element Q13 ends at time t2 to t3, the current supplied from the first DC voltage unit Vdr1 in the primary side control IC 101 is the first switch It returns to the first DC voltage unit Vdr1 via the circuit S1, the primary winding Np2 of the pulse transformer PT, and the third diode D3. Similarly, in the secondary side control IC 102, the current supplied from the second DC voltage unit Vdr2 is supplied to the fifth switch circuit S5, the secondary winding Ns2 of the pulse transformer PT, and the seventh diode D7. Through.
[Operations during time t3 to t4]
FIG. 10 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the period from time t3 to t4.

At time t3, the first switch circuit S1 is turned off in the primary side control IC 101, and the fifth switch circuit S5 is turned off in the secondary side control IC 102. With this operation, the current flowing through the primary winding Np2 and the secondary winding Ns2 of the pulse transformer PT is decreased during the time t3 to t4, while the second diode D2 and the pulse transformer PT are reduced in the primary control IC 101. In the secondary side control IC 102, it flows through the sixth diode D6, the secondary winding Ns2 of the pulse transformer PT, and the seventh diode D7. The electromagnetic energy accumulated in the pulse transformer PT1 is regenerated.
[Operations during time t4 to t5]
FIG. 11 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the period from time t4 to t5.

After that, at time t4, the current flowing through the primary winding Np2 and the secondary winding Ns2 of the pulse transformer PT approaches zero, and the second diode D2 and the third diode D3 in the primary side control IC 101, 2 When forward current stops flowing to each of the sixth diode D6 and the seventh diode D7 in the secondary control IC 102, the third switch circuit S3 in the primary control IC 101 and the seventh switch in the secondary control IC 102 Each switch circuit S7 is turned on. By this operation, the gate potentials of the eleventh switching element Q11 and the thirteenth switching element Q13 are maintained at the voltage value supplied from the second DC voltage unit Vdr2 (= first DC voltage unit Vdr1). Thus, the ON state is always maintained.
[Operation at time t5]
FIG. 12 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 at time t5.

At time t5, the sixth switch circuit S6 in the secondary side control IC 102 is turned on. Then, the current supplied from the first DC voltage unit Vdr1 flows through the seventh switch circuit S7, the secondary winding Ns2 of the pulse transformer PT, and the sixth switch circuit S6. When the secondary winding Ns2 of the pulse transformer PT is excited, a voltage is generated in the primary winding Np2 of the pulse transformer PT. Therefore, in the primary side control IC 101, this voltage is applied to the first switch circuit S1 and the second switch circuit S1. Is detected at a winding voltage detection terminal Vdet located at the connection point of the switch circuit S2.
[Operations during time t5 to t6]
FIG. 13 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the time interval t5 to t6.

  The digital control unit in the primary side control IC 101 turns on the second switch circuit S2 in response to the voltage input to the winding voltage detection terminal Vdet. With this operation, also in the primary side control IC 101, the current supplied from the second DC voltage unit Vdr2 causes the third switch circuit S3, the primary winding Np2 of the pulse transformer PT, and the second switch circuit S2. Flowing through.

In the middle of this period, the ninth switch circuit S9 and the tenth switch circuit S10 are also turned on. The amount of electromagnetic energy stored in the pulse transformer PT can be changed by adjusting the time length of the period from t5 to t6. Therefore, the drive voltage applied to the digital control units in the primary side control IC 101 and the secondary side control IC 102 can be controlled by controlling the time length of the period from t5 to t6.
[Operation at time t6]
FIG. 14 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 at time t6.
At time t6, the digital control unit in the primary side control IC 101 turns off the third switch circuit S3, and the digital control unit in the secondary side control IC 102 turns off the seventh switch circuit S7. By this operation, the charge accumulated in the input capacitance Ciss of the eleventh switching element Q11 is discharged in the primary side control IC 101, and the eleventh switching element Q11 is turned off. At the same time, in the secondary side control IC, the electric charge accumulated in the input capacitor Ciss of the thirteenth switching element Q13 is discharged, and the thirteenth switching element Q13 is turned off.
[Operation during time t6 to t7]
FIG. 15 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the period from time t6 to t7.

When the gate-source voltages of the eleventh switching element Q11 and the thirteenth switching element Q13 reach 0 V from time t6 to t7, the fourth diode D4 and 1 of the pulse transformer PT are set in the primary control IC 101. A current flows toward GND via the next winding Np2 and the second switch circuit S2. Similarly, in the secondary side control IC 102, a current flows toward the GND via the eighth diode D8, the secondary winding Ns2 of the pulse transformer PT, and the sixth switch circuit S6.
[Operation during time t7 to t8]
FIG. 16 shows a simplified circuit block diagram in the primary side control IC 101 and the secondary side control IC 102 in the period from time t7 to t8.
At time t7, the fourth switch circuit S4 in the primary side control IC 101 and the eighth switch circuit S8 in the secondary side control IC 102 are turned on, and at the same time, the second switch circuit S2 and the sixth switch circuit are turned on. S6 turns off. With this operation, the currents flowing in the primary winding Np2 and the secondary winding Ns2 of the pulse transformer PT are decreased between the times t7 and t8, respectively, while the fourth diode D4 and the pulse transformer PT in the primary side control IC 101. The secondary winding Np2 and the ninth diode D9 are charged to charge the seventh capacitor C7. In the secondary control IC 102, the eighth diode D8, the secondary winding Ns2 of the pulse transformer PT, It flows so as to charge the eighth capacitor C8 through the tenth diode D10.

Through the above-described operation, the driving energy of the eleventh switching element Q11 and the thirteenth switching element Q13 can be regenerated as electric power for driving the digital control circuits of the primary side control IC 101 and the secondary side control IC 102. If the ninth switch circuit S9 and the tenth switch circuit S10 are turned off during this period, the energy for charging the seventh capacitor C7 and the eighth capacitor C8 can be limited. Thereafter, the electromagnetic energy of the pulse transformer PT that has not yet been regenerated at the time of turn-off of the ninth switch circuit S9 and the tenth switch circuit S10 passes through the first diode D1 and the fifth diode D5 to the first DC voltage. Regenerated in the part Vdr1. This method can also be controlled to stabilize the voltage at the drive power supply terminal Vlogic of the digital control unit to the target value.
[Operation after time t8]
The operation in the section from the time t8 to the time t1 is the same as the above-mentioned [Operation in the section from time t0 to t1].

  Through the above-described operation, a signal indicating the timing immediately before turning on the eleventh switching element Q11 corresponding to the primary main switch output from the primary side control IC is transmitted via the pulse transformer PT to the secondary side. And is used as a timing signal for turning on the thirteenth switching element Q13 corresponding to the rectifier side synchronous rectifier in the secondary side synchronous rectifier circuit and output from the secondary side control IC The commutation side synchronous rectifier in the synchronous rectifier circuit is turned off. The commutation side synchronous rectifier is turned off at a timing immediately before the main switch is turned on, thereby preventing a through current from being generated due to simultaneous turning on of the main switch and the commutation side synchronous rectifier. A signal indicating the timing immediately before turning off the thirteenth switching element Q13 corresponding to the rectifying side synchronous rectifier is transmitted to the primary side via the pulse transformer PT, and the eleventh switching corresponding to the primary side main switch. It can be used as a timing signal for turning off the element Q11. Contrary to the above example, a signal indicating the timing immediately before the main switch is turned on can be transmitted from the secondary side to the primary side, and a signal indicating the timing immediately before the main switch is turned off is transmitted from the primary side. It can also be transmitted to the secondary side. Of the primary side and the secondary side, the signal transmitted first is preferentially executed. That is, complete bidirectional communication using one pulse transformer PT is possible. Furthermore, the regenerative energy can be used as a drive voltage source for the digital control unit in the control IC. That is, for example, the gate drive voltage of the eleventh switching element Q11, the twelfth switching element Q12, the thirteenth switching element Q13, and the fourteenth switching element Q14 is about 10 V, and the primary side control IC 101 and the secondary side control IC 101 When the drive voltage of the digital control unit of the side control IC 102 is about 1.8V, the voltage inductance of the pulse transformer PT is used as an energy storage element, so that any voltage as a switching regulator can be used instead of a step-down by a linear regulator. Can be generated, and the circuit efficiency can be increased. In addition, since the pulse transformer PT used for signal transmission between the primary and secondary is also used as an energy storage element, a simpler circuit configuration in which a switching regulator is separately configured.

  Note that the operations in the period from time t0 to t2 and in the period from time t4 to t6 are the period during which both the eleventh switching element Q11 and the twelfth switching element Q12 are off (dead time), and the thirteenth switching element Q13. And the 14th switching element Q14 are operations for creating a period (dead time) in which both are off. If a means for creating the dead time is provided separately, the third switch circuit S3 and the fourth switch circuit S4 are provided. The seventh switch circuit S7 and the eighth switch circuit S8 may always be turned off, that is, replaced with a simple diode.

The invention according to the first embodiment has the effects (a), (b), and (c) described above.
<< Second Embodiment >>
FIG. 17 shows the case where the second DC voltage unit Vdr2 is not connected to the drive voltage source and is connected to the ninth capacitor C9 in the primary side control IC 101 and the tenth capacitor C10 in the secondary side control IC 102. An internal block diagram of the primary side control IC 101 and the secondary side control IC 102 is shown. Taking the primary side control IC 101 as an example, if the ON time of the fourth switch circuit S4 is varied during the period in which the first switch circuit S1 is ON, the pulse from the first DC voltage unit Vdr1 It can be seen that the circuit composed of the excitation inductance of the transformer PT, the fourth switch circuit S4, the third switch circuit S3, and the ninth capacitor C9 is a step-up chopper type converter. That is, even when the voltage supplied from the first DC voltage unit Vdr1 is a DC voltage with a large fluctuation, the voltage is applied to the second signal output terminal OUT2 by controlling the ON time of the fourth switch circuit S4. The voltage value to be controlled can be controlled to be constant. Needless to say, this can also be applied to the secondary control IC 102.

The invention according to the second embodiment has the effects (a), (b), and (c) described above.
<When applied to non-isolated step-down converter>
FIG. 18 shows a circuit diagram according to an embodiment of a non-insulated step-down DC-DC converter using the control IC shown in FIG.

  A series circuit composed of a fifteenth switching element Q15 functioning as a power switching element and a sixteenth switching element Q16 functioning as a synchronous rectifier is connected to both ends of the DC input power source Vin. A DC voltage is output to the output terminal Vout from a connection point between the switching element Q15 and the sixteenth switching element Q16 through a smoothing circuit including the third inductor L3 and the sixteenth capacitor C16.

  The control IC 101 obtains a drive voltage from the first DC voltage unit Vdr1 and the second DC voltage unit Vdr2 and controls the fifteenth switching element Q15 to control the first signal output terminal OUT1 and the second signal. The primary winding of the pulse transformer PT is connected between the output terminal OUT2 and the secondary winding of the pulse transformer PT is the fourteenth diode D14, the fifteenth diode D15, the sixteenth diode D16, the sixth diode D16. The edge signal generated in the winding consisting of the resistor R6, the seventh resistor R7, the first Zener diode ZD1, the twelfth capacitor C12, the seventeenth switching element Q17 and the eighteenth switching element Q18 is converted into a square wave. Is connected to the control terminal of the fifteenth switching element Q15 via a circuit for performing the above. A thirteenth capacitor C13 is connected to the second signal output terminal OUT2. With this configuration, when the first switch circuit S1 and the fourth switch circuit S4 of the control IC 101 are in the on state and the second switch circuit S2 and the third switch circuit S3 are in the off state, a pulse is applied to the pulse transformer PT. By generating the signal, the fifteenth switching element Q15 can be turned on, the second switch circuit S2 and the third switch circuit S3 are in the on state, and the first switch circuit S1 and the fourth switch circuit S4. When is turned off, the fifteenth switching element Q15 can be turned off. That is, the pulse transformer PT can be used as a high side driver. Further, in order to control the sixteenth switching element Q16, the control terminal of the sixteenth switching element Q16 and the third signal output terminal OUT3 are connected, and the ground terminal GND is connected to the GND line.

  Further, the output voltage divided by the tenth resistor R10 and the eleventh resistor R11, the eighth resistor R8, the ninth resistor R9, the fourteenth capacitor C14, and the fifteenth capacitor C15 A combination of the ramp wave signal from the ramp wave forming circuit 104 is connected so as to be input to the feedback signal input terminal FB1, and this is the drive timing of the fifteenth switching element Q15 and the sixteenth switching element Q16. It plays the role of a feedback signal to decide.

The invention according to this embodiment has the effects (a) and (b) described above.
<When applied to non-insulated boost converter>
FIG. 19 shows a circuit diagram according to an embodiment of a non-insulated step-up DC-DC converter using the control IC shown in FIG.

  A series circuit including a fourth inductor L4 and a nineteenth switching element Q19 functioning as a power switch element is connected to both ends of the DC input power source Vin, and is synchronized with both ends of the nineteenth switching element Q19. A series circuit composed of a twentieth switching element Q20 functioning as a rectifier and a twentieth capacitor C20 is connected, and a DC voltage is output to the output terminal Vout using both ends of the twentieth capacitor C20 as outputs.

  The control IC 101 obtains a drive voltage from the first DC voltage unit Vdr1 and the second DC voltage unit Vdr2 and controls the nineteenth switching element Q19 in order to control the nineteenth switching element Q19. Are connected to the signal output terminal OUT3, and the ground terminal GND is connected to the GND line. Further, in order to control the twentieth switching element Q20, a primary winding of the pulse transformer PT is connected between the first signal output terminal OUT1 and the second signal output terminal OUT2, and the pulse transformer PT The secondary winding includes a seventeenth diode D17, an eighteenth diode D18, a nineteenth diode D19, a twelfth resistor R12, a thirteenth resistor R13, a second Zener diode ZD2, a nineteenth capacitor C19, The switching terminal Q21 and the 22nd switching element Q22 are connected to the control terminal of the twentieth switching element Q20 via a circuit for converting an edge signal generated in the winding into a square wave. The eighteenth capacitor C18 is connected to the second signal output terminal OUT2. With this configuration, when the first switch circuit S1 and the fourth switch circuit S4 of the control IC 101 are in the on state and the second switch circuit S2 and the third switch circuit S3 are in the off state, a pulse is applied to the pulse transformer PT. By generating the signal, the twentieth switching element Q20 can be turned on, the second switch circuit S2 and the third switch circuit S3 are in the on state, and the first switch circuit S1 and the fourth switch circuit S4. When is turned off, the twentieth switching element Q20 can be turned off. That is, the pulse transformer PT can be used as a high side driver.

  Although omitted in FIG. 19, a circuit that forms a ramp wave that increases when the nineteenth switching element Q19 is on and decreases when the nineteenth switching element Q19 is off is provided and input to the feedback signal terminal FB1. Is superimposed on the feedback signal.

The invention according to this embodiment has the effects (a) and (b) described above.
<< When applied to a non-insulated SEPIC converter >>
FIG. 20 shows a circuit diagram according to an embodiment of a non-insulated SEPIC (Single Ended Primary Inductance Converter) DC-DC converter using the control IC shown in FIG.

  A series circuit composed of a fifth inductor L5 and a twenty-third switching element Q23 functioning as a power switching element is connected to both ends of the DC input power source Vin, and a twenty-fourth switching element Q24 functioning as a synchronous rectifier A series circuit composed of a 22nd capacitor C22 and a sixth inductor L6 is connected to both ends of the 23rd switching element Q23, and is connected to both ends of the 6th inductor L6. On the other hand, a series circuit including a 24th switching element Q24 and a 25th capacitor C25 is connected, and a DC voltage is output to the output terminal Vout with both ends of the 25th capacitor C25 as outputs. Although the fifth inductor L5 and the sixth inductor L6 are illustrated as being magnetically coupled, they operate even if they are not magnetically coupled.

  The control IC 101 obtains a drive voltage from the first DC voltage unit Vdr1 and the second DC voltage unit Vdr2 and controls the 24th switching element Q24 to control the 24th switching element Q24 and the second signal output terminal OUT1 and the second signal. The primary winding of the pulse transformer PT is connected between the output terminal OUT2, and the secondary winding of the pulse transformer PT is the twentieth diode D20, the twenty-first diode D21, the twenty-second diode D22, and the sixteenth diode. The edge signal generated in the winding consisting of the resistor R16, the seventeenth resistor R17, the third Zener diode ZD3, the twenty-fourth capacitor C24, the twenty-fifth switching element Q25 and the twenty-sixth switching element Q26 is converted into a square wave. Is connected to the control terminal of the twenty-fourth switching element Q24 via a circuit for performing the above. The 23rd capacitor C23 is connected to the second signal output terminal OUT2. With this configuration, when the first switch circuit S1 and the fourth switch circuit S4 of the control IC 101 are in the on state and the second switch circuit S2 and the third switch circuit S3 are in the off state, a pulse is applied to the pulse transformer PT. By generating the signal, the 24th switching element Q24 can be turned on, the second switch circuit S2 and the third switch circuit S3 are in the on state, and the first switch circuit S1 and the fourth switch circuit S4. When is turned off, the 24th switching element Q24 can be turned off. That is, the pulse transformer PT can be used as a high side driver. Further, in order to control the 23rd switching element Q23, the control terminal of the 23rd switching element Q23 and the third signal output terminal OUT3 are connected, and the ground terminal GND is connected to the GND line.

  Although not shown in FIG. 20, a circuit that forms a ramp wave that increases when the 23rd switching element Q23 is in the on state and decreases when it is in the off state is provided and is input to the feedback signal terminal FB1. Is superimposed on the feedback signal.

  The invention according to this embodiment has the effects (a) and (b) described above.

101, 102 ... Control IC
103, 104: Ramp wave forming circuit L1: First inductor L2: Second inductor L3: Third inductor L4: Fourth inductor L5: Fifth inductor L6: Sixth inductor C1: First capacitor 2nd capacitor C3 ... 3rd capacitor C4 ... 4th capacitor C5 ... 5th capacitor C6 ... 6th capacitor C7 ... 7th capacitor C8 ... 8th capacitor C9 ... 9th capacitor C10 ... 10th capacitor C11 ... 11th capacitor C12 ... 12th capacitor C13 ... 13th capacitor C14 ... 14th capacitor C15 ... 15th capacitor C16 ... 16th capacitor C17 ... 17th capacitor C18 ... 18th Capacitor C19 ... 19th capacitor C20 ... 20th capacitor C21 ... 21st key Pacita C22 ... 22nd capacitor C23 ... 23rd capacitor C24 ... 24th capacitor C25 ... 25th capacitor Ciss ... gate-source capacitance D1 of switching element ... first diode D2 ... second diode D3 ... second 3rd diode D4 4th diode D5 5th diode D6 6th diode D7 7th diode D8 8th diode D9 9th diode D10 10th diode D11 11th Diode D12 ... 12th diode D13 ... 13th diode D14 ... 14th diode D15 ... 15th diode D16 ... 16th diode D17 ... 17th diode D18 ... 18th diode D19 ... 19th diode D20 ... 20th diode D21 ... 21st diode DoD22 ... 22nd diode ZD1 ... 1st Zener diode ZD2 ... 2nd Zener diode ZD3 ... 3rd Zener diode Q1 ... 1st switching element Q2 ... 2nd switching element Q3 ... 3rd switching element Q4 4th switching element Q5 5th switching element Q6 6th switching element Q7 7th switching element Q8 8th switching element Q9 9th switching element Q10 10th switching element Q11 11th switching element Q12 ... 12th switching element Q13 ... 13th switching element Q14 ... 14th switching element Q15 ... 15th switching element Q16 ... 16th switching element Q17 ... 17th switching element Q18 ... 18 switching elements Q DESCRIPTION OF SYMBOLS 19 ... 19th switching element Q20 ... 20th switching element Q21 ... 21st switching element Q22 ... 22nd switching element Q23 ... 23rd switching element Q24 ... 24th switching element Q25 ... 25th switching element Q26 ... 26th switching element S1 ... 1st switch circuit S2 ... 2nd switch circuit S3 ... 3rd switch circuit S4 ... 4th switch circuit S5 ... 5th switch circuit S6 ... 6th switch circuit S7 ... 7th switch circuit S8 ... 8th switch circuit S9 ... 9th switch circuit S10 ... 10th switch circuit R1 ... 1st resistor R2 ... 2nd resistor R3 ... 3rd resistor R4 ... 4th resistor 5th resistor R6 6th resistor R7 7th resistor R8 8th resistor R9 9th resistor R10 10th resistor R1 11th resistor R12 12th resistor R13 13th resistor R14 14th resistor R15 15th resistor R16 16th resistor R17 17th resistor R18 18th resistor R19 19 resistors T ... transformer PT ... pulse transformer Np1 ... first primary winding Np2 ... second primary winding Np3 ... third primary winding Ns1 ... first secondary winding Ns2 ... second Secondary winding Vin ... input voltage Vdet ... winding voltage detection terminal Vdr1 ... first DC voltage unit Vdr2 ... second DC voltage unit Vout ... output terminal Vref1 ... reference voltage OUT1 ... first output signal terminal OUT2 ... Second signal output terminal OUT3 ... Third signal output terminal FB1 ... Feedback signal input terminal COMP1 ... Comparator GND ... Ground terminal

Claims (4)

A first DC voltage unit to which a predetermined DC voltage is applied;
A second DC voltage section;
A GND terminal connected to a reference potential;
A first series circuit comprising a first switch circuit S1 and a second switch circuit S2,
A second series circuit comprising a third switch circuit S3 and a fourth switch circuit S4;
A controller for controlling on / off operations of the first to fourth switch circuits;
A first output terminal for leading out a connection point between the first switch circuit S1 and the second switch circuit S2, and a connection point between the third switch circuit S3 and the fourth switch circuit S4; A semiconductor integrated circuit including a second output terminal for leading out to the outside,
One end of the first series circuit is connected to the first DC voltage unit Vdr1,
One end of the second series circuit is connected to the second DC voltage unit Vdr2,
The other end of the first series circuit and the other end of the second series circuit are both connected to the GND terminal;
A reactance element is connected between the first output terminal and the second output terminal,
Winding voltage detecting means (Vdet) for detecting a change in voltage across the reactance element;
When at least the first switch circuit S1 is in an on state and both the second switch circuit S2 and the third switch circuit S3 are in an off state, a positive voltage is applied to the reactance element, or A negative voltage is applied to the reactance element when the second switch circuit (S2) is in an on state and both the first switch circuit (S1) and the fourth switch circuit (S4) are in an off state. Thus, an excitation current is passed through the reactance element to generate a pulse voltage, and the pulse voltage is transmitted to the outside as an edge signal. At least the first switch circuit S1 and the second switch circuit S2 are both when in the oFF state, a pulse voltage generated in the reactive element, by detecting by the winding voltage detecting means The semiconductor integrated circuit being characterized in that to be able to receive the edge signals from the outside. The semiconductor integrated circuit further includes a third output terminal that outputs a voltage input from the first DC voltage unit;
A sub-driver circuit for controlling whether or not to output a voltage to the third output terminal;
The turn-on and turn-off operations of the sub-driver circuit are controlled by the control unit,
The control unit is configured such that the square wave voltage generated at the second output terminal and the square wave voltage generated at the third output terminal are in a complementary relationship with each other across a period in which both are at a low level. The semiconductor integrated circuit according to claim 1, wherein the first to fourth switch circuits and the sub-driver circuit are controlled. An insulating switching power supply device in which the semiconductor integrated circuit according to claim 1 or 2 is used for a primary side control circuit and a secondary side control circuit, respectively.
DC power supply,
A transformer having at least one set of primary and secondary windings;
At least one power switch element for controlling whether or not to apply a DC voltage supplied from the DC power source to the primary winding;
Comprising at least a rectifier circuit including at least one synchronous rectifier is connected to the secondary winding, an output filter circuit for smoothing the output of the rectifier circuit, a,
At least primary and secondary windings, the primary side control the primary winding to the circuit, the secondary side control circuit to the secondary winding connected to the signal transmission transformer reactance element Use as
A pulse signal is transmitted bidirectionally between the semiconductor integrated circuit disposed on the primary side and the semiconductor integrated circuit disposed on the secondary side, and the drive timing of the power switch element and the synchronous rectifier is adjusted. An insulated switching power supply device characterized by controlling. The semiconductor integrated circuit according to claim 1 or 2 is used for a control circuit,
DC power supply,
At least one inductance element;
At least one power switch element for controlling whether or not to apply a DC voltage supplied from the DC power supply to the inductance element;
A rectifier circuit including at least one synchronous rectifier;
A non-insulated switching power supply device and an output filter circuit for smoothing the output of the rectifier circuit,
The power switch element or the synchronous rectifier is composed of a field effect transistor,
The source terminal of the field effect transistor is floating from the ground potential of the control circuit, and an edge signal to square wave signal conversion circuit is connected between the gate and source of the field effect transistor;
A non-insulated switching power supply device, wherein the field effect transistor is driven by a square wave signal obtained by converting an edge signal transmitted from the semiconductor integrated circuit through a transformer by the conversion circuit.