CN107346945B - Switching power unit and semiconductor device - Google Patents

Switching power unit and semiconductor device Download PDF

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Publication number
CN107346945B
CN107346945B CN201610298154.2A CN201610298154A CN107346945B CN 107346945 B CN107346945 B CN 107346945B CN 201610298154 A CN201610298154 A CN 201610298154A CN 107346945 B CN107346945 B CN 107346945B
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China
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circuit
winding
voltage
feedback signal
output
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CN201610298154.2A
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Chinese (zh)
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CN107346945A (en
Inventor
忠政由道
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三垦电气株式会社
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Abstract

The present invention provides switching power unit and semiconductor device.Switching power unit includes transformer, with first winding, secondary winding and auxiliary winding;Switch element is connected in series with the first winding;Output circuit is transmitted to the electric power of the secondary winding according to the switch motion with the switch element from the first winding, generates power supply output;Feedback signal generative circuit, the auxiliary winding voltage that the auxiliary winding induction generates during according to the secondary side conducting for flowing through the secondary winding in electric current, generates feedback signal during secondary side conducting;And control circuit, the switch element is driven according to the feedback signal, wherein the control circuit includes voltage detecting circuit, determines whether the auxiliary winding voltage is more than threshold value during electric current flows through the secondary side conducting of the secondary winding;And halt circuit stops switch motion according to the signal of the voltage detecting circuit.

Description

Switching power unit and semiconductor device

Technical field

The present invention relates to switching power units.

Background technique

In the switching power unit that input side and outlet side are electrically insulated using transformer, it is known to one-time detection The switching power unit of (PSR:Primary-Side Regulated) mode is provided with induction in the primary side of transformer and produces The auxiliary winding of the raw voltage proportional to the voltage generated in the secondary winding of transformer, and feel according in auxiliary winding The voltage that should be generated controls output voltage (such as US8125799B2, US2010/0134182A1).

The switching power unit that above patent document is recorded is with following such circuit: circuit detection is loaded with from light Or the output voltage decline that non-loaded load sudden change is associated, voltage reduction signal is output to secondary winding.Switch electricity Source device according to the voltage reduction signal for being transmitted to auxiliary winding since secondary winding switch motion, inhibit and load sudden change phase The output voltage of companion declines.

Output voltage is controlled according to the voltage for incuding generation in auxiliary winding for what above patent document was recorded One-time detection mode switching power unit for, when have occurred auxiliary winding broken string or by transformer lead pin failure welding When the failure that the connection of the auxiliary winding Deng caused by disconnects, due to not for detecting the unit of output voltage, so as to cause defeated Overvoltage out causes secondary side smoothing capacity device to damage or load damage.

In the switching power unit that above patent document is recorded, filled although being able to suppress with the associated power supply of load sudden change The variation in voltage that the output end set generates, but can not inhibit/stop the output voltage because of caused by the open circuit of auxiliary winding to rise.

In addition, there is also following such Considerations: the switching power unit of one-time detection mode is to be envisioned for not making With the cheap and small-sized product of photoelectrical coupler, it is difficult the additional excess voltage protection for having used photoelectrical coupler.

Summary of the invention

One embodiment of the present invention is to complete in view of the foregoing, even if its purpose is to provide one kind auxiliary windings Open circuit can also carry out overvoltage protection, switch with excess voltage protection in the case where not using photoelectrical coupler Power supply device.

Switching power unit of the invention includes transformer, with first winding, secondary winding and auxiliary winding; Switch element is connected in series with the first winding;Output circuit, according to the switch motion with the switch element It is transmitted to the electric power of the secondary winding from the first winding, generates power supply output;Feedback signal generative circuit, basis exist The secondary side that electric current flows through the secondary winding auxiliary winding voltage that the auxiliary winding induction generates during being connected, at this Secondary side generates feedback signal during being connected;And control circuit, the switch element is driven according to the feedback signal, Wherein, the control circuit includes voltage detecting circuit, determines that the phase is connected in the secondary side that the secondary winding is flowed through in electric current Whether the interior auxiliary winding voltage is more than threshold value;And halt circuit makes according to the signal of the voltage detecting circuit Switch motion stops.

According to one method of the present invention, even if auxiliary winding broken string or auxiliary winding pin or voltage detection resistances occur Failure welding be also able to carry out the overvoltage protection of output voltage.

Detailed description of the invention

Fig. 1 is the block diagram for showing the structure for an example for illustrating the switching power unit of illustrative embodiment.

Fig. 2 is the block diagram of the control circuit of the switching power unit of Fig. 1.

Fig. 3 is the wave for showing the movement of each section of control circuit of Fig. 2 in the case where becoming open circuit from starting Shape figure.

Fig. 4 is the wave for showing the movement of each section of control circuit of Fig. 2 in the case where becoming open circuit from usual Shape figure.

Specific embodiment

Fig. 1 shows the structure for an example for illustrating the switching power unit of illustrative embodiment.

Switching power unit 1 shown in FIG. 1 include rectifier DB 1, transformer T1, switch element Q1, control circuit 2, Generate the output circuit 4 of power supply output and the feedback signal generative circuit 5 for making the output voltage stabilization of output circuit 4.

Power circuit 3 has rectification circuit DB 1, capacitor C1, C2 and reactor L1, the L2 being made of diode bridge, Power circuit 3 is smooth to rectify from the alternating current of AC power source AC input.

Transformer 1 is in primary side with first winding P1 and auxiliary winding P2 and in secondary side with secondary winding S1.One The polarity of secondary winding P1, be set to the polarity of secondary winding S1 and auxiliary winding P2 it is opposite each other.

First winding P1 is connect via switch element Q1 with power circuit 3.In addition, secondary winding S1 with have diode D5 It is connected with the output circuit 6 of capacitor C6.

With the switch motion of switch element Q1, electric power is transmitted to secondary side from the primary side of transformer T1, is sent to The electric power of secondary side rectify by the diode D5 and capacitor C6 of output circuit 4 smooth.As a result, by direct current be supplied to The load (not shown) that output circuit 4 connects.

Auxiliary winding P2 is connect with feedback signal generative circuit 5.Feedback signal generative circuit 5 is according to switch element Q1 Switch motion and by auxiliary winding P2 induction generate voltage, generate feedback signal.

Also, in the example in the figures, capacitor C3 is connect via diode D2 with auxiliary winding P2, and capacitor C3 is just Extreme son is connect with the power voltage input terminal VCC of control circuit 2.The voltage that auxiliary winding P2 induction generates is by diode D2 It carries out rectifying VCC terminal that is smooth and being supplied to control circuit 2 with capacitor C3, is used as the control of drive control circuit 2 Circuit supply voltage.

Fig. 2 shows the structures of control circuit 2.

The voltage that control circuit 2 will enter into VCC terminal works as supply voltage, and control switch element Q1's opens Pass acts the output voltage stabilization to make output circuit 4.

Control circuit 2 includes excess voltage protection OVP, the oscillating circuit of start-up circuit STARTUP, VCC terminal voltage PWMOSC, driving circuit DRV, lead-edge-blanking circuit LEB, overcurrent protection circuit OCP, sampling keep (S/H) circuit Sampling 1, error amplifier OTA and feedback control comparator CP.

Switch element Q1 is the power MOSFET of N-type in the example in the figures.The drain electrode of switch element Q1 is with transformer T's The source electrode of first winding P1 connection, switch element Q1 is connect via resistance R3 with the negative terminal of capacitor C2.

Start-up circuit STARTUP be arranged in the control circuit 2 being connected with the positive terminal of capacitor C2 ST terminal and with Between the VCC terminal of the connected control circuit 2 of the positive terminal of capacitor C3.Start-up circuit STARTUP is constant-current circuit, Switch control start before starting when work, to be connected to VCC terminal capacitor C3 supply constant current.

Protect circuit PROTECTION according to the overvoltage detection circuit OVP of the VCC terminal from control circuit 2 and after The signal for the auxiliary winding voltage detection circuit 20 stated stops the movement of driving circuit DRV and keeps halted state.

Oscillating circuit PWMOSC exports the clock signal for switch element Q1 to be connected with the fixed cycle.From oscillating circuit The clock signal of PWMOSC output is input into the set terminal S of flip-flop circuit, then via 2 OR circuit OR1, OR3 quilts It is input to driving circuit DRV.

Driving circuit DRV is connect with the grid of switch element Q1.Driving circuit DRV turns the output signal of OR circuit OR3 It is changed to the voltage signal for being enough the grid of control switch element Q1, generates the driving signal for being used for driving switch element Q1.

Resistance R3 is the current sense resistor for detecting the drain current for flowing through switch element Q1, the source of switch element Q1 Tie point between pole and resistance R3 is connected to the OCP terminal of control circuit 2.

Lead-edge-blanking circuit LEB makes to carry out in the drain current detection signal of the self-resistance 3, production in switch element Q1 conducting Invalidating signal (blanking) in a period of raw surge voltage.Drain current detect signal via lead-edge-blanking circuit LEB and via Overcurrent sensing circuit OCP and OR circuit OR2 is input into the reseting terminal R of flip-flop circuit.

Overcurrent sensing circuit OCP detects signal to drain current and overcurrent detection threshold value voltage is compared, and is leaking When electrode current detection signal, i.e. resistance R3 reaches overcurrent detection threshold value voltage relative to the voltage drop of GND terminal voltage, output Cut-off signals.The cut-off signals are input into the reseting terminal R of flip-flop circuit via OR circuit OR2, and switch element Q1 is closed It is disconnected.

S/H circuit Sampling 1 is anti-to the feedback terminal FB's for being input to control circuit 2 from feedback signal generative circuit 5 Feedback signal is detected, and keeps voltage of the output signal of OR circuit OR1 as H level (high level) at the time of.By S/H electricity The voltage that road Sampling 1 is kept is input into the reversed input terminal of error amplifier OTA.Also, in S/H circuit At the time of Sampling 1 becomes next H level of OR circuit OR1, the feedback signal that is kept by S/H circuit Sampling 1 It is updated.

In-phase input terminal the applied reference voltage Vr1, error amplifier OTA of error amplifier OTA is to by S/H electricity Difference between the voltage that road Sampling 1 is maintained on capacitor Cfb and reference voltage Vr1 amplifies, and generates error amplification Signal.The error amplification signal is input into the reverse side of feedback control comparator CP via level shifting circuit LEVELSHIFT Son.

The feedback phase correction end of feedback control comparator CP and the control circuit 2 for being connected with phasing electricity container C5 Sub- COMP is connected.Also, feedback control comparator CP is to the error amplification signal after phasing and via lead-edge-blanking electricity The drain current detection signal of road LEB input is compared, when drain current detection signal is greater than error amplification signal, output Cut-off signals.The cut-off signals are input into the reseting terminal R of trigger via OR circuit.Switch element Q1 is turned off as a result,.

Feedback control comparator CP is according to the error amplification signal after drain current detection signal and phasing to switch The conducting amplitude of element Q1 is controlled, and the output voltage for controlling it as output circuit 4 is lower, error amplification signal is bigger, It is longer that amplitude is then connected.The output voltage of output circuit 4 is stablized as a result,.

Auxiliary winding voltage detection circuit 20 includes One shot (one shot) circuit 205, comparator 206, reference voltage Vr2, AND circuit 201,204, counter 202 and timer circuit 203.

Timer 2 03 is several mS grades of oscillators, and clock signal is output to the terminal and meter of AND circuit 201 The clock input terminal CK of number device 202.The output terminal Q of counter 202 is connected with another terminal of AND circuit 201, The output of AND circuit 201 is output to protection circuit PROTECTION.

In addition, counter 202 is the counter of 2 bits.The output of the reseting terminal R and AND circuit 204 of counter 202 Terminal is connected.

The non-inverting terminal of comparator 206 is connected with the FB terminal of control circuit 2, and reference voltage is connected on inverting terminal Vr2.Reference voltage Vr2 is set to the voltage lower than reference voltage Vr1.(Vr2 < < Vr1)

It is higher than benchmark electricity in the feedback signal for being input to the feedback terminal FB of control circuit 2 from feedback signal generative circuit 5 In the case where pressing Vr2, H level is output to a terminal of AND circuit 204 by comparator 206.

One shot circuit 205 is connect with the output of OR circuit OR1, becomes H level in the output signal of OR circuit OR1 At the moment, single-tap is signaled another terminal for being output to AND circuit 204.

The feedback signal from feedback signal generative circuit 5 be higher than reference voltage Vr2 in the case where, AND circuit 204 with Single-tap from One shot circuit 205 signals to carry out " with operation (AND) ", and H level signal is output to counter 202 Reseting terminal R, therefore, counter 202 is reset, and L level (low level) signal is output to another of AND circuit 201 Terminal.It as a result, will not be from auxiliary winding voltage detection circuit 20 to protection circuit PROTECTION output signal.

On the other hand, in the case where the feedback signal from feedback signal generative circuit 5 is lower than reference voltage Vr2, by L Level signal is output to the reseting terminal R of counter 202, therefore, even if signaling with the single-tap from One shot circuit 205 It carries out " with operation ", counter 202 is not also reset, and H level signal is output to another terminal of AND circuit 201.By This stops the movement of driving circuit DRV from auxiliary winding voltage detection circuit 20 to protection circuit PROTECTION output signal Only and keep halted state.

Hereinafter, movement when being opened a way based on terminal A or B of the Fig. 3 and Fig. 4 to auxiliary winding P2 is illustrated.

Fig. 3 is the control electricity of terminal A or B as Fig. 2 in the case where open circuit for showing the auxiliary winding P2 from starting The waveform diagram of the movement of each section on road 2.

In moment t0, AC power source AC is connected, the VCC terminal voltage of control circuit 2 is made via start-up circuit STARTUP Rise, in moment t1, control circuit 2 starts, and starts to carry out switch motion.At this point, at due to the terminal A or B of auxiliary winding P2 In open circuit, therefore feedback signal is not input into FB terminal, and FB terminal voltage is the low-voltage less than reference voltage Vr2, COMP Terminal voltage rises.

Also, it is exported in moment t1, timer circuit Timer using H level signal as clock, in moment t2, letter Number reversion.

In addition, in the terminal A or B of not auxiliary winding P2 open circuit but in the case where open circuit between resistance R4 and R5, instead Feedback signal is not input into FB terminal similarly, and FB terminal voltage is the low-voltage less than reference voltage Vr2, COMP terminal voltage Rise.

From moment t2 to moment t3, timer circuit 203 is exported using L level signal as clock, and output voltage reaches To overvoltage and sustained over voltage condition.

Then, in moment t3, timer circuit 203 is exported using H level signal as clock.

In moment t3, since the feedback signal from feedback signal generative circuit 5 is lower than reference voltage Vr2, ratio L level signal is output to a terminal of AND circuit 204 compared with device 206.AND circuit 204 is output into L level as a result, And L level signal is output to the reseting terminal R of counter 202, therefore, counter 202 is not reset, and by H level signal It is output to another terminal of AND circuit 201.H level signal is output to protection circuit by AND circuit 201 as a result, PROTECTION stops the movement of driving circuit DRV and keeps halted state.

Fig. 4 is the control electricity of terminal A or B as Fig. 2 in the case where open circuit for showing the auxiliary winding P2 from usual The waveform diagram of the movement of each section on road 2.

It is normally carried out work before reaching moment t5, in moment t5, above-mentioned open-circuit fault occurs.At this point, due to auxiliary The terminal A or B of winding P2 is helped to be in open circuit, therefore normal feedback signal is not input into FB terminal, FB terminal voltage reduces For the low-voltage less than reference voltage Vr2, COMP terminal voltage rises as a result,.

In addition, in the terminal A or B of not auxiliary winding P2 open circuit but in the case where open circuit between resistance R4 and R5, just Normal feedback signal is not input into FB terminal similarly, and FB terminal voltage is the low-voltage less than reference voltage Vr2, the end COMP Sub- voltage rises.

Also, in moment t5, timer circuit 203 is exported using H level signal as clock, in moment t7, signal Reversion.The input terminal CK of counter 202 timer circuit 203 clock signal from the L level at the time of progress that becomes H level It counts.Therefore, in moment t5, without counting, until next moment t8, the output of counter 202 keeps L level.

In moment t8, FB terminal voltage is less than the value of reference voltage Vr2, and therefore, L level is output to by comparator 206 One terminal of AND circuit 204 inputs L level signal from S/H circuit (Sampling 2) 205 to another terminal.At the moment T8, when from 203 input clock of timer circuit, the reseting terminal of counter 202 is in L level, and therefore, counter 202 is by H electricity Ordinary mail number is input to another terminal of AND circuit 201.

H level signal is output to protection circuit PROTECTION by AND circuit 201 as a result, makes moving for driving circuit DRV Make to stop and keeps halted state.

Also, i.e. moment t5~t8 during the output of counter 202 is transferred to L level and maintains L level from H level In a period of, it is in overvoltage condition.This is because consider output voltage on startup rise to until burning voltage when Between.That is, stopping the detection during FB terminal voltage decline when starting within the clock cycle of timer circuit 203.Change speech It, the clock cycle of timer circuit 203 is preferably set to during output voltage on startup reaches burning voltage FB voltage becomes the more than time of reference voltage Vr2 or more.

As described above, according to this switching power unit 1, in the control circuit of the switching power unit of one-time detection mode With auxiliary winding voltage detection circuit, even if the failure that normal feedback signal is not input to control circuit has occurred as a result, Also overvoltage protection can reliably be carried out.

In addition, since control circuit has auxiliary winding voltage detection circuit, because being based on photoelectric coupling without additional The excess voltage protection of device.

Claims (2)

1. a kind of switching power unit comprising:
Transformer, with first winding, secondary winding and auxiliary winding;
Switch element is connected in series with the first winding;
Output circuit, according to the switch element switch motion and from the first winding be transmitted to it is described it is secondary around The electric power of group generates power supply output;
Feedback signal generative circuit, according to electric current flow through the secondary winding secondary side conducting during it is described auxiliary around The auxiliary winding voltage that group induction generates generates feedback signal during secondary side conducting;And
Control circuit drives the switch element according to the feedback signal,
Wherein, the control circuit includes
Voltage detecting circuit determines to flow through the secondary winding in electric current by comparing the feedback signal and reference voltage Secondary side conducting during the auxiliary winding voltage whether be more than threshold value, the feedback signal be lower than the reference voltage When to halt circuit output signal;And
The halt circuit stops switch motion according to the signal of the voltage detecting circuit.
2. a kind of semiconductor device, which is characterized in that
The semiconductor device is constituted are as follows: the control circuit comprising switching power unit described in claim 1.
CN201610298154.2A 2016-05-06 2016-05-06 Switching power unit and semiconductor device CN107346945B (en)

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Application Number Priority Date Filing Date Title
CN201610298154.2A CN107346945B (en) 2016-05-06 2016-05-06 Switching power unit and semiconductor device

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Application Number Priority Date Filing Date Title
CN201610298154.2A CN107346945B (en) 2016-05-06 2016-05-06 Switching power unit and semiconductor device

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CN107346945A CN107346945A (en) 2017-11-14
CN107346945B true CN107346945B (en) 2019-08-09

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202385330U (en) * 2011-09-06 2012-08-15 上海新进半导体制造有限公司 LED driving circuit
CN203537225U (en) * 2013-09-18 2014-04-09 江门市三通科技实业有限公司 Novel antisurge constant-current switching power supply
CN104602390A (en) * 2014-01-14 2015-05-06 深圳市稳先微电子有限公司 Dual-winding single-stage primary feedback LED (Light Emitting Diode) lamp drive circuit
CN204567528U (en) * 2015-04-03 2015-08-19 帝发技术(无锡)有限公司 North America version parking heating device power supply
CN104852589A (en) * 2014-02-13 2015-08-19 英飞凌科技奥地利有限公司 Switched mode power supply circuit

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8125799B2 (en) * 2009-10-23 2012-02-28 Bcd Semiconductor Manufacturing Limited Control circuits and methods for switching mode power supplies

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN202385330U (en) * 2011-09-06 2012-08-15 上海新进半导体制造有限公司 LED driving circuit
CN203537225U (en) * 2013-09-18 2014-04-09 江门市三通科技实业有限公司 Novel antisurge constant-current switching power supply
CN104602390A (en) * 2014-01-14 2015-05-06 深圳市稳先微电子有限公司 Dual-winding single-stage primary feedback LED (Light Emitting Diode) lamp drive circuit
CN104852589A (en) * 2014-02-13 2015-08-19 英飞凌科技奥地利有限公司 Switched mode power supply circuit
CN204567528U (en) * 2015-04-03 2015-08-19 帝发技术(无锡)有限公司 North America version parking heating device power supply

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