CN205753362U - A kind of overcurrent protection for Switching Power Supply translation circuit compensates system - Google Patents

Abstract

The utility model discloses a kind of overcurrent protection for Switching Power Supply translation circuit and compensate system, including current detection module, the current detection module switching current I to Switching Power Supply translation circuit_ONDetect, the electric current I of current detection module output afterwards_CSTo the input of overcurrent protection comparator, linear compensation module output current I_CPTo the input of overcurrent protection comparator, reference current I_REFAlso entering into the input of overcurrent protection comparator, overcurrent protection comparator is by I_CS+I_CPWith I_REFCompare, if I_CS+I_CP>I_REFThen overcurrent protection comparator produces overcurrent protection signal and overcurrent protection signal is delivered to lead-edge-blanking module carries out lead-edge-blanking; to produce final overcurrent protection signal and to deliver to Logic control module, Logic control module controls the drive circuit in Switching Power Supply translation circuit and disconnects.Linear compensation module of the present utility model can adjust over-current protection point with supply voltage and the situation of change of temperature.

Description

A kind of overcurrent protection for Switching Power Supply translation circuit compensates system

Technical field

This utility model relates to current foldback circuit field, particularly relates to a kind of mistake for Switching Power Supply translation circuit Stream protection compensation system.

Background technology

DC-DC converter, outside belt current the most certain in addition to design needs to meet performance requirement and ability with voltage, from The protective measure of body is the most extremely important.Such as overcurrent protection, overvoltage protection, overheat protector etc..At present DC-DC has high frequency to open The high-power MOS FET switch closing characteristic has been in control extensive application, but its ability bearing short-time overload is more weak.At load electricity Road system occurs abnormal, such as zero load, or the most heavily loaded in the case of the power consumption that produces can be increased dramatically, thus affect switch mosfet The normal work of pipe, and MOSFET may be burnt out.Power circuit can cut out by current foldback circuit in the short time, it is ensured that circuit system Unite without damage.

In traditional Over Current Protection System, compared with reference current by the electric current of detection switch MOSFET and produced stream Protection signal, but do not take into account the switch conducting resistance of MOSFET and conducting resistance with voltage and the change of temperature, thus make Become over-current protection point bigger with the drift of supply voltage and temperature, it is possible under certain conditions, over-current protection point is too high, device Part power density is excessive, adds the risk of switch permanent damage.

Utility model content

Utility model purpose: the purpose of this utility model be to provide one can effectively reduce over-current protection point with voltage and The overcurrent protection for Switching Power Supply translation circuit of the drift degree of temperature compensates system.

Technical scheme: for reaching this purpose, this utility model by the following technical solutions:

Overcurrent protection for Switching Power Supply translation circuit described in the utility model compensates system, including current detecting mould Block, the current detection module switching current I to Switching Power Supply translation circuit_ONDetect, the electricity of current detection module output afterwards Stream I_CSTo the input of overcurrent protection comparator, linear compensation module output current I_CPTo the input of overcurrent protection comparator, Reference current I_REFAlso entering into the input of overcurrent protection comparator, overcurrent protection comparator is by I_CS+I_CPWith I_REFCompare Relatively, if I_CS+I_CP>I_REF, then overcurrent protection comparator produces preliminary overcurrent protection signal and is passed to lead-edge-blanking mould Block carries out lead-edge-blanking, and to produce final overcurrent protection signal and to deliver to Logic control module, Logic control module controls to open Close the drive circuit in power converting circuit to disconnect.

Further, described current detection module includes the first current source IS1 and the second current source IS2, also includes the first electricity Stream mirror and the second current mirror, the first current mirror includes the first N-channel technotron M1 and the second N-channel technotron M2, the second current mirror includes the first P-channel technotron M4 and the second P-channel technotron M5, the first current source The outfan of IS1, the outfan of the second current source IS2 connect drain electrode and the 2nd N of the first N-channel technotron M1 respectively The drain electrode of channel junction field-effect pipe M2, the drain electrode of the second N-channel technotron M2 is also connected with the 3rd N-channel junction type field effect Should the grid of pipe M3, the drain electrode of the 3rd N-channel technotron M3 connects the drain electrode of the first P-channel technotron M4, The input of the first current source IS1, the input of the second current source IS2, the source electrode of the first P-channel technotron M4 and The source electrode of two P-channel technotron M5 is connected and the drain electrode of input voltage VDD, the second P-channel technotron M5 is made For the outfan of current detection module, the source electrode of the 3rd N-channel technotron M3 connects the first N-channel technotron The source electrode of M1, the source electrode of the first N-channel technotron M1 is also connected with one end of resistance R1, and the other end of resistance R1 connects the The drain electrode of four N-channel technotron MS1, the source ground of the 4th N-channel technotron MS1, the 4th N-channel junction type The source electrode of the gate input voltage VDD of field effect transistor MS1, the second N-channel technotron M2 connects one end of resistance R2, electricity One end of the other end connecting valve S1 of resistance R2 and one end of switch S2, the other end ground connection of switch S2, the other end of switch S1 Connect the drain electrode of the 5th N-channel technotron M0, the source ground of the 5th N-channel technotron M0, the 5th N-channel The grid of technotron M0 connects control switch, whether controls on-off control to the 5th N-channel technotron M0's Gate input voltage, the switching current I of input switch power converting circuit is gone back in the drain electrode of the 5th N-channel technotron M0_ON。

Further, described linear compensation module includes that current mirror, current mirror include the first N-channel technotron MN1 Drain electrode with the second N-channel technotron MN2, the first N-channel technotron MN1 connects one end of resistance R4, electricity The other end of resistance R4 connects one end of resistance R3, the other end input voltage VDD of resistance R3, the second N-channel technotron The drain electrode of MN2 is as the outfan of linear compensation module.

Further, described overcurrent protection comparator includes the first current comparator IC1 and the second current comparator IC2, the The input input current I of one current comparator IC1_CP, electric current I_CSWith reference current I_REF, electric current I_CPWith electric current I_CSDirection phase With, reference current I_REFWith electric current I_CPIn opposite direction, the outfan of the first current comparator IC1 connects the second current comparator IC2 Input, the outfan of the second current comparator IC2 is as the outfan of overcurrent protection comparator.

Further, described overcurrent protection comparator includes voltage comparator VC1, the in-phase input end of voltage comparator VC1 Input current I_CPWith electric current I_CS, the in-phase input end of voltage comparator VC1 is also connected with one end of resistance R5, another of resistance R5 End ground connection, the inverting input input reference current I of voltage comparator VC1_REF, the inverting input of voltage comparator VC1 also connects One end of connecting resistance R6, the other end ground connection of resistance R6, the outfan of voltage comparator VC1 is defeated as overcurrent protection comparator Go out end.

Beneficial effect: the utility model discloses a kind of overcurrent protection for Switching Power Supply translation circuit and compensate system, Linear compensation module therein can adjust over-current protection point with supply voltage and the situation of change of temperature, thus effectively prevent When supply voltage is higher, over-current protection point is too high and occurs that big electric current causes switching tube permanent damage, the most also stabilizes Peak power output, so that switching tube is attained by peak power planarization in full voltage input range.

Accompanying drawing explanation

Fig. 1 is the circuit diagram of Switching Power Supply translation circuit of the present utility model；

Fig. 2 is system block diagram of the present utility model；

Fig. 3 is the circuit diagram of the current detection module of detailed description of the invention of the present utility model；

Fig. 4 is the circuit diagram of the linear compensation module of detailed description of the invention of the present utility model；

Fig. 5 is the circuit diagram of a kind of embodiment of the overcurrent protection comparator of detailed description of the invention of the present utility model；

Fig. 6 is the circuit diagram of the another kind of embodiment of the overcurrent protection comparator of detailed description of the invention of the present utility model；

Fig. 7 is the simulation result occurring overcurrent protection and overvoltage protection while detailed description of the invention of the present utility model Figure.

Detailed description of the invention

Below in conjunction with detailed description of the invention, the technical solution of the utility model is further introduced.

Switching Power Supply translation circuit is as it is shown in figure 1, the utility model discloses a kind of for Switching Power Supply translation circuit Overcurrent protection compensates system, as in figure 2 it is shown, include current detection module 1, overcurrent protection comparator 2, linear compensation module 3, front Along blanking module 4 and Logic control module 5.The current detection module 1 switching current I to Switching Power Supply translation circuit_ONExamine Surveying, current detection module 1 exports electric current I afterwards_CSTo the input of overcurrent protection comparator 2, linear compensation module 3 exports electric current I_CPTo the input of overcurrent protection comparator 2, reference current I_REFAlso enter into the input of overcurrent protection comparator 2, cross stream and protect Protect comparator 2 by I_CS+I_CPWith I_REFCompare, if I_CS+I_CP>I_REF, then overcurrent protection comparator 2 produces overcurrent protection letter Number and overcurrent protection signal delivered to lead-edge-blanking module 4 carry out lead-edge-blanking, to produce final overcurrent protection signal and to give To Logic control module 5, Logic control module 5 controls the drive circuit in Switching Power Supply translation circuit and disconnects.

Current detection module 1 is as it is shown on figure 3, include exporting the first equal current source IS1 of electric current and the second current source IS2, also includes the first current mirror 11 and the second current mirror 12, and the first current mirror 11 includes the first N-channel technotron M1 With the second N-channel technotron M2, the second current mirror 12 includes the first P-channel technotron M4 and the second P-channel Technotron M5, the outfan of the first current source IS1, the outfan of the second current source IS2 connect the first N-channel knot respectively The drain electrode of type field effect transistor M1 and the drain electrode of the second N-channel technotron M2, the leakage of the second N-channel technotron M2 Pole is also connected with the grid of the 3rd N-channel technotron M3, and the drain electrode of the 3rd N-channel technotron M3 connects a P The drain electrode of channel junction field-effect pipe M4, the input of the first current source IS1, the input of the second current source IS2, a P ditch The source electrode of road technotron M4 and the source electrode of the second P-channel technotron M5 are connected and input voltage VDD, the 2nd P The drain electrode of channel junction field-effect pipe M5 is as the outfan of current detection module 1, the source of the 3rd N-channel technotron M3 Pole connects the source electrode of the first N-channel technotron M1, and the source electrode of the first N-channel technotron M1 is also connected with resistance R1 One end, the other end of resistance R1 connects the drain electrode of the 4th N-channel technotron MS1, the 4th N-channel technotron The source ground of MS1, the gate input voltage VDD of the 4th N-channel technotron MS1, the second N-channel technotron The source electrode of M2 connects one end of resistance R2, one end of the other end connecting valve S1 of resistance R2 and one end of switch S2, switchs S2 Other end ground connection, switch S1 the other end connect the 5th N-channel technotron M0 drain electrode, the 5th N-channel junction type field The source ground of effect pipe M0, the grid of the 5th N-channel technotron M0 connects control switch, whether controls on-off control Gate input voltage to the 5th N-channel technotron M0, the drain electrode of the 5th N-channel technotron M0 also inputs out Close the switching current I of power converting circuit_ON。

As shown in Figure 4, including current mirror 31, current mirror 31 includes the first N-channel technotron to linear compensation module 3 The drain electrode of MN1 and the second N-channel technotron MN2, the first N-channel technotron MN1 connects one end of resistance R4, The other end of resistance R4 connects one end of resistance R3, the other end input voltage VDD of resistance R3, the second N-channel junction field The drain electrode of pipe MN2 is as the outfan of linear compensation module 3.

A kind of embodiment of overcurrent protection comparator 2 is as it is shown in figure 5, include the first current comparator IC1 and the second electric current The input input current I of comparator IC2, the first current comparator IC1_CP, electric current I_CSWith reference current I_REF, electric current I_CPWith electricity Stream I_CSDirection is identical, reference current I_REFWith electric current I_CPIn opposite direction, the outfan of the first current comparator IC1 connects the second electricity The input of stream comparator IC2, the outfan of the second current comparator IC2 is as the outfan of overcurrent protection comparator 2.

The another kind of embodiment of overcurrent protection comparator 2 as shown in Figure 6, including voltage comparator VC1, voltage comparator The in-phase input end input current I of VC1_CPWith electric current I_CS, the in-phase input end of voltage comparator VC1 is also connected with the one of resistance R5 End, the other end ground connection of resistance R5, the inverting input input reference current I of voltage comparator VC1_REF, voltage comparator VC1 Inverting input be also connected with one end of resistance R6, the other end ground connection of resistance R6, the outfan of voltage comparator VC1 is as mistake The outfan of stream protection comparator 2.

From the figure 3, it may be seen that switch S1 and switch S2 is used to control whether switching current I_ONCarry out detecting: as switch S1 When Guan Bi, switch S2 disconnect, to switching current I_ONDetect；When switching S1 disconnection, switch S2 Guan Bi, not to switching current I_ONDetect.From the figure 3, it may be seen that when conducting resistance=the 5th N-channel junction type field effect of the 4th N-channel technotron MS1 Should k times of conducting resistance of pipe M0, and during R1=R2=R, I_CSFor:

$Ics=\frac{rdson\×(Ion+Iq-Iq\×k)}{R+K\×rdson}---\left(1\right)$

In formula (1), rdson is the conducting resistance of the 5th N-channel technotron M0.

When overcurrent protection occurs, I_ONMeet:

Ion ＞ ＞ Iq × k (2)

Ion ＞ ＞ Iq (3)

Therefore, I_CSCan be reduced to:

$Ics=\frac{Ion}{K+\frac{R}{rdson}}=\frac{V_{OUT}\×I_{OUT}}{V_{IN}\×(K+\frac{R}{rdson})}---\left(4\right)$

I during overcurrent protection_REF、I_CPAnd I_CSMeet:

I_CS+I_CP>I_REF (5)

$I_{CP}=\frac{VDD-VGS}{R3+R4}=\frac{VDD-VGS}{R^{\′}}---\left(6\right)$

In formula (4), V_INBeing supply voltage for VDD, VDD, in formula (6), VGS is the first N-channel technotron MN1 Voltage between grid and source electrode, R '=R3+R4.

Formula (4) and formula (6) are substituted in formula (5) and obtain:

$I_{OUT}>\frac{V_{IN}\×(k+\frac{R}{rdson})\×(I_{REF}-\frac{VDD-VGS}{R^{\′}})}{V_{OUT}}---\left(7\right)$

Visible, by selecting suitable R ' over-current protection point can be made constant with the change of supply voltage or reduce.By formula (7) understand after derivation, by using resistance R3 and R4 of different temperature coefficients and adjusting the proportioning of R3 and R4, then can make stream Protection point raises with temperature and slightly reduces.

This utility model has an advantage that, i.e. the power density flatness of Switching Power Supply translation circuit have also been obtained and changes Kind.

P=1/2*I*I*rdson (8)

Not having the circuit that voltage linear compensates along with VIN rising, rdson reduction, but Ipeak raises, power increases；Add After voltage linear compensates circuit, VIN raises, and rdson reduces, and over-current protection point electric current can be made to reduce or constant, then power Reduce.

Additionally, this utility model has an advantage that, i.e. after zero load powers on or zero load is stable, for different output electricity Hold and inductance, it is possible to the situation of over-current over-voltage protection simultaneously occurs.

Fig. 7 is emulation schematic diagram.

After there is OV protection,

Toff=L*dI/ (VIN-VOUT) (9)

DelV=Q/C=1/2*I*toff/C=1/2*I*L*I/ [(VIN-VOU) * C] (10)

So along with VIN raises, if over-current protection point electric current also raises, then delV rises much higher when VIN=MAX, from And require that the resistance to of device is pressed with bigger surplus.And after adding voltage linear compensation, then VIN raises, IOC reduces, then delV is also Reduce, thus the surplus that device is pressure is also required that low spot.All above VIN is VDD.

Claims (5)

1. the overcurrent protection for Switching Power Supply translation circuit compensates system, it is characterised in that: include current detection module (1), the current detection module (1) the switching current I to Switching Power Supply translation circuit_ONDetect, afterwards current detection module (1) Output electric current I_CSTo the input of overcurrent protection comparator (2), linear compensation module (3) output electric current I_CPTo overcurrent protection ratio The input of relatively device (2), reference current I_REFAlso enter into the input of overcurrent protection comparator (2), overcurrent protection comparator (2) by I_CS+I_CPWith I_REFCompare, if I_CS+I_CP>I_REF, then overcurrent protection comparator (2) produces preliminary overcurrent protection Signal is also passed to lead-edge-blanking module (4) and carries out lead-edge-blanking, to produce final overcurrent protection signal and to deliver to logic Control module (5), Logic control module (5) controls the drive circuit in Switching Power Supply translation circuit and disconnects.

Overcurrent protection for Switching Power Supply translation circuit the most according to claim 1 compensates system, it is characterised in that: institute State current detection module (1) and include the first current source IS1 and the second current source IS2, also include the first current mirror (11) and second Current mirror (12), the first current mirror (11) includes the first N-channel technotron M1 and the second N-channel technotron M2, the second current mirror (12) includes the first P-channel technotron M4 and the second P-channel technotron M5, the first electricity The outfan of stream source IS1, the outfan of the second current source IS2 connect respectively the first N-channel technotron M1 drain electrode and The drain electrode of the second N-channel technotron M2, the drain electrode of the second N-channel technotron M2 is also connected with the 3rd N-channel knot The grid of type field effect transistor M3, the drain electrode of the 3rd N-channel technotron M3 connects the first P-channel technotron M4's Drain electrode, the input of the first current source IS1, the input of the second current source IS2, the source of the first P-channel technotron M4 Pole is connected with the source electrode of the second P-channel technotron M5 and input voltage VDD, the second P-channel technotron M5's Drain the outfan as current detection module (1), and the source electrode of the 3rd N-channel technotron M3 connects the first N-channel knot The source electrode of type field effect transistor M1, the source electrode of the first N-channel technotron M1 is also connected with one end of resistance R1, and resistance R1's is another The drain electrode of one end connection the 4th N-channel technotron MS1, the source ground of the 4th N-channel technotron MS1, the The source electrode of the gate input voltage VDD of four N-channel technotron MS1, the second N-channel technotron M2 connects resistance One end of R2, one end of the other end connecting valve S1 of resistance R2 and one end of switch S2, the other end ground connection of switch S2, switch The other end of S1 connects the drain electrode of the 5th N-channel technotron M0, and the source electrode of the 5th N-channel technotron M0 connects Ground, the grid of the 5th N-channel technotron M0 connects control switch, whether controls on-off control to the 5th N-channel junction type The gate input voltage of field effect transistor M0, input switch power converting circuit is gone back in the drain electrode of the 5th N-channel technotron M0 Switching current I_ON。

Overcurrent protection for Switching Power Supply translation circuit the most according to claim 1 compensates system, it is characterised in that: institute State linear compensation module (3) and include that current mirror (31), current mirror (31) include the first N-channel technotron MN1 and the 2nd N The drain electrode of channel junction field-effect pipe MN2, the first N-channel technotron MN1 connects one end of resistance R4, and resistance R4's is another One end connects one end of resistance R3, the other end input voltage VDD of resistance R3, the drain electrode of the second N-channel technotron MN2 Outfan as linear compensation module (3).

Overcurrent protection for Switching Power Supply translation circuit the most according to claim 1 compensates system, it is characterised in that: institute State overcurrent protection comparator (2) and include the first current comparator IC1 and the second current comparator IC2, the first current comparator IC1 Input input current I_CP, electric current I_CSWith reference current I_REF, electric current I_CPWith electric current I_CSDirection is identical, reference current I_REFWith Electric current I_CPIn opposite direction, the outfan of the first current comparator IC1 connects the input of the second current comparator IC2, the second electricity The outfan of stream comparator IC2 is as the outfan of overcurrent protection comparator (2).

Overcurrent protection for Switching Power Supply translation circuit the most according to claim 1 compensates system, it is characterised in that: institute State the in-phase input end input current I that overcurrent protection comparator (2) includes voltage comparator VC1, voltage comparator VC1_CPAnd electricity Stream I_CS, the in-phase input end of voltage comparator VC1 is also connected with one end of resistance R5, and the other end ground connection of resistance R5, voltage ratio is relatively The inverting input input reference current I of device VC1_REF, the inverting input of voltage comparator VC1 is also connected with one end of resistance R6, The other end ground connection of resistance R6, the outfan of voltage comparator VC1 is as the outfan of overcurrent protection comparator (2).