CN102208802B - Power switching tube overcurrent detection and overcurrent protection circuit - Google Patents
Power switching tube overcurrent detection and overcurrent protection circuit Download PDFInfo
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- CN102208802B CN102208802B CN2010102161211A CN201010216121A CN102208802B CN 102208802 B CN102208802 B CN 102208802B CN 2010102161211 A CN2010102161211 A CN 2010102161211A CN 201010216121 A CN201010216121 A CN 201010216121A CN 102208802 B CN102208802 B CN 102208802B
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Abstract
The invention provides a power switching tube overcurrent detection and overcurrent protection circuit, which comprises an overcurrent detection circuit and an overcurrent protection circuit. The overcurrent detection circuit comprises a sampling tube, a negative feedback circuit, a sampling resistor and a comparator, wherein the gate and source ends of the sampling tube are connected with the gate and source ends of a power switching tube to be detected; the negative feedback circuit can make the drain voltage of the sampling tube tend to be consistent with the drain voltage of the power switching tube; the sampling resistor is used for introducing current flowing through the sampling tube; and the comparator compares the voltage or current of the sampling resistor with an overcurrent reference voltage or current to judge whether the power switching tube has overcurrent or not to realize high-accuracy overcurrent detection. The overcurrent protection circuit comprises a latch used for receiving and latching a detected overcurrent signal, a power switching tube driving circuit and a mirror current tube circuit with a switch. When the switch is switched off, the mirror current tube circuit samples the current of the power switching tube driving circuit, and mirrors the sampled current into the current of the power switching tube to realize the overcurrent protection of the power switching tube.
Description
Technical field
The present invention relates to a kind of power switch pipe over-current detection and current foldback circuit.
Background technology
The turn-on and turn-off of power MOS pipe switch of utilizing switching amplifier, Switching Power Supply, charge pump realize the high efficiency conversion of signal and energy, have purposes more and more widely.This power MOS pipe switch has larger electric current to flow through usually when conducting, if electric current has surpassed the limit of bearing of this power MOS pipe switch, permanent damage may occur this power MOS pipe switch.Therefore, in order to guarantee the reliability of device, electric current that must convection current overpower metal-oxide-semiconductor switch carries out continuous detecting, and can protect the power MOS pipe switch when electric current is excessive.
About the detection of the electric current of convection current overpower metal-oxide-semiconductor switch, as shown in Figure 1, its core concept is proposed by US Patent No. 4553019 present the most widely used method.In Fig. 1, P type power MOS pipe switch 1 is connected with drain terminal 8 separately with the grid end 7 of sampling metal-oxide-semiconductor 2, and the source 10 of sampling metal-oxide-semiconductor 2 is R by a resistance value
S1Sampling resistor 3 be connected to power vd D, the source of power MOS pipe switch 1 is directly connected to supply voltage VDD.The dimension scale of power MOS pipe switch 1 and sampling metal-oxide-semiconductor 2 is N: 1.The common port 10 of sampling metal-oxide-semiconductor 2 and sampling resistor 3 is linked the negative input of a comparator 6, and current value is I
REF1Current source 5 be R with resistance value
REF1The common port 11 of resistance 4 on produce reference voltage V
REF1, this voltage is added to the positive input of comparator 6.When the electric current that flows through power MOS pipe switch 1 hour, the electric current that flows through sampling metal-oxide-semiconductor 2 is also less, the voltage V of comparator 6 negative inputs
S1Voltage V higher than positive input
REF1, so comparator 6 output low levels.When the electric current that flows through power MOS pipe switch 1 was higher, the electric current that flows through sampling metal-oxide-semiconductor 2 was also higher, causes V
S1Descend; Voltage V when comparator 6 negative inputs
S1Voltage V lower than positive input
REF1The time, comparator 6 output high level, expression power MOS pipe switch generation overcurrent.The shortcoming of this implementation method is, owing to there being sampling resistor 3, make the source voltage terminal of power MOS pipe switch 1 and sampling metal-oxide-semiconductor 2 inconsistent, cause flowing through the electric current and the non-linear relation of electric current that flows through power MOS pipe switch 1 of sampling metal-oxide-semiconductor 2, so it not real equal proportion sampling electric current; Sampling be actually voltage on power MOS pipe switch 1 drain terminal 8, and this voltage and reference voltage V
REF1Relatively, estimate by metal-oxide-semiconductor linear zone current formula the electric current that flows through power MOS pipe switch 1.US Patent No. 5670227 has been set forth above-mentioned principle.The problem of bringing like this is, R
REF1And I
REF1The accuracy of the deviation of absolute value, the process deviation of metal-oxide-semiconductor and metal-oxide-semiconductor linear zone current formula all can be brought sizable detection error of the electric current of convection current overpower metal-oxide-semiconductor switch.The most important thing is the voltage V that detects
S1With the electric current that flows through power MOS pipe switch 1 be not linear relationship, therefore can't be with program to V
S1Thereby revise the mistake flow point of accurate adjustment power MOS pipe switch 1.Same problem is present in US Patent No. 6479975 and US7403365.Excessive detection error can cause the being difficult to assurance in design,, if set over-current detection point too low, can cause the too early protection than heavy load the time, meeting automatic shutdown during as the larger volume of audio frequency amplifier output; If with over-current detection point set too high, can cause again protection to be lost efficacy, cause device failure.Therefore, power MOS pipe switch over-current protective device need to possess the more over-current detecting method of high accuracy, higher controllability reliably.
About the power MOS pipe switch being detected the safeguard measure after overcurrent, usually adopt the method for switch-off power metal-oxide-semiconductor switch, the large electric current that flows through the power MOS pipe switch is disappeared immediately.This method has reasonable protection effect for faults such as short circuits, but unfavorable for contingent instantaneous overload situation in system.When instantaneous overload occurred, of short duration over-current signal will trigger protection mechanism, and rupturing duty metal-oxide-semiconductor switch, quit work system.Whether a kind of improved method is that to add self-resetting devices, its principle be again to open the power MOS pipe switch after the time delay certain hour, detect overcurrent condition and disappear.Yet even added from recovery ways, still there is the state of interrupt output in power MOS pipe, and the guard method meeting of this rigidity has a strong impact on the normal operation of some systems that continuity is had relatively high expectations.
Summary of the invention
The object of the present invention is to provide a kind of high-precision power switch pipe over-current detection and current foldback circuit.
Reach in order to achieve the above object other purposes, power switch pipe over-current detection provided by the invention and current foldback circuit comprise: over-current detection circuit and the current foldback circuit that is connected to described over-current detection circuit output.
Over-current detection circuit comprises: grid, source respectively with the grid of power switch pipe to be detected, the sampling pipe that source is connected; The negative-feedback circuit that comprises amplifier, wherein, the drain terminal of described sampling pipe and power switch pipe to be detected is connected to two inputs of described amplifier, feeds back to described sampling pipe after the two drain terminal voltage differences amplifications that are used for access so that the drain terminal voltage of the drain terminal voltage of described sampling pipe and described power switch pipe to be detected reaches unanimity; Be used for the sampling resistor of incoming stream through the electric current of described sampling pipe; And with described sampling resistor, be connected, in order to the overcurrent reference voltage of the voltage of described sampling resistor or electric current and access or electric current are compared in order to judge the whether comparator of overcurrent of described power switch pipe to be detected;
Better, described sampling resistor can be the numerical digit adjustable resistance; Thus, the power switch pipe over-current detection circuit also can comprise that one is connected with described numerical digit adjustable resistance and is used for the Programmable Logic Controller of regulating resistance.
Current foldback circuit comprises: be connected to the over-current detection circuit output and be used for receiving and latching the latch of the over-current signal that detects; The power switch tube drives circuit that comprises current source, its Enable Pin with the power switch pipe of power switch pipe to be detected and described detection is connected, be used for the control signal according to described Enable Pin access, with one, determine that electric current carries out charge or discharge to the grid end of described power switch pipe to be detected; And the image current pipe circuit of belt switch; wherein; described switch is connected to the output of described latch; in order to according to the control signal of described latch output, open and close; and when described switch is closed; definite electric current of the described power switch tube drives circuit of described image current pipe circuit sampling, and mirror image becomes the electric current flow through described power switch pipe to be detected, to realize the current-limiting protection to described power switch pipe to be detected.
Better, when power switch pipe was P type metal-oxide-semiconductor, described latch comprised: the first inverter, the reset terminal of the signal inversion of described Enable Pin access are connected to described the first inverter output, input end of clock and the output of described comparator is connected, signal input part connects high level d type flip flop and with the second inverter of the anti-phase rear control signal as described switch of d type flip flop output signal.
Better, described power switch tube drives circuit comprises: the first current source and the second current source that electric current is determined, be subjected to described Enable Pin access signal controlling so that described the first current source to the first controlled switch of the grid end charging of described power switch pipe to be detected and be subjected to the signal controlling of described Enable Pin access so that second controlled switch of the grid end of described power switch pipe to be detected by described the second current source discharge.
In sum; power switch pipe over-current detection of the present invention and current foldback circuit reach unanimity the drain terminal voltage of sampling pipe and the drain terminal voltage of power switch pipe by negative-feedback technology; can improve the precision of over-current detection thus; and when overcurrent being detected; adopt image current to carry out current limliting to power tube, can effectively realize overcurrent protection.
Description of drawings
Fig. 1 is the circuit diagram of over-current detection circuit of the P type power MOS pipe switch of prior art.
Fig. 2 is the circuit diagram of P type power switch pipe over-current detection of the present invention and current foldback circuit.
Fig. 3 is the circuit theory diagrams of P type power switch pipe over-current detection circuit of the present invention.
Fig. 4 is the circuit diagram of P type power switch pipe over-current detection circuit of the present invention.
Fig. 5 is the circuit diagram of P type power switch pipe current foldback circuit of the present invention.
Fig. 6 is the circuit diagram of N-type power switch pipe over-current detection of the present invention and current foldback circuit.
Embodiment
Below with reference to accompanying drawing, power switch pipe over-current detection of the present invention and current foldback circuit are described in detail.
Embodiment one: in the present embodiment, and power switch pipe P type metal-oxide-semiconductor.
See also Fig. 2, power switch pipe over-current detection of the present invention and current foldback circuit comprise at least: over-current detection circuit and the current foldback circuit that is connected to described over-current detection circuit output.
As shown in Figure 3, it is the schematic diagram of described over-current detection circuit.The grid end 25 of sampling metal-oxide-semiconductor 14 is connected with source with the grid end of P type power MOS pipe switch 13 respectively with source (VDD).The drain terminal 28 of the drain terminal 27 of power MOS pipe switch 13 and sampling metal-oxide-semiconductor 14 is connected respectively to two inputs of amplifier 18.The output of amplifier 18 feeds back to the drain terminal 28 of sampling metal-oxide-semiconductor 14 by negative feedback control device 19, degenerative " empty short " effect can make the drain terminal voltage of the drain terminal voltage of sampling metal-oxide-semiconductor 14 and power MOS pipe switch 13 near consistent.This moment due to three terminal voltages of sampling metal-oxide-semiconductor 14 and power MOS pipe switch 13 all near consistent, can draw according to the linear zone current formula of metal-oxide-semiconductor: the electric current that flows through sampling metal-oxide-semiconductor 14 is linear with the electric current that flows through power MOS pipe switch 13, and their ratio is close to the ratio (in the drawings be made as 1/N) of sampling metal-oxide-semiconductor 14 with the size of power MOS pipe switch 13.Flow through the electric current I of sampling metal-oxide-semiconductor 14
S2The inflow resistance value is R
S2Sampling resistor 21, and to form size on sampling resistor 21 be I
S2* R
S2Voltage V
S2.Current value is I
REF2Current source 23 be R with resistance value
REF2Resistance 22 to form sizes be I
REF2* R
REF2Voltage V
REF2.These two voltages are two inputs 30 and 31 of input comparators 24 respectively.Produce the over-current detection signal on the output 32 of comparator 24.When the electric current I that flows through sampling metal-oxide-semiconductor 14
S2Greater than I
REF2* R
REF2/ R
S2The time, the level on the output 32 of comparator 24 overturns, and shows overcurrent occurs, and the electric current that flow through power MOS pipe switch 13 this moment is N*I
REF2* R
REF2/ R
S2.Can find out by following formula, the mistake flow point electric current of power MOS pipe switch 13 and the absolute value of resistance are irrelevant, therefore resistance R on integrated circuit diagram
REF2And R
S2Coupling when good, can set and cross very accurately flow point.Simultaneously, because the voltage V that detects
S2With the electric current that flows through power MOS pipe switch 13 be linear relationship, therefore can be with program to V
S2Thereby revise the mistake flow point of accurate adjustment power MOS pipe switch 13.For the ease of realizing, sampling resistor 21 can be arranged to the numerical digit adjustable resistance, use Programmable Logic Controller 20222 by the resistance value R of program to sampling resistor 21
S2Carry out the digitlization adjustment, thereby the mistake flow point of power MOS pipe switch 13 is carried out the digitlization adjustment.
Have numerous embodiments can realize the negative feedback control device that adopts in technique scheme, with reach make the sampling drain terminal voltage of metal-oxide-semiconductor and power MOS pipe switch drain terminal voltage near consistent purpose.Fig. 4 has provided the physical circuit of the negative feedback control device that adopts in the overcurrent detecting device technical scheme able to programme of the preferred P type of a kind of the present invention power MOS pipe switch.With reference to shown in Figure 4, the drain terminal of P type power MOS pipe switch 13 is connected to the positive input 27 of amplifier 18.The reverse input end 28 of amplifier 18 is connected with the drain terminal of P type sampling metal-oxide-semiconductor 14.The output 29 of amplifier 18 is linked the grid end of P type metal-oxide-semiconductor 19.In embodiment shown in Figure 4, P type metal-oxide-semiconductor 19 is as the negative feedback control device, and its source feeds back to the reverse input end 28 of amplifier 18.The drain terminal 30 of P type metal-oxide-semiconductor 19 is linked an end of sampling resistor 21, makes the electric current that flows through sampling metal-oxide-semiconductor 14 all flow into sampling resistor 21 by P type metal-oxide-semiconductor 19.Suppose that voltage on the positive input 27 of amplifier 18 is higher than the voltage on reverse input end 28, and the multiplication factor of amplifier 18 is enough large, the voltage on the output 29 of amplifier 18 uprises, the electric current that flows through P type metal-oxide-semiconductor 19 is diminished, thereby the voltage on the reverse input end 28 of amplifier 18 is raise until near the voltage on positive input 27.Suppose that voltage on the reverse input end 28 of amplifier 18 is higher than the voltage on positive input 27, and the multiplication factor of amplifier 18 is enough large, the voltage decreases on the output 29 of amplifier 18, make the electric current that flows through P type metal-oxide-semiconductor 19 become large, thereby make lower voltage on the reverse input end 28 of amplifier 18 until near the voltage on positive input 27.Therefore, it is consistent that this negative feedback loop can make voltage and the voltage on reverse input end 28 on amplifier 18 positive inputs 27 level off to, thereby make the drain terminal voltage of sampling metal-oxide-semiconductor 14 and the drain terminal voltage of power MOS pipe switch 13 level off to consistent.
As shown in Figure 5, it is described current foldback circuit schematic diagram.Current value is I
PCurrent source 66 and 67 the common port grid end 25 of linking P type power MOS pipe switch 13.One end of current source 66 is linked power supply potential (VDD) by P type metal-oxide-semiconductor 56.One end of current source 67 links ground by N-type metal-oxide-semiconductor 57.The Enable Pin 55 of P type power MOS pipe switch is linked respectively metal-oxide-semiconductor 56 and 57 grid ends.66,67,56, the 57 common P type power MOS pipe switch driving circuits that form.When Enable Pin 55 input high level of P type power MOS pipe switch, 56 cut-offs of P type metal-oxide-semiconductor, 57 conductings of N-type metal-oxide-semiconductor, current source 67 gives grid end 25 discharges of P type power MOS pipe switch 13 until earth potential, thereby makes 13 conductings of P type power MOS pipe switch.When Enable Pin 55 input low level of P type power MOS pipe switch, 56 conductings of P type metal-oxide-semiconductor, 57 cut-offs of N-type metal-oxide-semiconductor, current source 66 gives grid end 25 chargings of P type power MOS pipe switch 13 until power supply potential, thereby makes 13 cut-offs of P type power MOS pipe switch.The Enable Pin 55 of P type power MOS pipe switch is linked (Reset) end 59 that resets of d type flip flop (as latch) 60 by reverser 58.The over-current signal that the clock of d type flip flop 60 (Clk) end 32 receives from over-current detection circuit.The data of d type flip flop 60 (D) end 61 is connected to power supply potential.When high level occurring on the reset terminal 59 of d type flip flop 60, output low level on the output of d type flip flop 60 (Q) end 61.Low level occurs on the reset terminal 59 of d type flip flop 60, and while rising edge occurring on the clock end 32 of d type flip flop 60, export high level on the output 62 of d type flip flop 60; Low level occurs on the reset terminal 59 of d type flip flop 60, and while rising edge not occurring on the clock end 32 of d type flip flop 60, the Level hold on the output 62 of d type flip flop 60 is constant.The grid end of P type image current pipe 65 is connected with drain terminal, and with the grid end 25 of P type power MOS pipe switch 13, is connected.One end of P type metal-oxide-semiconductor 64 is connected with the source of P type image current pipe 65, and the other end is connected with power supply potential.The output 62 of d type flip flop 60 is linked the grid end 63 of P type metal-oxide-semiconductor 64 by reverser.When Enable Pin 55 input low level of P type power MOS pipe switch, 13 cut-offs of P type power MOS pipe switch, on the reset terminal 59 of d type flip flop 60, high level appears at this moment, output low level on the output 62 of d type flip flop 60, be high level thereby make on P type metal-oxide-semiconductor 64 grid ends 63,64 cut-offs of P type metal-oxide-semiconductor, so P type image current pipe 65 is not had an effect.To sum up, when 13 cut-off of P type power MOS pipe switch, P type image current pipe 65 is not had an effect.When Enable Pin 55 input high level of P type power MOS pipe switch, 13 conductings of P type power MOS pipe switch, this moment d type flip flop 60 reset terminal 59 on low level appears.When overcurrent occurs, on the clock end 32 of d type flip flop 60, rising edge appears, export high level on the output 62 of d type flip flop 60, make on P type metal-oxide-semiconductor 64 grid ends 63 and become low level, 64 conductings of P type metal-oxide-semiconductor, thereby the electric current I P that makes current source 67 flows through P type image current pipe 65, has limited the further decline of voltage on the grid end 25 of P type power MOS pipe switch 13, thereby has limited the further increase of the electric current that flows through P type power MOS pipe switch 13.According to the image current relation, the electric current that flows through P type power MOS pipe switch 13 with the ratio of the electric current that flows through P type image current pipe 65 close to the ratio (in the drawings be made as M/1) of P type power MOS pipe switch 13 with the size of P type image current pipe 65.To sum up, when 13 conducting of P type power MOS pipe switch, in case overcurrent detected, the electric current that flows through P type power MOS pipe switch 13 can be limited in M*I all the time
P, until Enable Pin 55 input low levels of P type power MOS pipe switch reset d type flip flop 60.
Embodiment two:
The present embodiment and embodiment one difference are that power switch pipe is the N-type metal-oxide-semiconductor.
As shown in Figure 6, power switch pipe over-current detection and current foldback circuit comprise: over-current detection circuit and the current foldback circuit that is connected to described over-current detection circuit output.
Wherein, over-current detection circuit comprises: sampling pipe 35, negative-feedback circuit, sampling resistor 42 and comparator 45.The grid of sampling pipe 35, source are connected with grid, the source of power switch pipe 34 respectively; Negative-feedback circuit comprises amplifier 39 and negative feedback control device (being the N-type metal-oxide-semiconductor) 40, the drain terminal of described sampling pipe 35 and power switch pipe 34 is connected to the input 48 and 47 of described amplifier 39, and the end that drain terminal connection, drain terminal and the sampling resistor that output, source and the sampling pipe of the grid end connection amplifier 39 of N-type metal-oxide-semiconductor 40 is connected is connected connects; The other end of sampling resistor 42 connects power vd D, and its resistance is R
s3, it can be also the numerical digit adjustable resistance, by Programmable Logic Controller 202, controls its resistance; The inverting input 40 of comparator 45 is connected connection with sampling resistor, the common port 51 that normal phase input end is connected to reference resistance 43 and current source 44 is connected with described sampling resistor.
Current foldback circuit comprises: the image current pipe circuit of latch, power switch tube drives circuit and belt switch.Described latch is d type flip flop 75, and the reset terminal 74 of d type flip flop 75 is connected to that the Enable Pin 69 of power switch pipe, input end of clock Clk are connected with the output 52 of described comparator 45, signal input part 76 connects high level (being VDD); Grid termination Enable Pin 69, the drain terminal of P type metal-oxide-semiconductor 70 in the power switch tube drives circuit (i.e. the first controlled switch) connects power supply, source and current source and is connected connection; The other end 53 of current source 72 connects the grid end 53 of power switch pipe; One end of current source 73 connects the grid end 53 of power switch pipe, and the other end connects the drain terminal of N-type metal-oxide-semiconductor 71 (i.e. the second controlled switchs); The grid end of N-type metal-oxide-semiconductor 71 connects Enable Pin 69, source ground connection (being GND); Output 77, source ground connection, the drain terminal of the grid termination d type flip flop 75 of the switch 78 in the image current pipe circuit of belt switch connects the source of N-type image current pipe 79; The drain terminal of N-type image current pipe 79, grid end all are connected with the common gate end 53 that sampling pipe 35 is connected with power switch pipe.
The operation principle of foregoing circuit and embodiment one are similar, therefore be not described in detail in this.
In sum; power switch pipe over-current detection of the present invention and current foldback circuit reach unanimity the drain terminal voltage of sampling pipe and the drain terminal voltage of power switch pipe by negative-feedback technology; can realize the high accuracy of over-current detection thus; and detecting over-current state simultaneously; limit the electric current that flows through power switch pipe by image current, can realize thus the overcurrent protection to power switch pipe.
Above-described embodiment just lists expressivity explanation principle of the present invention and effect, but not is used for restriction the present invention.Any person skilled in the art person all can without departing from the spirit and scope of the present invention, modify to above-described embodiment.Therefore, the scope of the present invention, should be as listed in claims.
Claims (11)
1. a power switch pipe over-current detection and current foldback circuit is characterized in that comprising: over-current detection circuit and be connected to the current foldback circuit of described over-current detection circuit output, wherein,
Described over-current detection circuit comprises:
Grid, source respectively with the grid of power switch pipe to be detected, the sampling pipe that source is connected;
The negative-feedback circuit that comprises amplifier, the drain terminal of described sampling pipe and power switch pipe to be detected is connected to two inputs of described amplifier, feeds back to described sampling pipe after the two drain terminal voltage differences amplifications that are used for access so that the drain terminal voltage of the drain terminal voltage of described sampling pipe and described power switch pipe to be detected reaches unanimity;
Sampling resistor, be used for the electric current of incoming stream through described sampling pipe; With
Comparator, be connected with described sampling resistor, in order to the overcurrent reference voltage of the voltage of described sampling resistor or electric current and access or electric current are compared in order to judge whether overcurrent of described power switch pipe to be detected;
Described current foldback circuit comprises:
Latch, be connected to the output of described comparator, is used for receiving and latching the over-current signal that detects;
The power switch tube drives circuit that comprises current source, be connected with the Enable Pin of the power switch pipe of described power switch pipe to be detected and described detection, be used for the control signal according to described Enable Pin access, with one, determine that electric current carries out charge or discharge to the grid end of described power switch pipe to be detected; With
The image current pipe circuit of belt switch; described switch is connected to the output of described latch; in order to according to the control signal of described latch output, open and close; and when described switch is closed; definite electric current of the described power switch tube drives circuit of described image current pipe circuit sampling; and mirror image becomes the electric current flow through described power switch pipe to be detected, to realize the current-limiting protection to described power switch pipe to be detected.
2. power switch pipe over-current detection as claimed in claim 1 and current foldback circuit, it is characterized in that: described sampling resistor is the numerical digit adjustable resistance.
3. power switch pipe over-current detection as claimed in claim 2 and current foldback circuit characterized by further comprising: be connected with described numerical digit adjustable resistance and be used for the Programmable Logic Controller of regulating resistance.
4. power switch pipe over-current detection as claimed in claim 1 and current foldback circuit; it is characterized in that: when power switch pipe was P type metal-oxide-semiconductor, described latch comprised: the first inverter, the reset terminal of the signal inversion of described Enable Pin access are connected to described the first inverter output, input end of clock and the output of described comparator is connected, signal input part connects high level d type flip flop and with the second inverter of the anti-phase rear control signal as described switch of d type flip flop output signal.
5. power switch pipe over-current detection as claimed in claim 1 and current foldback circuit, it is characterized in that: described power switch tube drives circuit comprises: the first current source and the second current source that electric current is determined, be subjected to described Enable Pin access signal controlling so that described the first current source to the first controlled switch of the grid end charging of described power switch pipe to be detected and be subjected to the signal controlling of described Enable Pin access so that second controlled switch of the grid end of described power switch pipe to be detected by described the second current source discharge.
6. power switch pipe over-current detection circuit is characterized in that comprising:
Grid, source respectively with the grid of power switch pipe to be detected, the sampling pipe that source is connected;
The negative-feedback circuit that comprises amplifier, the drain terminal of described sampling pipe and power switch pipe to be detected is connected to two inputs of described amplifier, feeds back to described sampling pipe after the two drain terminal voltage differences amplifications that are used for access so that the drain terminal voltage of the drain terminal voltage of described sampling pipe and described power switch pipe to be detected reaches unanimity;
Sampling resistor, be used for the electric current of incoming stream through described sampling pipe; With
Comparator, be connected with described sampling resistor, in order to the overcurrent reference voltage of the voltage of described sampling resistor or electric current and access or electric current are compared in order to judge whether overcurrent of described power switch pipe to be detected.
7. power switch pipe over-current detection circuit as claimed in claim 6, it is characterized in that: described sampling resistor is the numerical digit adjustable resistance.
8. power switch pipe over-current detection circuit as claimed in claim 7 characterized by further comprising: be connected with described numerical digit adjustable resistance and be used for the Programmable Logic Controller of regulating resistance.
9. power switch pipe current foldback circuit is characterized in that comprising:
Latch, be connected to the output of the over-current detection circuit of power switch pipe to be detected, is used for receiving and latching the over-current signal that detects;
The power switch tube drives circuit that comprises current source, be connected with the Enable Pin of the power switch pipe of described power switch pipe to be detected and described detection, be used for the control signal according to described Enable Pin access, with one, determine that electric current carries out charge or discharge to the grid end of described power switch pipe to be detected; With
The image current pipe circuit of belt switch; described switch is connected to the output of described latch; in order to according to the control signal of described latch output, open and close; and when described switch is closed; definite electric current of the described power switch tube drives circuit of described image current pipe circuit sampling; and mirror image becomes the electric current flow through described power switch pipe to be detected, to realize the current-limiting protection to described power switch pipe to be detected.
10. power switch pipe current foldback circuit as claimed in claim 9; it is characterized in that: when power switch pipe was P type metal-oxide-semiconductor, described latch comprised: the first inverter, the reset terminal of the signal inversion of described Enable Pin access are connected to described the first inverter output, input end of clock and the output of comparator is connected, signal input part connects high level d type flip flop and with the second inverter of the anti-phase rear control signal as described switch of d type flip flop output signal.
11. power switch pipe current foldback circuit as claimed in claim 9 is characterized in that: described power switch tube drives circuit comprises: the first current source and the second current source that electric current is determined, be subjected to described Enable Pin access signal controlling so that described the first current source to the first controlled switch of the grid end charging of described power switch pipe to be detected and be subjected to the signal controlling of described Enable Pin access so that second controlled switch of the grid end of described power switch pipe to be detected by described the second current source discharge.
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| CN2010102161211A CN102208802B (en) | 2010-06-29 | 2010-06-29 | Power switching tube overcurrent detection and overcurrent protection circuit |
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| CN2010102161211A CN102208802B (en) | 2010-06-29 | 2010-06-29 | Power switching tube overcurrent detection and overcurrent protection circuit |
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| CN102208802B true CN102208802B (en) | 2013-11-13 |
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| TW201232218A (en) * | 2011-01-28 | 2012-08-01 | Infinno Technology Corp | Automatic adjusting protection and detection circuit for power supply |
| CN103515922A (en) * | 2012-06-25 | 2014-01-15 | 中国人民解放军理工大学 | Self-recovery and overcurrent protection circuit for power amplifier integrated circuit |
| CN103575964B (en) | 2012-07-19 | 2016-03-23 | 快捷半导体(苏州)有限公司 | A kind of over-current detection circuit of power switch pipe and method |
| CN102801294B (en) * | 2012-07-27 | 2016-05-11 | 北京市科通电子继电器总厂 | A kind of sampling current foldback circuit in parallel |
| CN102832599B (en) * | 2012-08-24 | 2014-07-30 | 电子科技大学 | Over-current protection circuit |
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