CN102810851A - Over-current protective circuit and digital output circuit - Google Patents
Over-current protective circuit and digital output circuit Download PDFInfo
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- CN102810851A CN102810851A CN2012102797014A CN201210279701A CN102810851A CN 102810851 A CN102810851 A CN 102810851A CN 2012102797014 A CN2012102797014 A CN 2012102797014A CN 201210279701 A CN201210279701 A CN 201210279701A CN 102810851 A CN102810851 A CN 102810851A
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Abstract
The invention provides an over-current protective circuit and a digital output circuit. The over-current protective circuit comprises a current limiting circuit, a timing circuit, a voltage regulating circuit and a comparator. When the digital output circuit is at an over-current status, the over-current protective circuit limits the current within a second threshold value by the over-current limiting circuit to determine the current at the over-current status, and outputs a first control signal by the comparator in the voltage regulating unit to control a switch tube to quickly switch off for closing the output, thereby ensuring the high switch-off speed at the over-current status without changing a fuse; when the switch-off time of the switch tube is longer than the first time timed by the timing unit, the voltage regulating unit outputs a second control signal to control the switch tube to switch on; and the switch-on time of the switch tube is the second time timed by the timing unit; and if the output is still at the over-current status, the output is closed again. According to the over-current protective circuit and the digital output circuit, the time for retuning output to normal is determined by repeatedly and periodically trying until the output is not at the over-current status.
Description
Technical field
The present invention relates to the digital output circuit field, relate in particular to a kind of current foldback circuit and digital output circuit.
Background technology
In digital output circuit, damage device in order to prevent overcurrent, generally be employed in the method for connect in the output circuit fusing fuse or resettable fuse.
When electric current flow through fuse, the resistance that fuse exists made the fuse heating, along with its caloric value of increase of time also increases.And the size of electric current and its resistance has confirmed to produce the speed of heat, and the structure of fuse and the situation of its installation have been confirmed the speed that heat dissipates, if the speed that produces heat is during less than the speed of heat dissipation, fuse can not fuse.Equal the speed that heat dissipates if produce the speed of heat, it can not fuse yet in considerable time.When having only the speed that dissipates greater than heat when the speed that produces heat, the heat of generation is more and more, when temperature be elevated to the fusing point of fuse when above fuse just can fuse, and the fuse that must more renew cause use inconvenient.Therefore series connection fusing fuse method is when actual overcurrent, because of its fusing speed slower, so have to the protection of load equipment shortcoming fast inadequately.
Resettable fuse is by forming through the polymer resin of special processing and the conducting particles that is distributed in the inside.When circuit was short-circuited or transship, the heat that the big electric current of the resettable fuse of flowing through produces melted polymer resin, and volume increases rapidly, forms high-impedance state, and operating current reduces rapidly, thereby circuit is limited and protects.After fault was got rid of, resettable fuse is crystallisation by cooling again, volume contraction, and conducting particles forms conductive path again, and resettable fuse reverts to low resistive state, thereby accomplishes the protection to circuit, need not artificially change.The operating principle of resettable fuse is a kind of dynamic equilibrium of energy, when the electric current that flows through the resettable fuse series of elements increases or ambient temperature raises, if but when reaching the balance of the heat of generation and the heat of distributing, resettable fuse series still is failure to actuate.Have only when electric current or ambient temperature improve again; The heat that produces makes resettable fuse series of elements temperature increase suddenly greater than the heat that distributes, and makes these elements be in the high resistant guard mode; The increase of impedance has limited electric current; Thereby protective circuit equipment is avoided damaging, if the heat that the enough resettable fuse series of elements of the heat that voltage produced that applies give out, just the resettable fuse series of elements that is under the variable condition can be in operate condition (high resistant) always.Have only when the loss of voltage that applies, resettable fuse series just can be recovered automatically.Connect the resettable fuse method when actual overcurrent, the size of current when being difficult to confirm overcurrent, and also the speed of disconnecting consumers equipment is slower, and quick inadequately to the protection of load equipment.And the big overcurrent to moment can't be protected.Though need not change fuse, be difficult to confirm from the recovery time of recovering insurance.
Summary of the invention
In view of this; The invention provides a kind of current foldback circuit and digital output circuit, with solve in the available circuit to the load equipment protection inadequately fast, use inconvenient, size of current when being difficult to confirm overcurrent and recover the problem that recovery time of insurance is difficult to confirm certainly.
To achieve these goals, the existing scheme that proposes is following:
A kind of current foldback circuit is applied to digital output circuit, comprising: current limliting unit, timing unit and voltage-regulation unit, wherein:
Said current limliting unit links to each other with power supply, switching tube and the said timing unit of said digital output circuit respectively; Said switching tube connects ground connection after the load; When said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Perhaps, said current limliting unit links to each other with ground, said switching tube and said timing unit respectively, and said switching tube connects power supply after connecing load, and when said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Said voltage-regulation unit links to each other with switching tube with said timing unit, current limliting unit respectively; When said source current during greater than first threshold; Export first control signal and control said switching tube and end, and be first timing time of said timing unit the deadline of said switching tube; When deadline of said switching tube during greater than first timing time of said timing unit, said voltage-regulation unit is exported second control signal and is controlled said switching tube conducting, and the ON time of said switching tube is second timing time of said timing unit.
Preferably, said current limliting unit comprises: first switching tube, first resistance and second resistance; Wherein:
Said first switching tube is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance, and its tie point links to each other with power supply;
Perhaps, said first switching tube is a NPN type triode, and its emitter links to each other with an end of said first resistance, its tie point ground connection;
And; One end of the base stage of said first switching tube and said second resistance links to each other; The collector electrode of said first switching tube links to each other with the voltage-regulation unit, and links to each other with the grid of said switching tube, and the other end of said first resistance links to each other with the other end of said second resistance; Its tie point links to each other with timing unit, and links to each other with the source electrode of said switching tube.
Preferably, said timing unit comprises: electric capacity, first diode, second diode, the 3rd resistance, the 4th resistance; Wherein:
The negative pole of said first diode links to each other with said the 3rd resistance; The positive pole of said second diode links to each other with said the 4th resistance, and the positive pole of said first diode links to each other with the negative pole of said second diode and links to each other with an end of said electric capacity, and tie point links to each other with the voltage-regulation unit; The other end of said electric capacity links to each other with power supply; The perhaps other end ground connection of said electric capacity, said the 3rd resistance links to each other with said the 4th resistance, and tie point links to each other with the current limliting unit.
Preferably, said voltage-regulation unit comprises: comparator, the 5th resistance, the 6th resistance, the 7th resistance; Wherein:
One end of said the 5th resistance connects the normal phase input end of said comparator; The other end of said the 5th resistance links to each other with the high supply power voltage input port of said comparator; One end of said the 6th resistance connects the normal phase input end of said comparator, and the other end of said the 6th resistance links to each other with the output of comparator, and said tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance connects the normal phase input end of said comparator, and the other end of said the 7th resistance links to each other with the low suppling voltage input port of said comparator, and the negative-phase input of said comparator links to each other with timing unit.
Preferably, the resistance of the resistance of the 3rd resistance in the said timing unit and the 4th resistance differs 2 ~ 3 one magnitude.
A kind of digital output circuit comprises current foldback circuit, power supply and switching tube, and wherein current foldback circuit comprises: current limliting unit, timing unit and voltage-regulation unit; Wherein:
Said current limliting unit links to each other with power supply, switching tube and the said timing unit of said digital output circuit respectively; Said switching tube connects ground connection after the load; When said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Perhaps, said current limliting unit links to each other with ground, said switching tube and said timing unit respectively, and said switching tube connects power supply after connecing load, and when said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Said voltage-regulation unit links to each other with switching tube with said timing unit, current limliting unit respectively; When said source current during greater than first threshold; Export first control signal and control said switching tube and end, and be first timing time of said timing unit the deadline of said switching tube; When deadline of said switching tube during greater than first timing time of said timing unit, said voltage-regulation unit is exported second control signal and is controlled said switching tube conducting, and the ON time of said switching tube is second timing time of said timing unit.
Preferably, said current limliting unit comprises: first switching tube, first resistance and second resistance; Wherein:
Said first switching tube is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance, and its tie point links to each other with power supply;
Perhaps, said first switching tube is a NPN type triode, and its emitter links to each other with an end of said first resistance, its tie point ground connection;
And; One end of the base stage of said first switching tube and said second resistance links to each other; The collector electrode of said first switching tube links to each other with the voltage-regulation unit, and links to each other with the grid of said switching tube, and the other end of said first resistance links to each other with the other end of said second resistance; Its tie point links to each other with timing unit, and links to each other with the source electrode of said switching tube.
Preferably, said timing unit comprises: electric capacity, first diode, second diode, the 3rd resistance, the 4th resistance; Wherein:
The negative pole of said first diode links to each other with said the 3rd resistance; The positive pole of said second diode links to each other with said the 4th resistance, and the positive pole of said first diode links to each other with the negative pole of said second diode and links to each other with an end of said electric capacity, and tie point links to each other with the voltage-regulation unit; The other end of said electric capacity links to each other with power supply; The perhaps other end ground connection of said electric capacity, said the 3rd resistance links to each other with said the 4th resistance, and tie point links to each other with the current limliting unit.
Preferably, said voltage-regulation unit comprises: comparator, the 5th resistance, the 6th resistance, the 7th resistance; Wherein:
One end of said the 5th resistance connects the normal phase input end of said comparator; The other end of said the 5th resistance links to each other with the high supply power voltage input port of said comparator; One end of said the 6th resistance connects the normal phase input end of said comparator, and the other end of said the 6th resistance links to each other with the output of comparator, and said tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance connects the normal phase input end of said comparator, and the other end of said the 7th resistance links to each other with the low suppling voltage input port of said comparator, and the negative-phase input of said comparator links to each other with timing unit.
Preferably, the resistance of the resistance of the 3rd resistance in the said timing unit and the 4th resistance differs 2 ~ 3 one magnitude.
Can find out that from above-mentioned technical scheme in the current foldback circuit disclosed by the invention, when the digital output circuit overcurrent, current foldback circuit can be limited in electric current in second threshold value through said current limliting unit, the size of current when being able to confirm overcurrent; And control said switching tube through first control signal of comparator output in the voltage-regulation unit and close output by promptly, turn-off speed is fast during with the assurance overcurrent, and need not change fuse; When deadline of said switching tube during greater than first timing time of said timing unit; Said voltage-regulation unit is exported second control signal and is controlled said switching tube conducting, and the ON time of said switching tube is second timing time of said timing unit, if output remains over-current state; Then close output once more; The present invention is through so periodically making repeated attempts, and up to exporting no longer overcurrent, it is definite to make that the output normal time of recovery is able to the time.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the circuit block diagram of digital output circuit disclosed by the invention;
Fig. 2 is the circuit block diagram of current foldback circuit disclosed by the invention;
Fig. 3 is the circuit theory diagrams of the disclosed current limliting of embodiment of the invention unit;
Fig. 4 is the schematic diagram of timing unit for the embodiment of the invention is disclosed;
Fig. 5 is the schematic diagram of the disclosed voltage-regulation of embodiment of the invention unit;
Fig. 6 is the schematic diagram of the disclosed current foldback circuit of the embodiment of the invention;
Fig. 7 is the schematic diagram of the disclosed another kind of current limliting of embodiment of the invention unit;
Fig. 8 is the schematic diagram of the disclosed another kind of current foldback circuit of the embodiment of the invention.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
The invention provides a kind of current foldback circuit, with solve in the available circuit to the load equipment protection inadequately fast, use inconvenient, size of current when being difficult to confirm overcurrent and recover the problem that recovery time of insurance is difficult to confirm certainly.
As shown in Figure 2, current foldback circuit disclosed by the invention comprises: current limliting unit, timing unit and voltage-regulation unit.
Concrete, the current limliting unit is as shown in Figure 3, comprising: first resistance R 1, second resistance R 2, the first switching tube VT1; Wherein, the said first switching tube VT1 is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance R 1; Its tie point links to each other with the power vd D of digital output circuit; The base stage of the said first switching tube VT1 links to each other with an end of said second resistance R 2, and the collector electrode of the said first switching tube VT1 links to each other with the voltage-regulation unit, and links to each other with the grid of switching tube; The other end of said first resistance R 1 links to each other with the other end of said second resistance R 2; Its tie point links to each other with timing unit, and links to each other with the source electrode of switching tube, and said switching tube is the PMOS transistor.Perhaps as shown in Figure 7, the said first switching tube VT1 is a NPN type triode, its tie point ground connection that its emitter links to each other with said first resistance R, 1 one ends, and said switching tube is a nmos pass transistor.
Timing unit is as shown in Figure 4, comprising: the first diode VD1, the second diode VD2, the 3rd resistance R 3, the 4th resistance R 4, capacitor C 1; Wherein, The negative pole of the said first diode VD1 links to each other with said the 3rd resistance R 3, and the positive pole of the said second diode VD2 links to each other with said the 4th resistance R 4, and the positive pole of the said first diode VD1 links to each other with the negative pole of the said second diode VD2 and links to each other with an end of said capacitor C 1; Tie point links to each other with the voltage-regulation unit; The other end of said capacitor C 1 links to each other with the power vd D of digital output circuit, and said the 3rd resistance R 3 links to each other with said the 4th resistance R 4, and tie point links to each other with the current limliting unit.Perhaps when current limliting unit ground connection, the other end of said capacitor C 1 is ground connection also.
The voltage-regulation unit is as shown in Figure 5, comprising: comparator U1, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7; Wherein, One end of said the 5th resistance R 5 connects the normal phase input end of said comparator U1; The other end of said the 5th resistance R 5 links to each other with the high supply power voltage input port VP of said comparator U1; One end of said the 6th resistance R 6 connects the normal phase input end of said comparator U1, and the other end of said the 6th resistance R 6 links to each other with the output of said comparator U1, and tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance R 7 connects the normal phase input end of said comparator U1, and the other end of said the 7th resistance R 7 links to each other with the low suppling voltage input port VN of said comparator U1, and the negative-phase input of said comparator U1 links to each other with timing unit.
Whole current foldback circuit schematic diagram such as Fig. 6 or shown in Figure 8; Wherein, The tie point of said current limliting unit first resistance R 1 and second resistance R 2 is connected to the tie point of said timing unit the 3rd resistance R 3 and the 4th resistance R 4; Said timing unit capacitor C 1 tie point anodal with the said first diode VD1, the second diode VD2 negative pole is connected to the negative-phase input of said voltage-regulation unit comparator U1, and the output of said voltage-regulation unit comparator U1 is connected to the grid of switching tube.
The concrete course of work of current foldback circuit is following:
When the output current of digital output circuit is in (non-overcurrent) under the normal condition, current foldback circuit is inoperative, and the normal function of circuit is not exerted an influence.Under output circuit generation overcurrent condition, if said source current greater than first threshold I1, the electrorheological that then passes through said first resistance R 1 is big; Its two ends pressure drop UR1 also increases; When said current limliting unit linked to each other with power vd D, said capacitor C 1 was via said first diode VD1 and 3 discharges of said the 3rd resistance R, and the magnitude of voltage U1N of causes voltage regulon comparator negative-phase input reduces; Until the magnitude of voltage U1N of negative-phase input magnitude of voltage U1P less than normal phase input end; This moment, said comparator U1 exported the first control signal high level VP, inputed to the grid of said PMOS switching tube, controlled said switching tube and ended; 1 beginning of timing unit capacitor C is charged with the said second diode VD2 via said the 4th resistance R 4 then, and be the first timing time T1 of said timing unit the deadline of said switching tube.
, said switching tube can obtain after ending by Fig. 5; Said the 5th resistance R 5 is parallel to high supply power voltage VP and normal phase input end with said the 6th resistance R 6; The 7th resistance R 7 is connected in low suppling voltage VN and normal phase input end, thus this moment U1P=VN+ (VP-VN) * R7/ ((R5//R6)+R7); When comparator toggles, U1N ≈ U1P ignores the little electric current in the timing unit, first threshold I1 ≈ (VDD-U1P)/R1.
Perhaps when current limliting unit ground connection; If said source current is greater than first threshold I1, first resistance R, 1 two ends pressure drop UR1 increases, electric current said the 4th resistance R 4 and the said second diode VD2 of flowing through; Said capacitor C 1 charging; The magnitude of voltage U1N of causes voltage regulon comparator negative-phase input raises, and is higher than the magnitude of voltage U1P of normal phase input end until the magnitude of voltage U1N of negative-phase input, and this moment, said comparator U1 exported the first control signal low level VN; Input to the grid of nmos switch pipe; Control said switching tube and end, 1 beginning of timing unit capacitor C is discharged via said first diode VD1 and the 3rd resistance R 3 then, and be the first timing time T1 of said timing unit the deadline of said switching tube.
, said switching tube can obtain after ending by Fig. 5; This moment, said the 5th resistance R 5 was connected in high supply power voltage VP and normal phase input end; Said the 6th resistance R 6 is parallel to low suppling voltage VN and normal phase input end with said the 7th resistance R 7, thus this moment U1P=VP-(VP-VN) * R5/ ((R6//R7)+R5); When said comparator toggles, U1N ≈ U1P ignores the little electric current in the timing unit, first threshold I1 ≈ (U1P-GND)/R1.
When current limliting unit and timing unit meet VDD; Experienced after the first timing time TI, said timing unit capacitor C 1 charging finishes, and this moment, the negative-phase input magnitude of voltage U1N of comparator was elevated to soon above normal phase input end UIP magnitude of voltage; Then said comparator U1 exports the second control signal low level VN; Input to the grid of PMOS switching tube, control said switching tube conducting, this moment flow through said first diode VD1 and said the 3rd resistance R 3 of electric current; Said timing unit capacitor C 1 begins discharge, and the ON time of said switching tube is the second timing time T2 of said timing unit.
Can be obtained by Fig. 5 this moment; Said the 5th resistance R 5 connects high supply power voltage VP and normal phase input end; Said the 6th resistance R 6 is parallel in low suppling voltage VN and normal phase input end with said the 7th resistance R 7, thus this moment U1P=VN+ (VP-VN) * (R6//R7)/((R6//R7)+R5).
Perhaps when current limliting unit and timing unit ground connection; After having experienced the first timing time TI, said timing unit capacitor C 1 discharge finishes, and the negative-phase input magnitude of voltage U1N of comparator is reduced to and is about to be lower than normal phase input end UIP magnitude of voltage at this moment; Then said comparator U1 exports the second control signal high level VP; Input to the grid of nmos switch pipe, control said switching tube conducting, this moment flow through said the 4th resistance R 4 and the said second diode VD2 of electric current; Said timing unit capacitor C 1 begins charging, and the ON time of said switching tube is the second timing time T2 of said timing unit.
This moment, said the 5th resistance R 5 was parallel to high supply power voltage VP and normal phase input end with said the 6th resistance R 6, and said the 7th resistance R 7 is in connecting low suppling voltage VN and normal phase input end, thus this moment U1P=VN+ (VP-VN) * R7/ ((R5//R6)+R7).
Within the second timing time T2, if electric current overcurrent is still then closed output once more, wait for the first timing time T1 again after, open output once more.So periodically make repeated attempts and open output, up to output current overcurrent no longer.
When electric current becomes big always, if said source current greater than the second threshold value I2, the pressure drop UR1 at resistance R 1 two ends also becomes big thereupon in the said current limliting unit; When UR1 approached the first switching tube VT1 emitter junction forward voltage drop Veb of positive-negative-positive triode, the said first switching tube VT1 was in open mode, thereby UR1 is limited near the Veb; Just output current is limited in the second current threshold I2 of setting; This moment I2 ≈ Veb/R1, perhaps when current limliting unit ground connection, when UR1 approaches the first switching tube VT1 emitter inverse pressure drop Vbe of NPN type triode; The said first switching tube VT1 is in open mode; Thereby UR1 is limited near the Vbe, just output current is limited in the second current threshold I2 of setting, this moment I2 ≈ Vbe/R1; This moment, the operation principle of each unit was the same during only greater than first threshold I1 with output current, repeated no more here.
The present invention also provides a kind of digital output circuit, and is as shown in Figure 1, comprises input control, drive controlling, switching tube and current foldback circuit, and wherein current foldback circuit comprises: current limliting unit, timing unit and voltage-regulation unit.
Concrete, the current limliting unit is as shown in Figure 3, comprising: first resistance R 1, second resistance R 2, the first switching tube VT1; Wherein, the said first switching tube VT1 is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance R 1; Its tie point links to each other with the power vd D of digital output circuit; The base stage of the said first switching tube VT1 links to each other with an end of said second resistance R 2, and the collector electrode of the said first switching tube VT1 links to each other with the voltage-regulation unit, and links to each other with the grid of switching tube; The other end of said first resistance R 1 links to each other with the other end of said second resistance R 2; Its tie point links to each other with timing unit, and links to each other with the source electrode of switching tube, and said switching tube is the PMOS transistor.Perhaps as shown in Figure 7, the said first switching tube VT1 is a NPN type triode, its tie point ground connection that its emitter links to each other with said first resistance R, 1 one ends, and said switching tube is a nmos pass transistor.
Timing unit is as shown in Figure 4, comprising: the first diode VD1, the second diode VD2, the 3rd resistance R 3, the 4th resistance R 4, capacitor C 1; Wherein, The negative pole of the said first diode VD1 links to each other with said the 3rd resistance R 3, and the positive pole of the said second diode VD2 links to each other with said the 4th resistance R 4, and the positive pole of the said first diode VD1 links to each other with the negative pole of the said second diode VD2 and links to each other with an end of said capacitor C 1; Tie point links to each other with the voltage-regulation unit; The other end of said capacitor C 1 links to each other with the power vd D of digital output circuit, and said the 3rd resistance R 3 links to each other with said the 4th resistance R 4, and tie point links to each other with the current limliting unit.Perhaps when current limliting unit ground connection, the other end of said capacitor C 1 is ground connection also.
The voltage-regulation unit is as shown in Figure 5, comprising: comparator U1, the 5th resistance R 5, the 6th resistance R 6, the 7th resistance R 7; Wherein, One end of said the 5th resistance R 5 connects the normal phase input end of said comparator U1; The other end of said the 5th resistance R 5 links to each other with the high supply power voltage input port VP of said comparator U1; One end of said the 6th resistance R 6 connects the normal phase input end of said comparator U1, and the other end of said the 6th resistance R 6 links to each other with the output of said comparator U1, and tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance R 7 connects the normal phase input end of said comparator U1, and the other end of said the 7th resistance R 7 links to each other with the low suppling voltage input port VN of said comparator U1, and the negative-phase input of said comparator U1 links to each other with timing unit.
Whole current foldback circuit schematic diagram such as Fig. 6 or shown in Figure 8; Wherein, The tie point of said current limliting unit first resistance R 1 and second resistance R 2 is connected to the tie point of said timing unit the 3rd resistance R 3 and the 4th resistance R 4; Said timing unit capacitor C 1 tie point anodal with the said first diode VD1, the second diode VD2 negative pole is connected to the negative-phase input of said voltage-regulation unit comparator U1, and the output of said voltage-regulation unit comparator U1 is connected to the grid of switching tube.
The concrete course of work of current foldback circuit is following:
When the output current of digital output circuit is in (non-overcurrent) under the normal condition, current foldback circuit is inoperative, and the normal function of circuit is not exerted an influence.Under output circuit generation overcurrent condition, if said source current greater than first threshold I1, the electrorheological that then passes through said first resistance R 1 is big; Its two ends pressure drop UR1 also increases; When said current limliting unit linked to each other with power vd D, said capacitor C 1 was via said first diode VD1 and 3 discharges of said the 3rd resistance R, and the magnitude of voltage U1N of causes voltage regulon comparator negative-phase input reduces; Until the magnitude of voltage U1N of negative-phase input magnitude of voltage U1P less than normal phase input end; This moment, said comparator U1 exported the first control signal high level VP, inputed to the grid of said PMOS switching tube, controlled said switching tube and ended; 1 beginning of timing unit capacitor C is charged with the said second diode VD2 via said the 4th resistance R 4 then, and be the first timing time T1 of said timing unit the deadline of said switching tube.
, said switching tube can obtain after ending by Fig. 5; Said the 5th resistance R 5 is parallel to high supply power voltage VP and normal phase input end with said the 6th resistance R 6; The 7th resistance R 7 is connected in low suppling voltage VN and normal phase input end, thus this moment U1P=VN+ (VP-VN) * R7/ ((R5//R6)+R7); When comparator toggles, U1N ≈ U1P ignores the little electric current in the timing unit, first threshold I1 ≈ (VDD-U1P)/R1.
Perhaps when current limliting unit ground connection; If said source current is greater than first threshold I1, first resistance R, 1 two ends pressure drop UR1 increases, electric current said the 4th resistance R 4 and the said second diode VD2 of flowing through; Said capacitor C 1 charging; The magnitude of voltage U1N of causes voltage regulon comparator negative-phase input raises, and is higher than the magnitude of voltage U1P of normal phase input end until the magnitude of voltage U1N of negative-phase input, and this moment, said comparator U1 exported the first control signal low level VN; Input to the grid of nmos switch pipe; Control said switching tube and end, 1 beginning of timing unit capacitor C is discharged via said first diode VD1 and the 3rd resistance R 3 then, and be the first timing time T1 of said timing unit the deadline of said switching tube.
, said switching tube can obtain after ending by Fig. 5; This moment, said the 5th resistance R 5 was connected in high supply power voltage VP and normal phase input end; Said the 6th resistance R 6 is parallel to low suppling voltage VN and normal phase input end with said the 7th resistance R 7, thus this moment U1P=VP-(VP-VN) * R5/ ((R6//R7)+R5); When said comparator toggles, U1N ≈ U1P ignores the little electric current in the timing unit, first threshold I1 ≈ (U1P-GND)/R1.
When current limliting unit and timing unit meet VDD; Experienced after the first timing time TI, said timing unit capacitor C 1 charging finishes, and this moment, the negative-phase input magnitude of voltage U1N of comparator was elevated to soon above normal phase input end UIP magnitude of voltage; Then said comparator U1 exports the second control signal low level VN; Input to the grid of PMOS switching tube, control said switching tube conducting, this moment flow through said first diode VD1 and said the 3rd resistance R 3 of electric current; Said timing unit capacitor C 1 begins discharge, and the ON time of said switching tube is the second timing time T2 of said timing unit.
Can be obtained by Fig. 5 this moment; Said the 5th resistance R 5 connects high supply power voltage VP and normal phase input end; Said the 6th resistance R 6 is parallel in low suppling voltage VN and normal phase input end with said the 7th resistance R 7, thus this moment U1P=VN+ (VP-VN) * (R6//R7)/((R6//R7)+R5).
Perhaps when current limliting unit and timing unit ground connection; After having experienced the first timing time TI, said timing unit capacitor C 1 discharge finishes, and the negative-phase input magnitude of voltage U1N of comparator is reduced to and is about to be lower than normal phase input end UIP magnitude of voltage at this moment; Then said comparator U1 exports the second control signal high level VP; Input to the grid of nmos switch pipe, control said switching tube conducting, this moment flow through said the 4th resistance R 4 and the said second diode VD2 of electric current; Said timing unit capacitor C 1 begins charging, and the ON time of said switching tube is the second timing time T2 of said timing unit.
This moment, said the 5th resistance R 5 was parallel to high supply power voltage VP and normal phase input end with said the 6th resistance R 6, and said the 7th resistance R 7 is in connecting low suppling voltage VN and normal phase input end, thus this moment U1P=VN+ (VP-VN) * R7/ ((R5//R6)+R7).
Within the second timing time T2, if electric current overcurrent is still then closed output once more, wait for the first timing time T1 again after, open output once more.So periodically make repeated attempts and open output, up to output current overcurrent no longer.
When electric current becomes big always, if said source current greater than the second threshold value I2, the pressure drop UR1 at resistance R 1 two ends also becomes big thereupon in the said current limliting unit; When UR1 approached the first switching tube VT1 emitter junction forward voltage drop Veb of positive-negative-positive triode, the said first switching tube VT1 was in open mode, thereby UR1 is limited near the Veb; Just output current is limited in the second current threshold I2 of setting; This moment I2 ≈ Veb/R1, perhaps when current limliting unit ground connection, when UR1 approaches the first switching tube VT1 emitter inverse pressure drop Vbe of NPN type triode; The said first switching tube VT1 is in open mode; Thereby UR1 is limited near the Vbe, just output current is limited in the second current threshold I2 of setting, this moment I2 ≈ Vbe/R1; This moment, the operation principle of each unit was the same during only greater than first threshold I1 with output current, repeated no more here.
To the above-mentioned explanation of the disclosed embodiments, make this area professional and technical personnel can realize or use the present invention.Multiple modification to these embodiment will be conspicuous concerning those skilled in the art, and defined General Principle can realize under the situation that does not break away from the spirit or scope of the present invention in other embodiments among this paper.Therefore, the present invention will can not be restricted to these embodiment shown in this paper, but will meet and principle disclosed herein and features of novelty the wideest corresponding to scope.
Claims (10)
1. a current foldback circuit is characterized in that, is applied to digital output circuit, comprising: current limliting unit, timing unit and voltage-regulation unit, wherein:
Said current limliting unit links to each other with power supply, switching tube and the said timing unit of said digital output circuit respectively; Said switching tube connects ground connection after the load; When said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Perhaps, said current limliting unit links to each other with ground, said switching tube and said timing unit respectively, and said switching tube connects power supply after connecing load, and when said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Said voltage-regulation unit links to each other with switching tube with said timing unit, current limliting unit respectively; When said source current during greater than first threshold; Export first control signal and control said switching tube and end, and be first timing time of said timing unit the deadline of said switching tube; When deadline of said switching tube during greater than first timing time of said timing unit, said voltage-regulation unit is exported second control signal and is controlled said switching tube conducting, and the ON time of said switching tube is second timing time of said timing unit.
2. circuit according to claim 1 is characterized in that, said current limliting unit comprises: first switching tube, first resistance and second resistance; Wherein:
Said first switching tube is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance, and its tie point links to each other with power supply;
Perhaps, said first switching tube is a NPN type triode, and its emitter links to each other with an end of said first resistance, its tie point ground connection;
And; One end of the base stage of said first switching tube and said second resistance links to each other; The collector electrode of said first switching tube links to each other with the voltage-regulation unit, and links to each other with the grid of said switching tube, and the other end of said first resistance links to each other with the other end of said second resistance; Its tie point links to each other with timing unit, and links to each other with the source electrode of said switching tube.
3. circuit according to claim 1 is characterized in that, said timing unit comprises: electric capacity, first diode, second diode, the 3rd resistance, the 4th resistance; Wherein:
The negative pole of said first diode links to each other with said the 3rd resistance; The positive pole of said second diode links to each other with said the 4th resistance, and the positive pole of said first diode links to each other with the negative pole of said second diode and links to each other with an end of said electric capacity, and tie point links to each other with the voltage-regulation unit; The other end of said electric capacity links to each other with power supply; The perhaps other end ground connection of said electric capacity, said the 3rd resistance links to each other with said the 4th resistance, and tie point links to each other with the current limliting unit.
4. circuit according to claim 1 is characterized in that, said voltage-regulation unit comprises: comparator, the 5th resistance, the 6th resistance, the 7th resistance; Wherein:
One end of said the 5th resistance connects the normal phase input end of said comparator; The other end of said the 5th resistance links to each other with the high supply power voltage input port of said comparator; One end of said the 6th resistance connects the normal phase input end of said comparator, and the other end of said the 6th resistance links to each other with the output of comparator, and said tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance connects the normal phase input end of said comparator, and the other end of said the 7th resistance links to each other with the low suppling voltage input port of said comparator, and the negative-phase input of said comparator links to each other with timing unit.
5. circuit according to claim 1 is characterized in that, the resistance of the 3rd resistance in the said timing unit and the resistance of the 4th resistance differ 2 ~ 3 one magnitude.
6. a digital output circuit is characterized in that, comprises current foldback circuit, power supply and switching tube, and wherein current foldback circuit comprises: current limliting unit, timing unit and voltage-regulation unit; Wherein:
Said current limliting unit links to each other with power supply, switching tube and the said timing unit of said digital output circuit respectively; Said switching tube connects ground connection after the load; When said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Perhaps, said current limliting unit links to each other with ground, said switching tube and said timing unit respectively, and said switching tube connects power supply after connecing load, and when said source current during greater than second threshold value, the said source current of said current limliting unit controls is not more than said second threshold value;
Said voltage-regulation unit links to each other with switching tube with said timing unit, current limliting unit respectively; When said source current during greater than first threshold; Export first control signal and control said switching tube and end, and be first timing time of said timing unit the deadline of said switching tube; When deadline of said switching tube during greater than first timing time of said timing unit, said voltage-regulation unit is exported second control signal and is controlled said switching tube conducting, and the ON time of said switching tube is second timing time of said timing unit.
7. circuit according to claim 6 is characterized in that, said current limliting unit comprises: first switching tube, first resistance and second resistance; Wherein:
Said first switching tube is the positive-negative-positive triode, and its emitter links to each other with an end of said first resistance, and its tie point links to each other with power supply;
Perhaps, said first switching tube is a NPN type triode, and its emitter links to each other with an end of said first resistance, its tie point ground connection;
And; One end of the base stage of said first switching tube and said second resistance links to each other; The collector electrode of said first switching tube links to each other with the voltage-regulation unit, and links to each other with the grid of said switching tube, and the other end of said first resistance links to each other with the other end of said second resistance; Its tie point links to each other with timing unit, and links to each other with the source electrode of said switching tube.
8. circuit according to claim 6 is characterized in that, said timing unit comprises: electric capacity, first diode, second diode, the 3rd resistance, the 4th resistance; Wherein:
The negative pole of said first diode links to each other with said the 3rd resistance; The positive pole of said second diode links to each other with said the 4th resistance, and the positive pole of said first diode links to each other with the negative pole of said second diode and links to each other with an end of said electric capacity, and tie point links to each other with the voltage-regulation unit; The other end of said electric capacity links to each other with power supply; The perhaps other end ground connection of said electric capacity, said the 3rd resistance links to each other with said the 4th resistance, and tie point links to each other with the current limliting unit.
9. circuit according to claim 6 is characterized in that, said voltage-regulation unit comprises: comparator, the 5th resistance, the 6th resistance, the 7th resistance; Wherein:
One end of said the 5th resistance connects the normal phase input end of said comparator; The other end of said the 5th resistance links to each other with the high supply power voltage input port of said comparator; One end of said the 6th resistance connects the normal phase input end of said comparator, and the other end of said the 6th resistance links to each other with the output of comparator, and said tie point links to each other with the current limliting unit; And link to each other with the grid of said switching tube; One end of said the 7th resistance connects the normal phase input end of said comparator, and the other end of said the 7th resistance links to each other with the low suppling voltage input port of said comparator, and the negative-phase input of said comparator links to each other with timing unit.
10. circuit according to claim 6 is characterized in that, the resistance of the 3rd resistance in the said timing unit and the resistance of the 4th resistance differ 2 ~ 3 one magnitude.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108418352A (en) * | 2017-07-20 | 2018-08-17 | 益航电子股份有限公司 | Motor device and motor drive circuit |
| CN108574259A (en) * | 2018-06-22 | 2018-09-25 | 深圳市高胜科研电子有限公司 | A kind of protective device of direct current supply, system and control method |
| CN109245055A (en) * | 2018-09-30 | 2019-01-18 | 浙江鲲悟科技有限公司 | Power conversion system, the current foldback circuit of power switch tube and method |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0522853A (en) * | 1991-07-12 | 1993-01-29 | Fujitsu Denso Ltd | Rush current avoiding circuit |
| CN1898857A (en) * | 2003-12-26 | 2007-01-17 | 罗姆股份有限公司 | Overcurrent protection circuit, motor drive circuit, and semiconductor device |
| CN201156667Y (en) * | 2008-02-20 | 2008-11-26 | 新巨企业股份有限公司 | Protective circuit with variable current limiting level |
| CN101355330A (en) * | 2007-07-23 | 2009-01-28 | 张禾 | Protector for starting and limiting current of DC electric machine |
| CN101777782A (en) * | 2009-01-13 | 2010-07-14 | 索尼公司 | Battery pack and method of controlling the same |
| CN102377336A (en) * | 2010-08-06 | 2012-03-14 | 三垦电气株式会社 | Switching power source apparatus |
| CN202276142U (en) * | 2011-11-01 | 2012-06-13 | 无锡富洪科技有限公司 | Electric vehicle, electric vehicle hybrid power source and battery pack current control circuit |
-
2012
- 2012-08-07 CN CN201210279701.4A patent/CN102810851B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0522853A (en) * | 1991-07-12 | 1993-01-29 | Fujitsu Denso Ltd | Rush current avoiding circuit |
| CN1898857A (en) * | 2003-12-26 | 2007-01-17 | 罗姆股份有限公司 | Overcurrent protection circuit, motor drive circuit, and semiconductor device |
| CN101355330A (en) * | 2007-07-23 | 2009-01-28 | 张禾 | Protector for starting and limiting current of DC electric machine |
| CN201156667Y (en) * | 2008-02-20 | 2008-11-26 | 新巨企业股份有限公司 | Protective circuit with variable current limiting level |
| CN101777782A (en) * | 2009-01-13 | 2010-07-14 | 索尼公司 | Battery pack and method of controlling the same |
| CN102377336A (en) * | 2010-08-06 | 2012-03-14 | 三垦电气株式会社 | Switching power source apparatus |
| CN202276142U (en) * | 2011-11-01 | 2012-06-13 | 无锡富洪科技有限公司 | Electric vehicle, electric vehicle hybrid power source and battery pack current control circuit |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110089200A (en) * | 2016-12-15 | 2019-08-02 | 欧姆龙株式会社 | Navigation lamp control system, illuminating lamp control system and switch unit |
| CN108418352A (en) * | 2017-07-20 | 2018-08-17 | 益航电子股份有限公司 | Motor device and motor drive circuit |
| CN107395175B (en) * | 2017-09-04 | 2023-09-22 | 云南电网有限责任公司电力科学研究院 | MOS tube overcurrent protection circuit |
| CN108574259A (en) * | 2018-06-22 | 2018-09-25 | 深圳市高胜科研电子有限公司 | A kind of protective device of direct current supply, system and control method |
| CN109245055A (en) * | 2018-09-30 | 2019-01-18 | 浙江鲲悟科技有限公司 | Power conversion system, the current foldback circuit of power switch tube and method |
| CN109245055B (en) * | 2018-09-30 | 2024-05-31 | 上海鲲悟丰电科技有限公司 | Power conversion system, overcurrent protection circuit and method of power switch tube |
| CN110783884A (en) * | 2019-10-17 | 2020-02-11 | 安徽省航嘉智源科技有限公司 | Short circuit self-recovery method and system |
| CN110783884B (en) * | 2019-10-17 | 2022-06-14 | 安徽省航嘉智源科技有限公司 | Short circuit self-recovery method and system |
| CN112234693A (en) * | 2020-08-28 | 2021-01-15 | 珠海格力电器股份有限公司 | Bus charging control device, driver and bus charging control method thereof |
| CN116627205A (en) * | 2022-02-10 | 2023-08-22 | 比亚迪股份有限公司 | Follower circuit, vehicle power supply circuit and vehicle |
| CN116224011A (en) * | 2023-04-25 | 2023-06-06 | 苏州锴威特半导体股份有限公司 | Power tube overcurrent detection circuit |
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Address after: 4 / F, building 1, No.14 Jiuxianqiao Road, Chaoyang District, Beijing 100020 Patentee after: Beijing Jingwei Hirain Technologies Co.,Inc. Address before: 100101 Beijing city Chaoyang District Anxiang Beili 11 B block 8 layer Patentee before: Beijing Jingwei HiRain Technologies Co.,Ltd. |