CN208316285U - A kind of current foldback circuit of Switching Power Supply - Google Patents
A kind of current foldback circuit of Switching Power Supply Download PDFInfo
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- CN208316285U CN208316285U CN201820872414.7U CN201820872414U CN208316285U CN 208316285 U CN208316285 U CN 208316285U CN 201820872414 U CN201820872414 U CN 201820872414U CN 208316285 U CN208316285 U CN 208316285U
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- current foldback
- power supply
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Abstract
The utility model discloses a kind of current foldback circuits of Switching Power Supply, belong to electronic circuit field, it solves the problems, such as part current foldback circuit not and can control that the length of overcurrent protection time and trial is maintained to be again started up length of time, it is avoided that the overcurrent events false triggering overcurrent protection of short time (ms grades) also to meet needed for particular customer application, its key points of the technical solution are that: including for sample rate current size and being amplified and being exported the amplifier circuit of sampled signal, it is preset with current reference value and is coupled to the amplifier circuit to receive sampled signal and export the comparison circuit of comparison signal, the comparison circuit is coupled to receive comparison signal and export the control circuit of control signal, the utility model can control the length of the guard time of current foldback circuit, attempt the length for being again started up the time, it simultaneously can also The overcurrent events false triggering overcurrent protection of short time (ms grades) is avoided the problem that meet needed for the application of particular customer.
Description
Technical field
The utility model relates to a kind of Switching Power Supply, in particular to a kind of current foldback circuit of Switching Power Supply.
Background technique
Switching Power Supply has all been widely applied in various fields such as various instrument and meters, electronic circuit, control equipment.Now
For Switching Power Supply to there is various topologys, way of realization is each has something to recommend him, but general all includes PWM chip and interlock circuit, and control is opened
The conducting and cut-off of device are closed, and then driving switch transformer realizes voltage conversion, obtains electricity after filtering using secondary commutation
DC voltage required for sub-circuit.
The major defect of the prior art is:
General current foldback circuit not can control maintain the overcurrent protection time length and again attempt to starting the time it is long
Short problem is also unsatisfactory for the requirement that particular customer is unable to the work of trigger protection circuit to the overcurrent events of short time (ms grades),
Therefore there is room for improvement for existing general current foldback circuit.
Utility model content
The purpose of the utility model is to provide a kind of current foldback circuits of Switching Power Supply, can control current foldback circuit
Guard time length, attempt to be again started up the length of time, while being also avoided that the overcurrent events mistake of short time (ms grade)
The problem of triggering overcurrent protection is to meet needed for the application of particular customer.
The above-mentioned technical purpose of the utility model has the technical scheme that
A kind of current foldback circuit of Switching Power Supply, including for sample rate current size and amplified and export sampling letter
Number amplifier circuit, be preset with current reference value and be coupled to the amplifier circuit to receive sampled signal and export
The comparison circuit of comparison signal is coupled to the comparison circuit to receive comparison signal and export the control circuit of control signal；
Only when sampled signal values are greater than current reference value, the control circuit exports the control of the high and low level of accurate pulse width ratio
Signal processed, wherein for protecting, low level is again started up high level for attempting.
Using the above scheme, when circuit works, amplifier circuit carries out sampling to the electric current in circuit in real time and to it
Processing is amplified, is delivered to comparison circuit after amplification, when occurring the phenomenon that overcurrent on circuit, sampled signal values can be greater than electricity
A reference value is flowed, the control signal of control circuit output high level is to disconnect the output of entire circuit, to achieve the effect that protection, this
Circuit reliability is high, stability is high, can control the length of the guard time of current foldback circuit, attempts the length for being again started up the time
It is short, while to meet answering for particular customer the problem of be also avoided that the overcurrent events false triggering overcurrent protection of short time (ms grades)
With required.
Preferably, current foldback circuit further includes being coupled to the amplifier circuit to avoid the protection of overcurrent spike electricity
Road.
Using the above scheme, when be in the presence of in circuit overcurrent when, overcurrent will appear in a flash relatively high electric current,
Electric current amplifying circuit easy to damage, general current foldback circuit can act at once, but part certain applications need to protect
Circuit is failure to actuate this moment, only when overcurrent event duration for a period of time after, protection circuit just protect, by be arranged protection circuit,
It can prevent the generation of the situation.
Preferably, the protection circuit is capacitor.
Using the above scheme, the setting of capacitor has the process of charging and discharging, can play the role of buffering.
Preferably, current foldback circuit further includes being coupled to the control circuit with the anti-of control circuit described in delayed startup
False triggering circuit.
Using the above scheme, the setting of anti-error trigger circuit can prevent the false triggering of control circuit, and it is steady to play raising circuit
Qualitatively effect.
Preferably, current foldback circuit further includes the delay for being coupled to the control circuit to extend high-level control signal
Circuit.
Using the above scheme, the setting of delay circuit can extend the output time of high-level control signal, to extend
Guard time.
Preferably, current foldback circuit further includes being coupled to the control circuit to receive the current limliting triggering electricity of control signal
Road.
Using the above scheme, the setting of current limliting trigger circuit further decreases current value, to further increase entire electricity
The stability on road.
Preferably, the control circuit is 555 timers.
Using the above scheme, the stability of 555 timers is high, and effect is good.
Preferably, the control circuit further includes the filter circuit that promising 555 timer is filtered.
Using the above scheme, filter circuit is used to remove the interference signal in voltage, to further increase control circuit
Stability.
In conclusion the utility model has the following beneficial effects:
When circuit works, amplifier circuit carries out the electric current in circuit to sample and amplify it processing in real time,
Comparison circuit is delivered to after amplification, when occurring the phenomenon that overcurrent on circuit, sampled signal values can be greater than current reference value, control
The control signal of circuit output high level is to disconnect the output of entire circuit, to achieve the effect that protection, this circuit reliability is high,
Stability is high, while controlling the length of the guard time of current foldback circuit, attempting the length for being again started up the time, while can also
The overcurrent events false triggering overcurrent protection of short time (ms grades) is avoided the problem that meet needed for the application of particular customer.
Detailed description of the invention
Fig. 1 is amplifier circuit in the current foldback circuit of Switching Power Supply, the circuit connection diagram for protecting circuit；
Fig. 2 is the circuit connection diagram of comparison circuit in the current foldback circuit of Switching Power Supply；
Fig. 3 is anti-error trigger circuit, control circuit, the circuit connection of delay circuit in the current foldback circuit of Switching Power Supply
Figure；
Fig. 4 is the current limliting trigger circuit in the current foldback circuit of Switching Power Supply.
In figure: 1, amplifier circuit；2, circuit is protected；3, comparison circuit；4, anti-error trigger circuit；5, control circuit；
51, filter circuit；6, delay circuit；7, current limliting trigger circuit.
Specific embodiment
The utility model is described in further detail below in conjunction with attached drawing.
As shown in Figure 1, a kind of current foldback circuit of Switching Power Supply, including amplifier circuit 1, protection circuit 2.
Dual operational amplifier is used in the present embodiment, model LM358 has been internally integrated amplifier U1A and comparator
U1B(is shown in Fig. 2).
Electric current of the amplifier circuit 1 for passing through in real-time Acquisition Circuit simultaneously amplifies processing to the electric current, packet
Current sampling resistor R0, above-mentioned amplifier U1A are included, current sampling resistor R0 is series in a certain section of circuit of Switching Power Supply；It puts
One end that the pin 5 of big device U1A is connected to resistance R0 by connecting resistance R1, pin 6 are connected to resistance by series resistance R2
The other end of R0, is in series with resistance R3 between pin 6 and pin 7, pin 7 exports amplified signal u1 by series resistance R4 again.
The overcurrent events that protection circuit 2 is used to avoid in short-term cause protection circuit to come into force comprising capacitor C1, capacitor C1's
It is parallel to resistance R3.
As shown in Fig. 2, current foldback circuit further includes comparison circuit 3.
Comparison circuit 3 is for amplified signal u1 to be compared with current reference value preset in comparison circuit 3 comprising
Above-mentioned comparator U1B, pin 2 are coupled to amplified signal u1；Pin 3 is used for input current a reference value, passes through series resistance
Power supply VCC is connected to after R5, also series resistance R6 is connected to ground terminal GND to the pin 3 simultaneously, to improve the accurate of comparison circuit 3
Property, it is parallel with filter capacitor C2 over resistor r 6；Pin 8 is connected to power supply VCC；Pin 4 is connected to ground terminal GND；Pin 1 passes through
Series resistance R7 exports comparison signal u2.When the value of amplified signal u1 is greater than the current reference value that pin 3 inputs, comparison signal
U2 exports low level.
As shown in figure 3, current foldback circuit further includes anti-error trigger circuit 4, control circuit 5, delay circuit 6.
Anti-error trigger circuit 4 is used for delayed startup control circuit 5, including resistance R8, capacitor C4 and general-purpose diode D1.Electricity
One end of resistance R8 is connected to power supply VCC and the other end is connected to one end of capacitor C4, and the other end of capacitor C4 is connected to ground terminal
GND, diode D1 are parallel to resistance R8, and cathode terminal is connected to power supply VCC.The delay duration of anti-error trigger circuit 4 is by resistance
R8, capacitor C4 are determined.
Control circuit 5 is controlled by comparison signal u2 comprising 555 timer U1A, filter circuit 51.555 timer U1A
Pin 2 be coupled to comparison signal u2；Pin 4 is connected to the anode tap of diode D1；Pin 8 is connected to power supply VCC；Pin 3
Output is control signal u3；Pin 1 is connected to ground terminal GND；Pin 5 is connected to ground terminal GND by series capacitance C5.
Filter circuit 51 is shunt capacitance C6, and the both ends of shunt capacitance C6 are connected to the pin 8 and ground of 555 timers
Hold GND.
Delay circuit 6 is used to extend the high level output time of 555 timers comprising resistance R9, resistance R10, capacitor
C7, the both ends of resistance R9 are connected to the pin 7 of power supply VCC and 555 timers；The both ends of resistance R10 are connected to 555
The pin 7 and pin 6 of timer；The both ends of capacitor C7 are connected to the pin 6 and ground terminal GND of 555 timers.555 timings
The high level of device extends the time by resistance R9, resistance R10 and capacitor C7 co-determination.
When the input of the pin 2 of 555 timers is low level, pin 3 instantaneously exports high level.
As shown in figure 4, current foldback circuit further includes current limliting trigger circuit 7.
Current limliting trigger circuit 7 is used to carry out current limliting, including resistance R11, Current Limiting Diodes D2. resistance to control signal u3
One end of R11 is coupled to the anode tap that control its other end of signal u3 is connected to Current Limiting Diodes D2, the yin of Current Limiting Diodes D2
It is extremely the output end of entire current foldback circuit.
The course of work:
When circuit works, amplifier circuit 1 carries out the electric current in circuit to sample and amplify it processing in real time,
Protection circuit 2 is used to avoid overcurrent events in short-term, after there is the phenomenon that overcurrent on circuit and continuing for some time, sampled signal
Value can be greater than current reference value, and comparison circuit 3 exports low level comparison signal u2, so that 555 timing circuit pins 3 be made to export
The control signal of the fixed high level of pulse width is to disconnect the output of entire circuit, to achieve the effect that protection.
This specific embodiment is only the explanation to the utility model, is not limitations of the present invention, ability
Field technique personnel can according to need the modification that not creative contribution is made to the present embodiment after reading this specification, but
As long as all by the protection of Patent Law in the scope of the claims of the utility model.
Claims (8)
1. a kind of current foldback circuit of Switching Power Supply, it is characterized in that: including for sample rate current size and being amplified and defeated
Out the amplifier circuit (1) of sampled signal, be preset with current reference value and be coupled to the amplifier circuit (1) with receive
Sampled signal simultaneously exports the comparison circuit (3) of comparison signal, is coupled to the comparison circuit (3) to receive comparison signal and export
Control the control circuit (5) of signal；Only when sampled signal values are greater than current reference value, control circuit (5) output is accurate
The control signal of the high and low level of pulse width ratio, wherein for protecting, low level is again started up high level for attempting.
2. the current foldback circuit of a kind of Switching Power Supply according to claim 1, it is characterized in that: current foldback circuit also wraps
Include the protection circuit (2) for being coupled to the amplifier circuit (1) to avoid overcurrent spike.
3. the current foldback circuit of a kind of Switching Power Supply according to claim 2, it is characterized in that: the protection circuit (2)
For capacitor.
4. the current foldback circuit of a kind of Switching Power Supply according to claim 1, it is characterized in that: current foldback circuit also wraps
Include the anti-error trigger circuit (4) for being coupled to the control circuit (5) with control circuit described in delayed startup (5).
5. the current foldback circuit of a kind of Switching Power Supply according to claim 1, it is characterized in that: current foldback circuit also wraps
It includes and is coupled to the control circuit (5) to extend the delay circuit (6) of high-level control signal.
6. the current foldback circuit of a kind of Switching Power Supply according to claim 1, it is characterized in that: current foldback circuit also wraps
Include the current limliting trigger circuit (7) for being coupled to the control circuit (5) to receive control signal.
7. the current foldback circuit of a kind of Switching Power Supply according to claim 1, it is characterized in that: the control circuit (5)
For 555 timers.
8. the current foldback circuit of a kind of Switching Power Supply according to claim 7, it is characterized in that: the control circuit (5)
It further include the filter circuit (51) that promising 555 timer is filtered.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201820872414.7U CN208316285U (en) | 2018-06-06 | 2018-06-06 | A kind of current foldback circuit of Switching Power Supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201820872414.7U CN208316285U (en) | 2018-06-06 | 2018-06-06 | A kind of current foldback circuit of Switching Power Supply |
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| Publication Number | Publication Date |
|---|---|
| CN208316285U true CN208316285U (en) | 2019-01-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201820872414.7U Active CN208316285U (en) | 2018-06-06 | 2018-06-06 | A kind of current foldback circuit of Switching Power Supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111342430A (en) * | 2020-03-23 | 2020-06-26 | 珠海格力电器股份有限公司 | Overcurrent protection circuit based on switching power supply output end |
-
2018
- 2018-06-06 CN CN201820872414.7U patent/CN208316285U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111342430A (en) * | 2020-03-23 | 2020-06-26 | 珠海格力电器股份有限公司 | Overcurrent protection circuit based on switching power supply output end |
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