CN208571916U - The compensation circuit of overcurrent protection - Google Patents
The compensation circuit of overcurrent protection Download PDFInfo
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Abstract
A kind of compensation circuit of overcurrent protection; including voltage signal sampling bleeder circuit, sampled signal amplifying circuit and circuit for signal conditioning; wherein; voltage signal sampling bleeder circuit is three-port network; input terminal of the one end as compensation circuit, to receive voltage sampling signal, one end ground connection; output end of the other end as voltage signal sampling bleeder circuit, connect with sampled signal amplifying circuit；Sampled signal amplifying circuit is three-port network, and one end is the feeder ear of sampled signal amplifying circuit, and one end is connect with voltage signal sampling bleeder circuit, and output end of the other end as sampled signal amplifying circuit is connect with circuit for signal conditioning；Circuit for signal conditioning is two-port network, and one end is connect with sampled signal amplifying circuit, output end of the other end as compensation circuit.The compensation circuit of the utility model compared with the prior art gets rid of the limitation for compensating electric current in current existing scheme by resistance adjustment, can be divided with biggish resistance.
Description
Technical Field
The utility model relates to a switching power supply, in particular to overcurrent protection's that switching power supply converter was used compensating circuit.
Background
The flyback switching power supply is used as a topology type with the largest consumption in the switching power supply, has the advantages of simple circuit structure, low cost, small design difficulty and high reliability, and is widely applied to power supply systems in various electronic industries such as consumer electronics, white home appliances, LED illumination, instruments and meters, industrial control, smart home, mobile communication and the like.
In different application areas, the input voltage of the flyback switching power supply may be different, for example, the commercial power in japan is 110V, and the commercial power in china is 220V. And considering the fluctuation factor of the power grid voltage, the global input voltage range is 90V-264V. In order to ensure the working stability of the power supply and the safety of the power product at the power output end, the power supply needs an overcurrent protection function with higher consistency, so that the power output power of the power supply is not too large when the electrical appliance is in an abnormal working state, and the risk of fire and the failure of the power product is caused. However, when the flyback power supply is in the full voltage input range of 90V to 264V, the overcurrent protection consistency is relatively poor under the influence of the change of the input voltage.
As shown in fig. 1, the overcurrent protection of the flyback power supply samples the voltage from the sampling resistor Rcs, compares the value of the sampled voltage with the limit value Vth _ OC _ Max inside the power control chip IC1, and turns over and starts the overcurrent protection circuit inside the power control chip IC1 when the sampled voltage is greater than the limit value, and turns off the power supply output, thereby implementing the overcurrent protection function of the power supply. And the reliability of the power supply under the overload condition is ensured.
As shown in fig. 2, it is a graph of voltage waveforms across the sampling resistor Rcs at different input voltages, VH refers to the maximum peak voltage actually generated across the sampling resistor Rcs at high input voltages, and VL refers to the maximum peak voltage actually generated across the sampling resistor Rcs at low input voltages. Vth _ OC _ Max Is a maximum peak threshold voltage of a sampling resistor Rcs set inside the power control chip IC1, Td Is a delay time generated from when the voltage of the current sampling pin Is of the power control chip IC1 reaches Vth _ OC _ Max until a main power MOS transistor in the power supply Is turned off, and Td Is substantially constant for the same fixed power system. It is because of the existence of this delay and the difference in slope of the voltage across the sampling resistor Rcs (the slope k is Vin/L, Vin is the input voltage of the power supply, and L is the primary inductance of the transformer), the maximum peak values of the voltage generated across the sampling resistor Rcs within the same delay time Td are different. The actual voltage on the sampling resistor Rcs during overcurrent is:
from the above formula, it can be seen that the maximum peak voltage value sampled by the sampling resistor Rcs is higher as the input voltage is higher, so that the overcurrent protection point of the actual output current is increased when the input voltage is higher, and the problem of inconsistency of the overcurrent protection points of the power supply when the high-voltage and low-voltage inputs are different occurs.
Therefore, for the flyback switching power supply, in order to ensure that the overcurrent protection point of the flyback switching power supply Is consistent when the overcurrent protection point Is at different input voltages, an overcurrent protection compensation circuit needs to be added, and at present, it Is common practice to introduce the overcurrent protection monitoring pin of the power control chip directly through a resistor from a bus Vbus behind a rectifier bridge, as shown in fig. 1, connect a resistor R1 to a current sampling pin Is of the power control chip IC1 from the bus, and compensate the input voltage signal to a pin Is of the power control chip IC1, so that the final sampling signal of the pin Is the superposition of the voltage signal of a resistor Rcs and the compensation signal of a resistor R1, but because the current always flows through the resistor R1 to compensate the current sampling pin Is under the condition of high input voltage or low input voltage. That Is to say, when high voltage and low voltage are input, the current compensation signal Is always compensated to the current sampling pin Is, but the magnitude of the compensated current Is different.
As described above, in the flyback switching power supply in the industry of the prior art, either the overcurrent protection compensation circuit is not added, the voltage of the resistor Rcs is directly sampled for overcurrent protection, or the voltage of the bus is sampled by the resistor for overcurrent protection compensation, so that the compensation effect is not obvious. Therefore, the problems that the overcurrent protection point of the flyback power supply in the prior art is relatively poor when high voltage is input, the overcurrent protection point is relatively small when low voltage is input, the consistency of the overcurrent protection point is relatively poor, and the reliability of the power supply is not high are caused.
SUMMERY OF THE UTILITY MODEL
In view of the technical defect that above-mentioned prior art exists, the utility model provides a simple structure's overcurrent protection's compensating circuit can solve current overcurrent protection circuit and lead to the inconsistent problem of overcurrent protection point along with input voltage changes.
In order to achieve the above object, the present invention adopts a compensation method of a common collector amplifying circuit, so as to obtain an overcurrent protection point with higher consistency under high and low voltage conditions. The method is implemented by the following technical scheme:
a compensating circuit for overcurrent protection comprises a voltage signal sampling voltage division circuit, a sampling signal amplifying circuit and a signal regulating circuit, wherein the voltage signal sampling voltage division circuit is a three-port network, one end of the voltage signal sampling voltage division circuit is used as the input end of the compensating circuit and used for receiving a voltage sampling signal, one end of the voltage signal sampling voltage division circuit is grounded, and the other end of the voltage signal sampling voltage division circuit is used as the output end of the voltage signal sampling voltage division circuit and is connected with the sampling signal amplifying circuit; the sampling signal amplifying circuit is a three-port network, one end of the sampling signal amplifying circuit is a power supply end of the sampling signal amplifying circuit, one end of the sampling signal amplifying circuit is connected with the voltage signal sampling voltage division circuit, and the other end of the sampling signal amplifying circuit is used as an output end of the sampling signal amplifying circuit and is connected with the signal regulating circuit; the signal regulating circuit is a two-port network, one end of the signal regulating circuit is connected with the sampling signal amplifying circuit, and the other end of the signal regulating circuit is used as the output end of the compensating circuit; wherein,
the voltage signal sampling voltage division circuit is used for dividing an input voltage sampling signal into a low voltage signal which is in direct proportion to the input voltage and is used by the sampling signal amplification circuit;
the sampling signal amplifying circuit is used for converting a voltage signal generated by the voltage signal sampling voltage division circuit into a current signal and amplifying the current signal;
and the signal adjusting circuit is used for adjusting the current signal amplified by the sampling signal amplifying circuit, outputting a compensation current signal through the output end of the compensation circuit and compensating the current signal on the sampling resistor Rcs of the power supply.
As a first embodiment of the compensation circuit, a voltage input signal samples a bus input voltage rectified from a power supply, and a voltage signal input port is sequentially connected with a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a power ground port and a Q1. The sampling signal amplifying circuit is sequentially connected with a signal regulating circuit R4, a capacitor C1, a resistor R2, a resistor R3 and an amplifying circuit power supply port. The regulating circuit is composed of a resistor R4 and sends out the final compensation signal.
Preferably, the compensation circuit samples the input signal from the power bus voltage Vbus.
Preferably, the three-port network is an amplifying circuit composed of NPN type triode.
Preferably, the three-port network is a voltage division circuit composed of resistors.
Preferably, the two-port network is a voltage regulating circuit composed of resistors.
Preferably, the power supply port of the amplifying circuit is from a direct current voltage VCC rectified by an auxiliary winding for supplying power to the power supply control chip.
Preferably, the compensation circuit may be integrated within an integrated circuit.
As a second embodiment of the compensation circuit, a voltage input signal samples a voltage VCC from a power supply port of a power supply auxiliary winding, and the voltage input signal port is sequentially connected with a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a power supply ground port and a Q1. The sampling signal amplifying circuit is sequentially connected with a signal regulating circuit R4, a capacitor C1, a resistor R2, a resistor R3 and an amplifying circuit power supply port. The regulating circuit is composed of a resistor R4 and sends out the final compensation signal.
Preferably, the power supply port of the amplifying circuit is from the voltage Vcc of the power auxiliary power supply winding.
As a third embodiment of the compensation circuit, the power supply port of the amplification circuit is from the reference voltage Vref of the power control chip.
Preferably, the sampling signal is derived from a bus voltage Vbus rectified by a power supply.
As a fourth embodiment of the compensation circuit, the power supply port of the amplification circuit is from the reference voltage Vref of the power control chip.
Preferably, the sampling signal is from a power supply auxiliary winding VCC.
The utility model also provides an overcurrent protection's compensating circuit, including voltage signal sampling bleeder circuit, sampling signal amplifier circuit and signal conditioning circuit, voltage signal sampling bleeder circuit includes resistance R1, resistance R2, resistance R3 and electric capacity C1, sampling signal amplifier circuit includes triode Q1, signal conditioning circuit includes resistance R4, its concrete connection relation is that the input of compensating circuit is drawn forth to resistance R1's one end, for receive sampling signal, resistance R1's the other end is ground connection behind series resistance R2 and resistance R3 in proper order, resistance R2 forms the partial pressure point with resistance R3's series connection point; the capacitor C1 is connected in parallel with two ends of the resistor R3; the base electrode of the triode Q1 Is connected with a voltage division point, the collector electrode of the triode Q1 Is led out to be a power supply end, the emitter electrode of the triode Q1 Is connected with one end of the resistor R4, the other end of the resistor R4 Is led out to be the output end of the compensation circuit, and the output end of the compensation circuit Is used for being sent to a current sampling pin Is of the power chip IC1 together with the power sampling resistor Rcs.
Preferably, the input end of the compensation circuit is connected to the power bus voltage Vbus or to the dc voltage VCC rectified by the power auxiliary winding.
Preferably, the power supply end of the sampling signal amplifying circuit is connected with a direct current voltage VCC rectified by the power supply auxiliary winding or connected with a reference voltage Vref of the power supply control chip.
Compared with the prior art, the utility model discloses overcurrent protection's compensating circuit has following beneficial effect:
the utility model discloses compensating circuit can realize the compensation of single voltage point for 110V is uncompensated, only compensates at 220V, thereby has improved the defect that 110V and 220V all compensate in the present scheme, has realized the higher overcurrent protection point of flyback power uniformity.
The utility model discloses compensating circuit, used device is simple, and the circuit is with low costs.
The utility model discloses compensating circuit breaks away from the limitation through resistance adjustment compensating current in the present current scheme, can carry out the partial pressure with great resistance to make compensating circuit's consumption lower, power efficiency is higher.
The utility model discloses compensating circuit, compensation proportion regulation is more nimble, can be through adjustment compensation regulating circuit's resistance to reach the purpose of adjustment compensation.
The utility model discloses compensating circuit, functional unit realizes inside integrated circuit very easily, can integrate inside integrated circuit, reduces switching power supply device quantity.
Drawings
Fig. 1 is a schematic circuit diagram of a conventional flyback power supply with an overcurrent protection compensation function;
fig. 2 is an analysis diagram of the reasons for the inconsistency of the overcurrent protection point and the low voltage of the conventional flyback power supply;
fig. 3 is a schematic circuit block diagram of a compensation circuit for overcurrent protection implemented by the present invention;
fig. 4 is a schematic diagram of a compensation circuit for overcurrent protection according to a first embodiment of the present invention;
fig. 5 is a schematic diagram of a compensation circuit for overcurrent protection according to a second embodiment of the present invention;
fig. 6 is a schematic diagram of a compensation circuit for overcurrent protection according to a third embodiment of the present invention;
fig. 7 is a schematic diagram of a compensation circuit for overcurrent protection according to a fourth embodiment of the present invention.
Detailed Description
In order to make the present invention more clearly understood, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
First embodiment
Fig. 4 is a compensation circuit for overcurrent protection according to a first embodiment of the present invention, which includes a voltage signal sampling divider circuit, a sampling signal amplifier circuit, and a signal conditioning circuit.
The voltage signal sampling voltage division circuit comprises four devices of a resistor R1, a resistor R2, a resistor R3 and a capacitor C1. The three devices of the resistor R1, the resistor R2 and the resistor R3 are connected in series, one port of the resistor R1 is connected to a sampling input end of an input voltage signal, and the input voltage signalThe voltage signal of the sampling input end comes from the bus capacitor voltage Vbus after the power supply is rectified, and the other end of the resistor R1 is connected to the resistor R2; one end of the resistor R2 is connected to the resistor R1, and the other end is connected to the resistor R3 and the capacitor C1; one end of the resistor R3 is connected with the resistor R2 and the capacitor C1, and the other end is connected with a circuit ground wire; one end of the capacitor C1 is connected to the circuit ground, and the other end is connected to the resistor R2 and the resistor R3. The voltage signal voltage division sampling circuit is used for dividing the voltage of an input voltage signal, converting the voltage into a low-voltage signal in direct proportion to the input voltage, and supplying the low-voltage signal to the sampling signal amplifying circuit. The resistors R1, R2, and R3 function to divide the sampled input voltage signal in equal proportion, and the series connection point of the resistor R2 and the resistor R3 forms a voltage dividing point, so that the voltage dividing signal proportional to the input voltage signal is sent to the sampling signal amplifying circuit through the voltage dividing points of the resistors R2 and R3. The utility model discloses overcurrent protection's compensating circuit, voltage signal sampling bleeder circuit can adopt two 1M's resistance to establish ties and use, and the compensating circuit consumption is PLOSS＝(VBUS-Vcc)2/(R1+R2) Due to VBUS-VCCThe voltage be the fixed value, and the utility model discloses in with the resistance value for current traditional compensating circuit's 10 times, make the compensation loss reduce for traditional compensating circuit's one tenth, power efficiency is higher. The capacitor C1 is used for filtering peaks of the sampled input voltage signal, so that the phenomenon that the peak voltage is caused by instantaneous high-voltage input to cause circuit misoperation is avoided.
The sampling signal amplifying circuit comprises an amplifying circuit power supply port VCC and a triode Q1. for signal amplification, wherein the base of a triode Q1 is connected with a common node consisting of resistors R2 and R3 and a capacitor C1 of a voltage signal sampling voltage division circuit, the collector of a triode Q1 is connected with the amplifying circuit power supply port VCC, the emitter of a triode Q1 is connected with a signal regulating circuit, the sampling signal amplifying circuit is used for converting a voltage signal generated by the bus voltage division circuit into a current signal and amplifying the current signal, the voltage signal with high and low reaction input voltages output by the voltage signal sampling voltage division circuit flows into the base of a triode Q1 according to the difference of the voltage levels and is converted into a current signal Ib reflecting the high and low reaction input voltages, the higher the current signal is, the lower the input voltage signal is, the current signal is amplified into Ie through a triode Q1, Ie is amplified into Ie (1+ β) Ib. and finally transmitted to the signal regulating circuit, and the collector of the amplifying circuit Q1 is connected with the VCC for providing stable power supply for the amplifying circuit.
The signal conditioning circuit includes a resistor R4. One end of the adjusting resistor R4 is connected with the emitter of the triode Q1 of the sampling signal amplifying circuit, and the other end is the output end of the compensating circuit. The signal adjusting circuit is used for adjusting the current signal amplified by the sampling signal amplifying circuit, taking the current signal as a compensation current signal, outputting the compensation current signal through the output end of the compensation circuit, and finally compensating a voltage signal reflecting the current on a sampling resistor Rcs of the switching power supply. The signal adjusting circuit is mainly used for adjusting the output current of the sampling signal amplifying circuit. The purpose of adjusting and compensating can be achieved by adjusting the resistance of the signal adjusting circuit, and the compensation proportion is adjusted flexibly.
Compared with the prior art, the utility model discloses overcurrent protection's compensating circuit can realize the compensation of single voltage point for 110V is uncompensated, only compensates at 220V, thereby has improved the defect that 110V and 220V all carried out the compensation in the present scheme, has realized swashing the higher overcurrent protection point of power uniformity in the full input voltage range of 90V ~ 264V. Just the utility model discloses overcurrent protection's compensating circuit, owing to there is triode amplifier circuit's existence, enlargies compensating current through the enlarged effect of triode to reach required compensation effect, consequently voltage signal sampling bleeder circuit's resistance value does not receive compensating current's restriction, can select the great resistance of resistance, thereby further reduces the loss that compensating circuit well resistance produced, improves power efficiency. In order to ensure the compensation effect, the existing compensation circuit needs to ensure that a compensation current value of about 1.5mA is provided for the resistor Rcs, so that the value of the compensation resistor in the existing scheme is bus voltage Vbus/I, which is finally calculated to be about 200K and affected by resistance withstand voltage and power consumption, and the existing scheme usually adopts two 100K resistors connected in series. If the value of the compensation resistor of the existing compensation circuit is too large, the compensation current is too small, and the compensation effect cannot be achieved.
As follows, the compensation circuit of the first embodiment of the present invention compares the technical effects with the conventional compensation circuit shown in fig. 1 and the test data of each sample when there is no compensation circuit, as shown in table 1 below:
TABLE 1
As in table 1 above, in the same power system, the actual overcurrent protection point of the compensation circuit of the first embodiment of the present invention, which adopts the uncompensated circuit, the conventional compensation circuit, is subjected to the comparison test. Test results show that under the condition of alternating current input voltages of 110V and 220V, the over-current protection point of the uncompensated circuit has a difference of 0.98A between 110V and 220V; the difference between the overcurrent protection points of the traditional compensation circuit at 110V and 220V is 0.63A; the utility model discloses overcurrent protection point only differs 0.14A when 110V and 220V in the first embodiment. Therefore, the beneficial effects of the first embodiment of the present invention are more obvious.
The first embodiment is characterized in that the input voltage signal is sampled from the bus high-voltage direct current voltage rectified by the rectifier bridge.
Second embodiment
Fig. 5 shows a compensation circuit for overcurrent protection according to a second embodiment of the present invention, in which the main circuit is the same as the first embodiment, and the difference from the first embodiment is that the input voltage signal is sampled from the dc VCC rectified from the low voltage signal output by the power auxiliary winding. A compensating circuit for overcurrent protection comprises a voltage signal sampling voltage division circuit, a sampling signal amplifying circuit and a signal adjusting circuit.
The voltage signal sampling voltage division circuit comprises four devices of a resistor R1, a resistor R2, a resistor R3 and a capacitor C1. The three devices of the resistor R1, the resistor R2 and the resistor R3 are connected in series, one port of the resistor R1 is connected to a sampling input end of an input voltage signal, the voltage signal sampled by the input voltage signal is from a voltage signal VCC rectified by a power supply auxiliary winding, and the other end of the voltage signal is connected to the resistor R2; one end of the resistor R2 is connected to the resistor R1, and the other end is connected to the resistor R3 and the capacitor C1; one end of the resistor R3 is connected with the resistor R2 and the capacitor C1, and the other end is connected with a circuit ground wire; one end of the capacitor C1 is connected to the circuit ground, and the other end is connected to the resistor R2 and the resistor R3. The resistors R1, R2, and R3 function to divide the sampled input voltage signal in equal proportion, and the series connection point of the resistor R2 and the resistor R3 forms a voltage dividing point, so that a voltage signal proportional to the magnitude of the input voltage is sent to the sampling signal amplifying circuit through the voltage dividing points of R2 and R3. The capacitor C1 is used for filtering peaks of the sampled input voltage signal, so that the phenomenon that the peak voltage is caused by instantaneous high-voltage input to cause circuit misoperation is avoided.
The sampling signal amplifying circuit comprises an amplifying circuit power supply port VCC and a triode for signal amplification Q1., wherein the base of a triode Q1 is respectively connected with one end of a resistor R2, a resistor R3 and a capacitor C1 of a voltage signal sampling voltage division circuit, the collector of a triode Q1 is connected with the amplifying circuit power supply port VCC, the emitter of a triode Q1 is connected with a signal regulating circuit, a voltage signal reflecting the high and low input voltages output by the voltage signal sampling voltage division circuit flows into the base of a triode Q1 according to the difference of the voltages and is converted into a current signal Ib reflecting the high and low input voltages, the higher the input voltage is, the lower the input voltage signal is, the current signal is smaller, the Ie is amplified into Ie through a triode Q1, the Ie is (1+ β) Ib. and is finally sent to the signal regulating circuit, the collector of a triode Q1 is connected to the amplifying circuit power supply port VCC, and stable power supply is provided for the amplifying circuit.
The signal conditioning circuit includes a resistor R4. One end of the adjusting resistor R4 is connected with an emitting electrode of a triode Q1 of the sampling signal amplifying circuit, the other end of the adjusting resistor R4 is an output end of the compensating circuit, and the signal adjusting circuit is mainly used for adjusting the size of output current.
The second embodiment is characterized in that the input voltage signal is sampled from direct current VCC obtained by rectifying a low-voltage signal output by the auxiliary winding of the power supply. The sampling circuit has the advantages that the sampling signal comes from direct current VCC obtained after rectification of a low-voltage signal output by a power supply auxiliary winding, the voltage value of the signal sampling point VCC is low, generally 5-30V, the magnitude of output current can be reflected, a good signal acquisition feedback effect is achieved, meanwhile, the voltage value is lower than that of the first implementation example, the power consumed by the sampling circuit is lower, and the efficiency of a power supply is improved.
Third embodiment
Fig. 6 shows a compensation circuit for overcurrent protection according to a third embodiment of the present invention, in which the main circuit is the same as the first embodiment, and the difference from the first embodiment is that the power supply of the sampling signal amplifying circuit of the third embodiment is from the reference voltage output port Vref of the power control chip. The advantage of this embodiment over the first embodiment is that the power supply of the sampling signal amplifying circuit comes from the reference voltage output port Vref of the power control chip, the voltage of this port is more stable than VCC, and the operation of the amplifying circuit is not affected by the fluctuation of VCC caused by the outside world, so the operation of the amplifying circuit is also more stable.
Fourth embodiment
Fig. 7 shows a fourth embodiment of the present invention, in which the main circuit is the same as the second embodiment, and the difference from the second embodiment is that the power supply of the sampling signal amplifying circuit of the fourth embodiment is from the reference voltage output port Vref of the power control chip. The advantage of this embodiment over the second embodiment is that the power supply of the sampling signal amplifying circuit comes from the reference voltage output port Vref of the power control chip, the voltage of this port is more stable than VCC, and the operation of the amplifying circuit is not affected by the fluctuation of VCC caused by the outside world, so the operation of the amplifying circuit is also more stable.
Claims (7)
1. The utility model provides an overcurrent protection's compensating circuit which characterized in that: comprises a voltage signal sampling voltage-dividing circuit, a sampling signal amplifying circuit and a signal regulating circuit,
the voltage signal sampling voltage division circuit is a three-port network, one end of the voltage signal sampling voltage division circuit is used as the input end of the compensation circuit and is used for receiving a voltage sampling signal, one end of the voltage signal sampling voltage division circuit is grounded, and the other end of the voltage signal sampling voltage division circuit is used as the output end of the voltage signal sampling voltage division circuit and is connected with the sampling signal amplification circuit; the sampling signal amplifying circuit is a three-port network, one end of the sampling signal amplifying circuit is a power supply end of the sampling signal amplifying circuit, one end of the sampling signal amplifying circuit is connected with the voltage signal sampling voltage division circuit, and the other end of the sampling signal amplifying circuit is used as an output end of the sampling signal amplifying circuit and is connected with the signal regulating circuit; the signal regulating circuit is a two-port network, one end of the signal regulating circuit is connected with the sampling signal amplifying circuit, and the other end of the signal regulating circuit is used as the output end of the compensating circuit; wherein,
the voltage signal sampling voltage division circuit is used for dividing an input voltage sampling signal into a low voltage signal which is in direct proportion to the input voltage and is used by the sampling signal amplification circuit;
the sampling signal amplifying circuit is used for converting a voltage signal generated by the voltage signal sampling voltage division circuit into a current signal and amplifying the current signal;
and the signal adjusting circuit is used for adjusting the current signal amplified by the sampling signal amplifying circuit, outputting a compensation current signal through the output end of the compensation circuit and compensating the current signal on the sampling resistor Rcs of the power supply.
2. The overcurrent protection compensation circuit of claim 1, wherein: the voltage signal sampling voltage division circuit is mainly a voltage division circuit composed of resistors and comprises a resistor R1, a resistor R2, a resistor R3 and a capacitor C1; the sampling signal amplifying circuit is an amplifying circuit formed by NPN type triode and comprises a triode Q1; the signal regulating circuit is a voltage regulating circuit consisting of resistors and comprises a resistor R4; the specific connection relation is that one end of a resistor R1 is led out to be an input end of a compensation circuit for receiving a sampling signal, the other end of a resistor R1 is sequentially connected with a resistor R2 and a resistor R3 in series and then grounded, and a voltage division point is formed by the series connection point of the resistor R2 and the resistor R3; the capacitor C1 is connected in parallel with two ends of the resistor R3; the base electrode of the triode Q1 is connected with a voltage division point, the collector electrode of the triode Q1 is led out to be a power supply end, the emitter electrode of the triode Q1 is connected with one end of the resistor R4, and the other end of the resistor R4 is led out to be the output end of the compensation circuit.
3. The overcurrent protection compensation circuit of claim 1 or claim 2, wherein: the voltage sampling signal received by the input end of the compensation circuit is from the power bus voltage Vbus or from the direct current voltage VCC rectified by the power auxiliary winding.
4. The overcurrent protection compensation circuit of claim 1 or claim 2, wherein: the power supply of the power supply end of the sampling signal amplifying circuit is from direct current voltage VCC rectified by the power supply auxiliary winding or reference voltage Vref of the power supply control chip.
5. The utility model provides an overcurrent protection's compensating circuit which characterized in that: comprises a voltage signal sampling voltage-dividing circuit, a sampling signal amplifying circuit and a signal regulating circuit,
the voltage signal sampling voltage division circuit comprises a resistor R1, a resistor R2, a resistor R3 and a capacitor C1, the sampling signal amplifying circuit comprises a triode Q1, the signal adjusting circuit comprises a resistor R4, the specific connection relationship is that one end of a resistor R1 is led out to be the input end of a compensation circuit and used for receiving sampling signals, the other end of the resistor R1 is sequentially connected with the resistor R2 and the resistor R3 in series and then grounded, and a voltage division point is formed by the series connection point of the resistor R2 and the resistor R3; the capacitor C1 is connected in parallel with two ends of the resistor R3; the base electrode of the triode Q1 is connected with a voltage division point, the collector electrode of the triode Q1 is led out to be a power supply end, the emitter electrode of the triode Q1 is connected with one end of the resistor R4, and the other end of the resistor R4 is led out to be the output end of the compensation circuit.
6. The overcurrent protection compensation circuit of claim 5, wherein: the input end of the compensation circuit is connected with the power bus voltage Vbus or the direct current voltage VCC rectified by the power auxiliary winding.
7. The overcurrent protection compensation circuit of claim 5, wherein: and the power supply end of the sampling signal amplifying circuit is connected with the direct current voltage VCC rectified by the power supply auxiliary winding or the reference voltage Vref of the power supply control chip.
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| CN109039042A (en) * | 2018-08-03 | 2018-12-18 | 广州金升阳科技有限公司 | The compensation circuit of overcurrent protection |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109039042A (en) * | 2018-08-03 | 2018-12-18 | 广州金升阳科技有限公司 | The compensation circuit of overcurrent protection |
| CN109039042B (en) * | 2018-08-03 | 2023-11-17 | 广州金升阳科技有限公司 | Compensation circuit for overcurrent protection |
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Granted publication date: 20190301 Effective date of abandoning: 20231117 |