CN2865135Y - Short-circuit protection circuit for power amplifier output - Google Patents
Short-circuit protection circuit for power amplifier output Download PDFInfo
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- CN2865135Y CN2865135Y CN 200520059766 CN200520059766U CN2865135Y CN 2865135 Y CN2865135 Y CN 2865135Y CN 200520059766 CN200520059766 CN 200520059766 CN 200520059766 U CN200520059766 U CN 200520059766U CN 2865135 Y CN2865135 Y CN 2865135Y
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- power amplifier
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- amplifier output
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Abstract
A protection circuit against short-circuit of power amplifier output is provided, mainly comprising a power amplifier output signal detection and current detection circuit, a judging circuit, and a protection control circuit, wherein, the electrical signal output end of the power amplifier output signal detection and current detection circuit is connected to the electric signal input end of the judging circuit, and the electrical signal output end of the judging circuit is connected to the electric signal input end of the protection control circuit. Compared to the prior art, the utility model doesn't produce any false action and can protect the power amplifier against damage in case of short circuit.
Description
Technical field:
The utility model relates to a kind of short-circuit protection circuit.
Background technology:
The power amplifier output short circuit protection circuit is the pith of modern power amplifier design, because output short circuit meeting causes that the electric current of power amplifier sharply increases suddenly, will burn out power amplifier in the several seconds when power amplifier is worked.The generation of short circuit has artificial factor, and outside factor is also arranged, due to biting as the wearing and tearing of audio amplifier line or insect pest.Particularly professional power amplifier costs an arm and a leg, and the environment for use complexity is provided with short-circuit protection circuit and seems extremely important.
When the power amplifier no signal was exported, the electric current of power amplifier can not increase during the output short circuit, can not burn out power amplifier yet.But when power amplifier has signal output (during work), be short-circuited as output, at this moment, the output load of power amplifier is zero, and the power amplifier electric current sharply increases, and certainly, when signal output was big more, the increase of power amplifier output current was also big more during short circuit.Traditional protection control circuit detects the power amplifier output current and starts the protection control circuit.But this circuit has significant disadvantages; the value of starting to control electric current exactly is difficult to determine that when starting to control current value Ding Detai hour, the protection control circuit is easy to generate misoperation; sometimes instantaneous big dynamic concert makes the electric current moment increase of power amplifier, just can make the protection control circuit produce misoperation.Particularly Xian Dai music all is to pursue greatly dynamically, and contradiction is just more outstanding.And when starting to control current value design when big; though during big dynamic music; the protection control circuit can not produce misoperation; but when the power amplifier output signal hour; short circuit output power amplifier electric current at this moment increases; but do not reach the value of starting to control electric current, and the protection control circuit has just lost protective effect, and power amplifier also may burn out in a few minutes.
, there are two big features in power amplifier when work during output short-circuit, the electric current increase of first power amplifier, and it two is output no signals of power amplifier.Traditional protective circuit utilizes the one feature to come design circuit.As shown in Figure 1; T1; T2 is the power output tube of power amplifier; T3 detects the triode that electric current plays control; when power amplifier is short-circuited; the electric current of efferent duct increases, and the pressure drop of R1 also can increase, when increasing to a certain value; T3 pipe meeting conducting; thereby the action of deactivation protection control circuit is adjusted R4 and can be adjusted the size (sensitivity) of starting to control electric current, obviously; when starting to control current value design hour; big music dynamically can make circuit produce misoperation, and the user also can influence the sensitivity of starting to control when using the audio amplifier of different impedances, and starts to control the current value design when big; can lose the meaning of protection again, the shortcoming of Here it is traditional short-circuit protection control circuit.
Summary of the invention:
Goal of the invention of the present utility model is to provide a kind of neither can produce misoperation, simultaneously, and the power amplifier output short circuit protection circuit that can protect power amplifier to avoid destroying again during short circuit.
The utility model is to realize like this; mainly constitute by the detection of power amplifier output signal, current detecting, decision circuitry, protection control circuit; the power amplifier output signal detects, the electrical signal of current detecting links to each other with the electric signal input end of decision circuitry, and the decision circuitry electrical signal links to each other with the electric signal input end of protection control circuit.During work; when current detecting detects big electric current; send the signal of telecommunication to decision circuitry; simultaneously; when if the power amplifier output signal detects and not to detect the power amplifier output signal of telecommunication output is arranged; decision circuitry is made the short circuit judgement, and sends the signal of telecommunication to the protection control circuit, protects power amplifier to avoid the destruction of short circuit by protection control circuit (contactor of opening/closing as the control power supply disconnects power supply).Otherwise, if the power amplifier output signal detects the power amplifier output in signal of telecommunication when output, being arranged, decision circuitry just can not moved, and protects control circuit can not be touched.Because during power amplifier work; output short-circuit has two big features; the electric current of first power amplifier increases; it two is output no signals of power amplifier, and the double check circuit has enough sensitivity and don't can produce misoperation, that is to say circuit accurately decision circuitry be in short circuit and start the protection control circuit; and start to control electric current and can design lessly; make circuit that enough sensitivity is arranged, because second detection arranged, circuit produces misoperation never.
Compared with the prior art the utility model has neither and can produce misoperation, simultaneously, and the advantage that can protect power amplifier to avoid destroying again during short circuit.
Description of drawings:
Fig. 1 is the circuit diagram of prior art;
Fig. 2 is the circuit diagram of embodiment 1;
Fig. 3 is the circuit diagram of embodiment 2.
Embodiment:
Now in conjunction with the accompanying drawings and embodiments the utility model is described in further detail:
Embodiment 1: as shown in Figure 2; the utility model mainly detects 1 by the power amplifier output signal; current detecting 2; decision circuitry 3; protection control circuit 4 constitutes; decision circuitry 3 is by triode T4; T5; resistance R 9; R10; pressure limiting diode D2; D3 constitutes; triode T4 base stage links to each other with current detecting 2 by resistance R 8; collector electrode links to each other with 12 volts of DC power supply by resistance R 9; emitter is respectively by pressure limiting diode D2; D3 links to each other and links to each other with the collector electrode of triode T5 by resistance R 10 with protection control circuit 4; the base stage of triode T5 detects 1 with the power amplifier output signal and links to each other; grounded emitter; current detecting 2 is by triode T3; resistance R 3; R4; R5; R6; R7 constitutes; the emitter of triode T3 links to each other with the input of power amplifier positive supply; collector electrode and resistance R 6; R7 serial connection back ground connection; resistance R 3 is connected between input of power amplifier positive supply and the input of power amplifier power tube positive supply; resistance R 4; R5 one end is connected on the base stage of triode T3; the other end is connected to resistance R 3 two ends, and the power amplifier output signal detects 1 by being connected power amplifier two power tube T1; the resistance R 1 of connecting between T2; resistance R 11 between R2 constitutes.During work, when the power amplifier no signal, T4, all not conductings of T5, power amplifier output signal detection 1, current detecting 2 equal no signals outputs, the emitter of the triode T4 of decision circuitry 3 is less than D2, the required voltage of D3 conducting, and decision circuitry 3 no signals output to protection control circuit 4; When big dynamically music, because big electric current is arranged, R3 on the current detecting 2 produces big pressure drop, the T3 conducting, and current detecting 2 has signal to output on the decision circuitry 3, T4 conducting on the decision circuitry 3, if power amplifier output does not have short circuit, the power amplifier output signal detects 1 has signal to output to decision circuitry 3, the triode T5 conducting on the decision circuitry 3, the emitter of the triode T4 of decision circuitry 3 is less than D2, the required voltage of D3 conducting, and decision circuitry 3 no signals output to protection control circuit 4; If during power amplifier work; the power amplifier output short-circuit; the electric current of power amplifier increases, and current detecting 2 has signal output, T4 conducting; the power amplifier output signal detects 1 does not have signal to output to decision circuitry 3; not conducting of triode T5 on the decision circuitry 3, the emitter voltage of the triode T4 of decision circuitry 3 are greater than D2, the required voltage of D3 conducting, and decision circuitry 3 has signal to output to protection control circuit 4; protection control circuit 4 starts, and the protection power amplifier is avoided short circuit and burnt out.Here, R4 is an adjustable resistance, by regulating the resistance of R4, regulates the sensitivity of starting to control.The two ends of detecting 1 resistance R 11 in the power amplifier output signal are serially connected with capacitor C 1, diode D1 respectively, be provided with the capacitor C that plays filter action 2 that links to each other with ground in diode D1 back, the effect of C1 is to guarantee that the signal that receives is an audio signal, and the effect of C2 is to guarantee that outputing to decision circuitry 3 is stable signals.Connect an adjustable resistance R12 between the base stage of triode T5, emitter, the effect of R12 is the sensitivity of regulating decision circuitry 3.
Embodiment two: as shown in Figure 3, present embodiment is on the basis of embodiment 1, current detecting 2 is by the resistance R 12 on the first order power tube T1 emitter that is connected power amplifier two power tubes, and R13, R14, R6, R7, R8, triode T7, T6 constitutes, the R12 other end is connected on the base stage of triode T7, resistance R 13 1 ends are connected on the base stage of triode T5, the other end is connected the power amplifier output, the collector electrode of triode T7 is connected with power supply by resistance R 14, emitter links to each other with the power amplifier output, the base stage of triode T6 links to each other with the collector electrode of T7, emitter links to each other with the 12V power supply, collector electrode is by resistance R 6, R7 ground connection, resistance R 8 one ends are connected the R6 of series connection, between R7, an end links to each other with the base stage of the triode T4 of decision circuitry 3.
Claims (7)
1, a kind of power amplifier output short circuit protection circuit; it is characterized in that mainly constituting by the detection of power amplifier output signal, current detecting, decision circuitry, protection control circuit; the power amplifier output signal detects, the electrical signal of current detecting links to each other with the electric signal input end of decision circuitry, and the decision circuitry electrical signal links to each other with the electric signal input end of protection control circuit.
2; power amplifier output short circuit protection circuit according to claim 1; it is characterized in that decision circuitry (3) is by triode T4; T5; resistance R 9; R10; pressure limiting diode D2; D3 constitutes; triode T4 base stage links to each other with current detecting (2) by resistance R 8; collector electrode links to each other with 12 volts of DC power supply by resistance R 9; emitter is respectively by pressure limiting diode D2; D3 links to each other with protection control circuit (4) and links to each other with the collector electrode of triode T5 by resistance R 10; the base stage of triode T5 detects with the power amplifier output signal and links to each other; grounded emitter, power amplifier output signal detect by the resistance R 11 that is connected the output of power amplifier signal and constitute.
3, power amplifier output short circuit protection circuit according to claim 2; the two ends that it is characterized in that the resistance R 11 that detects in the power amplifier output signal are serially connected with capacitor C 1, diode D1 respectively, are provided with the capacitor C that plays filter action 2 that links to each other with ground in diode D1 back.
4, power amplifier output short circuit protection circuit according to claim 2 is characterized in that connecting between the base stage, emitter at triode T5 an adjustable resistance R12.
5, power amplifier output short circuit protection circuit according to claim 1 and 2; it is characterized in that current detecting is made of triode T3, resistance R 3, R4, R5, R6, R7; the emitter of triode T3 links to each other with the input of power amplifier positive supply; collector electrode is connected in series back ground connection with resistance R 6, R7; resistance R 3 is connected between input of power amplifier positive supply and the input of power amplifier power tube positive supply; resistance R 4, R5 one end are connected on the base stage of triode T3, and the other end is connected to resistance R 3 two ends.
6, power amplifier output short circuit protection circuit according to claim 5 is characterized in that resistance R 4 is adjustable resistance.
7; power amplifier output short circuit protection circuit according to claim 1 and 2; it is characterized in that current detecting is by the resistance R 12 on the first order power tube T1 emitter that is connected power amplifier two power tubes; and R13; R14; R6; R7; R8; triode T7; T6 constitutes; resistance R 12 other ends are connected on the base stage of triode T7; resistance R 13 1 ends are connected on the base stage of triode T7; the other end is connected the power amplifier output; the collector electrode of triode T7 is connected with power supply by resistance R 14; emitter links to each other with the power amplifier output; the base stage of triode T6 links to each other with the collector electrode of T7; emitter links to each other with the 12V power supply; collector electrode is by resistance R 6; R7 ground connection; resistance R 8 one ends are connected the R6 of series connection; between R7, an end links to each other with the base stage of the triode T4 of decision circuitry (3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520059766 CN2865135Y (en) | 2005-06-07 | 2005-06-07 | Short-circuit protection circuit for power amplifier output |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520059766 CN2865135Y (en) | 2005-06-07 | 2005-06-07 | Short-circuit protection circuit for power amplifier output |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2865135Y true CN2865135Y (en) | 2007-01-31 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200520059766 Expired - Fee Related CN2865135Y (en) | 2005-06-07 | 2005-06-07 | Short-circuit protection circuit for power amplifier output |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2865135Y (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976825A (en) * | 2010-10-29 | 2011-02-16 | 中山美加音响发展有限公司 | Short circuit protection circuit for audio power amplifier |
| CN102412792A (en) * | 2010-09-22 | 2012-04-11 | Oki半导体株式会社 | Signal amplifier, bridge connection signal amplifier, signal output device and latch-up prevention method |
| CN103217615A (en) * | 2013-03-27 | 2013-07-24 | 上海贝岭股份有限公司 | Output short-circuit detection circuit |
| CN105932973A (en) * | 2016-04-16 | 2016-09-07 | 合肥博雷电气有限公司 | Control protection circuit of solid state microwave power amplifier |
-
2005
- 2005-06-07 CN CN 200520059766 patent/CN2865135Y/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412792A (en) * | 2010-09-22 | 2012-04-11 | Oki半导体株式会社 | Signal amplifier, bridge connection signal amplifier, signal output device and latch-up prevention method |
| CN102412792B (en) * | 2010-09-22 | 2016-01-06 | 拉碧斯半导体株式会社 | Signal amplifying apparatus, signal output apparatus and latch-up preventing method |
| CN101976825A (en) * | 2010-10-29 | 2011-02-16 | 中山美加音响发展有限公司 | Short circuit protection circuit for audio power amplifier |
| CN101976825B (en) * | 2010-10-29 | 2013-11-06 | 广东美加音响发展有限公司 | Short circuit protection circuit for audio power amplifier |
| CN103217615A (en) * | 2013-03-27 | 2013-07-24 | 上海贝岭股份有限公司 | Output short-circuit detection circuit |
| CN103217615B (en) * | 2013-03-27 | 2015-03-25 | 上海贝岭股份有限公司 | Output short-circuit detection circuit |
| CN105932973A (en) * | 2016-04-16 | 2016-09-07 | 合肥博雷电气有限公司 | Control protection circuit of solid state microwave power amplifier |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20070131 Termination date: 20100607 |