CN204559091U - For the input short protective circuit of PWM type audio frequency power amplifier - Google Patents
For the input short protective circuit of PWM type audio frequency power amplifier Download PDFInfo
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- CN204559091U CN204559091U CN201520230367.2U CN201520230367U CN204559091U CN 204559091 U CN204559091 U CN 204559091U CN 201520230367 U CN201520230367 U CN 201520230367U CN 204559091 U CN204559091 U CN 204559091U
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Abstract
The utility model discloses a kind of input short protective circuit for PWM type audio frequency power amplifier, this circuit comprises input pin voltage detecting circuit, detects the voltage of the input pin of audio frequency power amplifier; Pwm signal output circuit, exports the first pwm signal and the second pwm signal; Exporting PWM duty ratio difference detecting circuit, when receiving enable signal, detecting the difference of the duty ratio of the first pwm signal and the second pwm signal; Input short guard signal produces circuit; when receiving enable signal and exceeding short-circuit protection early warning duration when the duration that the difference of the duty ratio of the first pwm signal and described second pwm signal reaches default maximum duty cycle difference signal, export PWM duty cycle control signal to pwm signal output circuit to control the difference of the duty ratio of the first pwm signal and the second pwm signal.The utility model can prevent the infringement of power output loss or audio frequency power amplifier and load.
Description
Technical field
The utility model relates to integrated circuit fields, particularly a kind of input short protective circuit for PWM type audio frequency power amplifier.
Background technology
The audio-frequency power amplifier (abbreviation audio frequency power amplifier) of switching mode middle low power (power output is 5 watts to 50 watts) is widely used in consumer electronics product, and PWM (i.e. pulse width modulation) is the primary modulation mode of audio frequency power amplifier.Audio frequency power amplifier is as power stage type device, and its inside is generally integrated with multiple protection mechanism, and as overheat protector, overcurrent protection and overvoltage protection etc., the top priority of these protective circuits is the safety of protection audio frequency power amplifier self.General audio frequency power amplifier is when applying, and its input can connect capacitance with the infringement of the power output loss eliminated input signal DC voltage component and cause or audio frequency power amplifier itself and load (loudspeaker).If the capacitance of audio frequency power amplifier input (being called for short input capacitance) damage or its input pin direct short-circuit are on VDD-to-VSS, the infringement of power output loss or audio frequency power amplifier itself and load will be caused.
In prior art; normally realize the defencive function to audio frequency power amplifier by overcurrent protection or overheat protector; but in these two kinds of protected modes; it is generally fixing for crossing flow point and crossing warm spot; and larger deviation can be there is with technique or applied environment; thus easily cause the false triggering of audio frequency power amplifier protection mechanism or the inefficacy of protection mechanism; if and to make flow point and cross warm spot can change; then can increase the design complexities of protective circuit; and the more multiaspect taking audio frequency power amplifier chip is amassed, and then increases cost.
Utility model content
Main purpose of the present utility model be prevent the input capacitance when PWM type audio frequency power amplifier from damaging or in input pin direct short-circuit to VDD-to-VSS time and the infringement of the power output loss that causes or this audio frequency power amplifier itself and load.
For achieving the above object, the utility model provides a kind of input short protective circuit for PWM type audio frequency power amplifier, and the described input short protective circuit for PWM type audio frequency power amplifier comprises input pin voltage detecting circuit, maximum duty cycle difference produces circuit, output PWM duty ratio difference detecting circuit, input short guard signal produce circuit and pwm signal output circuit; Wherein,
Described input pin voltage detecting circuit, the voltage of the input pin of described PWM type audio frequency power amplifier is detected, when the voltage of described input pin reaches predetermined threshold value voltage, export an enable signal and produce circuit to described output PWM duty ratio difference detecting circuit and described input short guard signal;
Described maximum duty cycle difference produces circuit, produces a maximum duty cycle difference signal preset;
Described pwm signal output circuit, exports the first pwm signal and the second pwm signal;
Described output PWM duty ratio difference detecting circuit, when receiving described enable signal, detects the difference of the duty ratio of described first pwm signal and described second pwm signal;
Described input short guard signal produces circuit, receiving described enable signal, and when the duration that the difference of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal exceedes default short-circuit protection early warning duration, then judge that short circuit appears in the input pin of described PWM type audio frequency power amplifier, and export the control end of a PWM duty cycle control signal to described pwm signal output circuit to control the difference of the duty ratio of described first pwm signal and described second pwm signal, reach the input short protection object to described PWM type audio frequency power amplifier.
Preferably; described input short guard signal produces circuit and is receiving described enable signal; and when the duration that the difference of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal exceedes default short-circuit protection early warning duration; export a short circuit alarm signal, occur short circuit with the input pin of PWM type audio frequency power amplifier described in reminding user.
Preferably, the test side of described input pin voltage detecting circuit is connected with the input pin of described PWM type audio frequency power amplifier, and the Enable Pin that the output of described input pin voltage detecting circuit produces circuit with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit is respectively connected; The test side of described output PWM duty ratio difference detecting circuit is connected with the output of described pwm signal output circuit, and the output of described output PWM duty ratio difference detecting circuit is connected with the first input end that described input short guard signal produces circuit; The output that described maximum duty cycle difference produces circuit is connected with the second input that described input short guard signal produces circuit; The output that described input short guard signal produces circuit is connected with the control end of described pwm signal output circuit.
Preferably, described maximum duty cycle difference generation circuit comprises triangular signal generation circuit, the first reference voltage generating circuit, the first voltage comparator and the first sequential logical circuit; Wherein,
The output that first input end and the described triangular signal of described first voltage comparator produce circuit is connected; second input of described first voltage comparator is connected with the output of described first reference voltage generating circuit, and the second input that the output of described first voltage comparator produces circuit through described first sequential logical circuit and described input short guard signal is connected.
Preferably, described input pin voltage detecting circuit comprises filter circuit, the second reference voltage generating circuit, the second voltage comparator and the second sequential logical circuit; Wherein,
The first input end of described second voltage comparator is connected through the input pin of described filter circuit with described PWM type audio frequency power amplifier; second input of described second voltage comparator is connected with the output of described second reference voltage generating circuit, and the Enable Pin that the output of described second voltage comparator produces circuit with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit respectively through described second sequential logical circuit is connected.
Preferably, described filter circuit comprises the first resistance and the first electric capacity; Wherein,
The first end of described first resistance is connected with the input pin of described PWM type audio frequency power amplifier, and the second end of described first resistance is connected with the first input end of described second voltage comparator; The first end of described first electric capacity is connected with the first input end of described second voltage comparator, the second end ground connection of described first electric capacity.
Preferably, described input short guard signal generation circuit comprises operating voltage input, the 3rd reference voltage generating circuit, the first reference current source, the second reference current source, tertiary voltage comparator, duration testing circuit, PMOS, NMOS tube and charge-discharge circuit; Wherein,
The grid of described PMOS is connected with the described output exporting PWM duty ratio difference detecting circuit, and the source electrode of described PMOS is connected with the negative pole of described first reference current source, and the positive pole of described first reference current source is connected with described operating voltage input; The drain electrode of described PMOS is connected with described charge-discharge circuit; The drain electrode of described NMOS tube is connected with described charge-discharge circuit, the output that grid and the described maximum duty cycle difference of described NMOS tube produce circuit is connected, the source electrode of described NMOS tube is connected with the positive pole of described second reference current source, the minus earth of described second reference current source; The first input end of described tertiary voltage comparator is connected with the drain electrode of described NMOS tube, second input of described tertiary voltage comparator is connected with the output of described 3rd reference voltage generating circuit, the Enable Pin of described tertiary voltage comparator is connected with the output of described input pin voltage detecting circuit, and the output of described tertiary voltage comparator is connected through the control end of described duration testing circuit with described pwm signal output circuit.
Preferably, described charge-discharge circuit comprises the second resistance and the second electric capacity; Wherein,
The first end of described second resistance is connected with the drain electrode of described PMOS, and the second end of described second resistance is connected with the first input end of described tertiary voltage comparator
;the first end of described second electric capacity is connected with the second end of described second resistance, the second end ground connection of described second electric capacity.
The input short protective circuit for PWM type audio frequency power amplifier that the utility model provides, comprises input pin voltage detecting circuit, maximum duty cycle difference generation circuit, exports PWM duty ratio difference detecting circuit, input short guard signal generation circuit and pwm signal output circuit, described input pin voltage detecting circuit, voltage for the input pin to described PWM type audio frequency power amplifier detects, when the voltage of described input pin reaches predetermined threshold value voltage, export an enable signal and produce circuit to described output PWM duty ratio difference detecting circuit and described input short guard signal, described maximum duty cycle difference produces circuit, for generation of the maximum duty cycle difference signal that presets, described pwm signal output circuit, for exporting the first pwm signal and the second pwm signal, described output PWM duty ratio difference detecting circuit, when receiving described enable signal, detects the difference of the duty ratio of described first pwm signal and described second pwm signal, described input short guard signal produces circuit, receiving described enable signal, and when the duration that the difference of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal exceedes default short-circuit protection early warning duration, then judge that short circuit appears in the input pin of described PWM type audio frequency power amplifier, and export the control end of a PWM duty cycle control signal to described pwm signal output circuit to control the difference of the duty ratio of described first pwm signal and described second pwm signal, reach the input short protection object to described PWM type audio frequency power amplifier.The utility model can prevent the input capacitance when PWM type audio frequency power amplifier from damaging or in input pin direct short-circuit to VDD-to-VSS time and the infringement of the power output loss that causes or this audio frequency power amplifier itself and load; Meanwhile, the utility model also has that circuit structure is simple, cost is low and the advantage of easy realization.
Accompanying drawing explanation
Fig. 1 is the modular structure schematic diagram of the utility model for input short protective circuit one embodiment of PWM type audio frequency power amplifier;
Fig. 2 is the electrical block diagram that in Fig. 1, maximum duty cycle difference produces circuit one embodiment;
Fig. 3 is the electrical block diagram of input pin voltage detecting circuit one embodiment in Fig. 1;
Fig. 4 exports the circuit connection structure schematic diagram that PWM duty ratio difference detecting circuit and input short guard signal produce circuit one embodiment in Fig. 1.
The realization of the utility model object, functional characteristics and advantage will in conjunction with the embodiments, are described further with reference to accompanying drawing.
Embodiment
Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
The utility model provides a kind of input short protective circuit for PWM type audio frequency power amplifier.
Reference Fig. 1, Fig. 1 are the modular structure schematic diagram of the utility model for input short protective circuit one embodiment of PWM type audio frequency power amplifier.
In the present embodiment, this input short protective circuit being used for PWM type audio frequency power amplifier comprises maximum duty cycle difference and produces circuit 101, input pin voltage detecting circuit 102, output PWM duty ratio difference detecting circuit 103, input short guard signal generation circuit 104 and pwm signal output circuit 105.
Wherein, described maximum duty cycle difference produces circuit 101, for generation of the maximum duty cycle difference signal DCM that presets;
Described input pin voltage detecting circuit 102, voltage VIN for the input pin to PWM type audio frequency power amplifier (not shown) detects, when the voltage VIN of described input pin reaches predetermined threshold value voltage, export an enable signal EN produces circuit 104 Enable Pin to the Enable Pin of described output PWM duty ratio difference detecting circuit 103 and described input short guard signal, to control described outputs PWM duty ratio difference detecting circuit 103 and described input short guard signal generation circuit 104 is started working;
Described pwm signal output circuit 105, for exporting the first pwm signal and the second pwm signal;
Described output PWM duty ratio difference detecting circuit 103, when receiving the described enable signal EN that described input pin voltage detecting circuit 102 exports, the difference VDC of described first pwm signal export described pwm signal output circuit 105 and the duty ratio of described second pwm signal detects;
Described input short guard signal produces circuit 104, receiving the described enable signal EN of described input pin voltage detecting circuit 102 output, and when the duration that the difference VDC of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal DCM exceedes default short-circuit protection early warning duration, then judge that short circuit appears in the input pin of described PWM type audio frequency power amplifier, and export the control end of a PWM duty cycle control signal VPWM to described pwm signal output circuit 105 with the difference of the duty ratio of described first pwm signal and described second pwm signal that control the output of described pwm signal output circuit 105, to reach the input short protection object to PWM type audio frequency power amplifier.
Further; in the present embodiment; described input short guard signal produces circuit also at the described enable signal EN receiving the output of described input pin voltage detecting circuit 102; and when the duration that the difference VDC of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal DCM exceedes default short-circuit protection early warning duration; export a short circuit alarm signal FAULT; there is short circuit with the input pin of PWM type audio frequency power amplifier described in reminding user, facilitate user to check short trouble.
Particularly, in the present embodiment, the test side of described input pin voltage detecting circuit 102 is connected with the input pin of PWM type audio frequency power amplifier, and the Enable Pin that the output of described input pin voltage detecting circuit 102 produces circuit 104 with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit 103 is respectively connected; The test side of described output PWM duty ratio difference detecting circuit 103 is connected with the output of described pwm signal output circuit 105, and the output of described output PWM duty ratio difference detecting circuit 103 is connected with the first input end that described input short guard signal produces circuit 104; The output that described maximum duty cycle difference produces circuit 101 is connected with the second input that described input short guard signal produces circuit 104; The output that described input short guard signal produces circuit 104 is connected with the control end of described pwm signal output circuit 105; The output of described pwm signal output circuit 105 is also connected with load 200.
Fig. 2 is the electrical block diagram that in Fig. 1, maximum duty cycle difference produces circuit one embodiment.
See figures.1.and.2 in the lump, in the present embodiment, described maximum duty cycle difference produces circuit 101 and comprises triangular signal generation circuit 1011, first reference voltage generating circuit 1012, first voltage comparator 1013 and the first sequential logical circuit 1014.
Particularly; the first input end of described first voltage comparator 1013 is connected with the output that described triangular signal produces circuit 1011; second input of described first voltage comparator 1013 is connected with the output of described first reference voltage generating circuit 1012, and the second input that the output of described first voltage comparator 1013 produces circuit 104 through described first sequential logical circuit 1014 and described input short guard signal is connected.
In the present embodiment; described triangular signal is produced triangular signal that circuit 1011 produces and the first reference voltage V REF1 that described first reference voltage generating circuit 1012 produces and to compare and after the sequencing control process of described first sequential logical circuit 1014 by described first voltage comparator 1013; produce described maximum duty cycle difference signal DCM, and described maximum duty cycle difference signal DCM is exported to described input short guard signal generation circuit 104.
Fig. 3 is the electrical block diagram of input pin voltage detecting circuit one embodiment in Fig. 1.
In the lump with reference to Fig. 1 and Fig. 3, in the present embodiment, described input pin voltage detecting circuit 102 comprises filter circuit 1021, second reference voltage generating circuit 1022, second voltage comparator 1023 and the second sequential logical circuit 1024.
Particularly; the first input end of described second voltage comparator 1023 is connected through the input pin of described filter circuit 1021 with PWM type audio frequency power amplifier; second input of described second voltage comparator 1023 is connected with the output of described second reference voltage generating circuit 1022, and the Enable Pin that the output of described second voltage comparator 1023 produces circuit 104 with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit 103 respectively through described second sequential logical circuit 1024 is connected.
In the present embodiment, described filter circuit 1021 comprises the first resistance R1 and the first electric capacity C1.Particularly, the first end of described first resistance R1 is connected with the input pin of described PWM type audio frequency power amplifier, and second end of described first resistance R1 is connected with the first input end of described second voltage comparator 1023; The first end of described first electric capacity C1 is connected with the first input end of described second voltage comparator 1023, the second end ground connection GND of described first electric capacity C1.
In the present embodiment; the second reference voltage V REF2 that the voltage VIN of the input pin of the PWM type audio frequency power amplifier after the filtering process of described filter circuit 1021 and described second reference voltage generating circuit 1022 produce compares and after the sequencing control process of described second sequential logical circuit 1024 by described second voltage comparator 1023, produces and produces for controlling described output PWM duty ratio difference detecting circuit 103 and described input short guard signal the enable signal EN that circuit 104 starts working.In the present embodiment, the described enable signal EN that described input pin voltage detecting circuit 102 exports is used for the first heavy decision mechanism of the input short protective circuit execution input short protection of PWM type audio frequency power amplifier as the present embodiment, namely when described input pin voltage detecting circuit 102 detect the voltage VIN of the input pin of PWM type audio frequency power amplifier reach described second reference voltage generating circuit 1022 produce the second reference voltage V REF2 time (in the present embodiment, the second reference voltage V REF2 that described second reference voltage generating circuit 1022 produces is above-mentioned predetermined threshold value voltage), export described enable signal EN, and described enable signal EN is exported to the described Enable Pin of output PWM duty ratio difference detecting circuit 103 and the Enable Pin of described input short guard signal generation circuit 104, produce circuit 104 start working to control described output PWM duty ratio difference detecting circuit 103 and described input short guard signal, thus open the input short protective circuit execution input short protection second heavy decision mechanism of the present embodiment for PWM type audio frequency power amplifier.
Fig. 4 exports the circuit connection structure schematic diagram that PWM duty ratio difference detecting circuit and input short guard signal produce circuit one embodiment in Fig. 1.
In the lump with reference to Fig. 1 and Fig. 4; in the present embodiment, described input short guard signal produces circuit 104 and comprises operating voltage input VCC, charge-discharge circuit 1041, the 3rd reference voltage generating circuit 1042, tertiary voltage comparator 1043, duration testing circuit 1044, first reference current source A, the second reference current source B, PMOS P1, NMOS tube N1.
Particularly, the Enable Pin of described output PWM duty ratio difference detecting circuit 103 is connected with the output of described input pin voltage detecting circuit 102, the test side of described output PWM duty ratio difference detecting circuit 103 is connected with the output of described pwm signal output circuit 105 (namely the difference VDC of the duty ratio of described first pwm signal that described pwm signal output circuit 105 exports and described second pwm signal is detected in the test side of the described PWM of output duty ratio difference detecting circuit 103), the output of described output PWM duty ratio difference detecting circuit 103 is connected with the first input end that described input short guard signal produces circuit 104 (namely the described PWM of output duty ratio difference detecting circuit 103 exports the difference VDC of the described duty ratio detected to first input end that described input short guard signal produces circuit 104),
In the present embodiment, the grid (corresponding to the first input end that described input short guard signal produces circuit 104) of described PMOS P1 is connected with the described output exporting PWM duty ratio difference detecting circuit 103, the source electrode of described PMOS P1 is connected with the negative pole of described first reference current source A, and the positive pole of described first reference current source A is connected with described operating voltage input VCC; The drain electrode of described PMOS P1 is connected with described charge-discharge circuit 1041; The drain electrode of described NMOS tube N1 is connected with described charge-discharge circuit 1041, the output that the grid (corresponding to the second input that described input short guard signal produces circuit 104) of described NMOS tube N1 and described maximum duty cycle difference produce circuit 101 is connected (namely the grid of described NMOS tube N1 inputs the poor described maximum duty cycle difference signal DCM producing circuit 101 and produce of described maximum duty cycle), the source electrode of described NMOS tube N1 is connected with the positive pole of described second reference current source B, the minus earth of described second reference current source B; The first input end of described tertiary voltage comparator 1043 is connected with the drain electrode of described NMOS tube N1, second input of described tertiary voltage comparator 1043 is connected with the output of described 3rd reference voltage generating circuit 1042, the Enable Pin of described tertiary voltage comparator 1043 is connected with the output of described input pin voltage detecting circuit 102, and the output of described tertiary voltage comparator 1043 is connected through the control end of described duration testing circuit 1044 with described pwm signal output circuit 105.
In the present embodiment, described charge-discharge circuit 1041 comprises the second resistance R2 and the second electric capacity C2.Particularly, the first end of described second resistance R2 is connected with the drain electrode of described PMOS P1, and second end of described second resistance R2 is connected with the first input end of described tertiary voltage comparator 1043
;the first end of described second electric capacity C2 is connected with second end of described second resistance R2, the second end ground connection GND of described second electric capacity C2.
In the present embodiment, described output PWM duty ratio difference detecting circuit 103 and described input short guard signal produce described enable signal EN that circuit 104 produces by described input pin voltage detecting circuit 102 whether to control work.The difference VDC of the duty ratio of described first pwm signal that the described PWM of output duty ratio difference detecting circuit 103 detects and described second pwm signal controls described PMOS P1 and is charged to described charge-discharge circuit 1041 by the first reference current IREF1 of described first reference current source A output, and the described maximum duty cycle difference signal DCM that described maximum duty cycle difference generation circuit 101 produces controls described NMOS tube N1 and discharged to described charge-discharge circuit 1041 by the second reference current IREF2 of described second reference current source B output; then, voltage V1 on described charge-discharge circuit 1041 is led to the waveform signal that the 3rd reference voltage V REF3 produced with described 3rd reference voltage generating circuit 1042 compares rear generation one pulse width variations by described tertiary voltage comparator 1043, whether the duration finally detecting the low and high level of the waveform signal of described pulse width variations by described duration testing circuit 1044 reaches default short-circuit protection early warning duration, if the duration of the low and high level of the waveform signal of described pulse width variations reaches default short-circuit protection early warning duration, then judge that short-circuit conditions (namely the input capacitance of PWM type audio frequency power amplifier has likely occurred that damage or input pin direct short-circuit are on VDD-to-VSS) has appearred in the input pin of PWM type audio frequency power amplifier, and export the control end of a PWM duty cycle control signal VPWM to described pwm signal output circuit 105 to control the difference of the duty ratio of described first pwm signal and described second pwm signal, to realize the object turning off power output pipe in PWM type audio frequency power amplifier, thus prevent the infringement of power output loss or this audio frequency power amplifier itself and the load caused because of the short circuit of the input pin of PWM type audio frequency power amplifier.
The present embodiment is used for the input short protective circuit of PWM type audio frequency power amplifier while protection audio frequency power amplifier itself with load, the false triggering of protection mechanism that can effectively prevent PWM type audio frequency power amplifier from causing because of the difference of applied environment in actual application or the inefficacy of protection mechanism; And, the input short protective circuit that the present embodiment is used for PWM type audio frequency power amplifier outwards can also send short circuit alarm signal FAULT, short circuit has been there is, so that user checks short trouble with the input pin of reminding user PWM type audio frequency power amplifier; Meanwhile, the protection point that the present embodiment is used for the input short protective circuit of PWM type audio frequency power amplifier arranges versatile and flexible, and is convenient to the inside being integrated in audio frequency power amplifier chip; Meanwhile, the present embodiment also has that circuit structure is simple, cost is low and the advantage of easy realization.
These are only preferred embodiment of the present utility model; not thereby the scope of the claims of the present utility model is limited; every utilize the utility model specification and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present utility model.
Claims (8)
1. the input short protective circuit for PWM type audio frequency power amplifier, it is characterized in that, comprise input pin voltage detecting circuit, maximum duty cycle difference generation circuit, export PWM duty ratio difference detecting circuit, input short guard signal generation circuit and pwm signal output circuit; Wherein,
Described input pin voltage detecting circuit, the voltage of the input pin of described PWM type audio frequency power amplifier is detected, when the voltage of described input pin reaches predetermined threshold value voltage, export an enable signal and produce circuit to described output PWM duty ratio difference detecting circuit and described input short guard signal;
Described maximum duty cycle difference produces circuit, produces a maximum duty cycle difference signal preset;
Described pwm signal output circuit, exports the first pwm signal and the second pwm signal;
Described output PWM duty ratio difference detecting circuit, when receiving described enable signal, detects the difference of the duty ratio of described first pwm signal and described second pwm signal;
Described input short guard signal produces circuit, receiving described enable signal, and when the duration that the difference of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal exceedes default short-circuit protection early warning duration, then judge that short circuit appears in the input pin of described PWM type audio frequency power amplifier, and export the control end of a PWM duty cycle control signal to described pwm signal output circuit to control the difference of the duty ratio of described first pwm signal and described second pwm signal, reach the input short protection object to described PWM type audio frequency power amplifier.
2. the input short protective circuit for PWM type audio frequency power amplifier according to claim 1; it is characterized in that; described input short guard signal produces circuit and is receiving described enable signal; and when the duration that the difference of the duty ratio of described first pwm signal and described second pwm signal reaches default described maximum duty cycle difference signal exceedes default short-circuit protection early warning duration; export a short circuit alarm signal, described in reminding user there is short circuit in the input pin of PWM type audio frequency power amplifier.
3. the input short protective circuit for PWM type audio frequency power amplifier according to claim 1 and 2, it is characterized in that, the test side of described input pin voltage detecting circuit is connected with the input pin of described PWM type audio frequency power amplifier, and the Enable Pin that the output of described input pin voltage detecting circuit produces circuit with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit is respectively connected; The test side of described output PWM duty ratio difference detecting circuit is connected with the output of described pwm signal output circuit, and the output of described output PWM duty ratio difference detecting circuit is connected with the first input end that described input short guard signal produces circuit; The output that described maximum duty cycle difference produces circuit is connected with the second input that described input short guard signal produces circuit; The output that described input short guard signal produces circuit is connected with the control end of described pwm signal output circuit.
4. the input short protective circuit for PWM type audio frequency power amplifier according to claim 3, it is characterized in that, described maximum duty cycle difference produces circuit and comprises triangular signal generation circuit, the first reference voltage generating circuit, the first voltage comparator and the first sequential logical circuit; Wherein,
The output that first input end and the described triangular signal of described first voltage comparator produce circuit is connected; second input of described first voltage comparator is connected with the output of described first reference voltage generating circuit, and the second input that the output of described first voltage comparator produces circuit through described first sequential logical circuit and described input short guard signal is connected.
5. the input short protective circuit for PWM type audio frequency power amplifier according to claim 4, it is characterized in that, described input pin voltage detecting circuit comprises filter circuit, the second reference voltage generating circuit, the second voltage comparator and the second sequential logical circuit; Wherein,
The first input end of described second voltage comparator is connected through the input pin of described filter circuit with described PWM type audio frequency power amplifier; second input of described second voltage comparator is connected with the output of described second reference voltage generating circuit, and the Enable Pin that the output of described second voltage comparator produces circuit with Enable Pin and the described input short guard signal of the described PWM of output duty ratio difference detecting circuit respectively through described second sequential logical circuit is connected.
6. the input short protective circuit for PWM type audio frequency power amplifier according to claim 5, is characterized in that, described filter circuit comprises the first resistance and the first electric capacity; Wherein,
The first end of described first resistance is connected with the input pin of described PWM type audio frequency power amplifier, and the second end of described first resistance is connected with the first input end of described second voltage comparator; The first end of described first electric capacity is connected with the first input end of described second voltage comparator, the second end ground connection of described first electric capacity.
7. the input short protective circuit for PWM type audio frequency power amplifier according to claim 6, it is characterized in that, described input short guard signal produces circuit and comprises operating voltage input, the 3rd reference voltage generating circuit, the first reference current source, the second reference current source, tertiary voltage comparator, duration testing circuit, PMOS, NMOS tube and charge-discharge circuit; Wherein,
The grid of described PMOS is connected with the described output exporting PWM duty ratio difference detecting circuit, and the source electrode of described PMOS is connected with the negative pole of described first reference current source, and the positive pole of described first reference current source is connected with described operating voltage input; The drain electrode of described PMOS is connected with described charge-discharge circuit; The drain electrode of described NMOS tube is connected with described charge-discharge circuit, the output that grid and the described maximum duty cycle difference of described NMOS tube produce circuit is connected, the source electrode of described NMOS tube is connected with the positive pole of described second reference current source, the minus earth of described second reference current source; The first input end of described tertiary voltage comparator is connected with the drain electrode of described NMOS tube, second input of described tertiary voltage comparator is connected with the output of described 3rd reference voltage generating circuit, the Enable Pin of described tertiary voltage comparator is connected with the output of described input pin voltage detecting circuit, and the output of described tertiary voltage comparator is connected through the control end of described duration testing circuit with described pwm signal output circuit.
8. the input short protective circuit for PWM type audio frequency power amplifier according to claim 7, is characterized in that, described charge-discharge circuit comprises the second resistance and the second electric capacity; Wherein,
The first end of described second resistance is connected with the drain electrode of described PMOS, and the second end of described second resistance is connected with the first input end of described tertiary voltage comparator
;the first end of described second electric capacity is connected with the second end of described second resistance, the second end ground connection of described second electric capacity.
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| CN201520230367.2U CN204559091U (en) | 2015-04-16 | 2015-04-16 | For the input short protective circuit of PWM type audio frequency power amplifier |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104836192A (en) * | 2015-04-16 | 2015-08-12 | 何邦君 | Input short-circuit protecting circuit for PWM (Pulse-Width Modulation) type audio power amplifier |
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2015
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104836192A (en) * | 2015-04-16 | 2015-08-12 | 何邦君 | Input short-circuit protecting circuit for PWM (Pulse-Width Modulation) type audio power amplifier |
| CN104836192B (en) * | 2015-04-16 | 2018-02-09 | 深圳市一生微电子有限公司 | Input short protection circuit for PWM type audio frequency power amplifier |
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Effective date of registration: 20160503 Address after: 518000 Guangdong city of Shenzhen province Baoan District Xixiang Street Silver Road No. 4 HuaFeng Baoan Chi Technology Park H block four, building 422, No. 433 Patentee after: Shenzhen life Microelectronics Co., Ltd. Address before: Kwai Chung Street Yadi village in Longgang District of Shenzhen City, Guangdong province 518102 Patentee before: He Bangjun |
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