CN202906460U - A circuit used for preventing mis-protection of a PWM chip - Google Patents
A circuit used for preventing mis-protection of a PWM chip Download PDFInfo
- Publication number
- CN202906460U CN202906460U CN 201220590325 CN201220590325U CN202906460U CN 202906460 U CN202906460 U CN 202906460U CN 201220590325 CN201220590325 CN 201220590325 CN 201220590325 U CN201220590325 U CN 201220590325U CN 202906460 U CN202906460 U CN 202906460U
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- pwm chip
- voltage
- circuit
- protection
- resistance
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Abstract
The utility model discloses a circuit used for preventing mis-protection of a PWM chip. The circuit comprises a PWM chip and a voltage-regulator tube. The feedback end of the PWM chip is connected with the cathode of the voltage-regulator tube. The anode of the voltage-regulator tube is connected with ground. The beneficial effects of the circuit are that the PWM chip does not enter a protective mode because of instantaneous high voltage of a load, that the PWM chip performs overcurrent protection and short circuit protection by using the current detecting end of the PWM chip so as to increase load capability of a driving power supply. The circuit is suitable for electronic products with large varying load current such as power amplifier power supplies and printer power supplies or the like.
Description
Technical field
The utility model relates to the driving power technical field, relates in particular to a kind of circuit be used to preventing the protection of PWM chip mistake.
Background technology
In the existing electronic product, be circuit supply by driving power usually, these circuit are connected to driving power as load.For avoiding the excessive threat that causes of load current; usually realize overload protection by the PWM chip in the driving power; progressively increase along with load current; the feedback end voltage of PWM chip also can progressively raise; when the voltage of feedback end rises to the threshold voltage of PWM chip; the PWM chip will enter protected mode, thereby, driving power is in protects have the hiccups state or no-output.But; in the larger occasion of load current transient change; products such as amplifier power supply, printer power supply; the PWM chip can be owing to the false judgment to instantaneous high pressure enters protected mode; thereby electronic product is quit work, and this situation is that design and R﹠D work have caused very large technical barrier.Simultaneously, in the prior art, do not disclosed the method that can prevent the protection of PWM chip mistake, therefore, existing driving power is not suitable for load current variation electronic product greatly yet.
The utility model content
The technical problems to be solved in the utility model is, a kind of circuit be used to preventing the protection of PWM chip mistake is provided, and is applicable to load current variation electronic product greatly to make driving power.
For solving the problems of the technologies described above, the utility model adopts following technical scheme.
A kind of circuit be used to preventing the protection of PWM chip mistake, it includes a PWM chip and a voltage-stabiliser tube, and the feedback end of described PWM chip is connected to the negative electrode of voltage-stabiliser tube, the plus earth of described voltage-stabiliser tube.
Preferably, this circuit also includes an optocoupler and an a reference source, the photosensitive tube collector electrode of described optocoupler is connected to feedback end, its photosensitive tube grounded emitter, the luminous tube anode of this optocoupler is connected to power end by the first resistance, and its luminous tube negative electrode is connected to the negative electrode of a reference source, be connected with the second resistance between the anode of this optocoupler and the negative electrode, the plus earth of described a reference source, its control utmost point is connected to the output of driving power by the 4th resistance, and this control utmost point is also by the 5th grounding through resistance.
Preferably, the negative electrode of described a reference source also passes through the second electric capacity, the 3rd resistance and the 5th grounding through resistance of successively connection.
Preferably, described feedback end is by the first capacity earth.
The disclosed circuit for preventing the protection of PWM chip mistake of the utility model; be connected by voltage-stabiliser tube between the feedback end of PWM chip and the ground; when load current increases; the feedback end FB voltage of PWM chip raises; and make the output voltage of the output end vo ut of driving power reduce; wherein; the reduction of driving power output voltage and the increase of load current keep linear change; when the voltage of feedback end rises to the clamper value of voltage-stabiliser tube; voltage-stabiliser tube is because of the reverse breakdown conducting, at this moment, even load current continues to increase; the voltage of feedback end still remains on the clamper value of voltage-stabiliser tube and can not reach the threshold value of PWM chip, and the PWM chip can not enter protected mode.Simultaneously, because the current detecting end of PWM chip self has the effect of overcurrent protection and short-circuit protection, so, can realize overload protection to driving power by this current detecting end.The beneficial effects of the utility model are; the PWM chip can not enter protected mode because of the instantaneous high pressure of load; simultaneously; also the current detecting end by himself carries out overcurrent protection and short-circuit protection; improved the carrying load ability of driving power, be applicable to as in the larger electronic product of amplifier power supply, printer power supply even load curent change.
Description of drawings
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment
Below in conjunction with drawings and Examples the utility model is done more detailed description.
The utility model discloses a kind of circuit be used to preventing the protection of PWM chip mistake, and as shown in Figure 1, it includes a PWM chip U3 and a voltage-stabiliser tube ZD1, and the feedback end FB of described PWM chip U3 is connected to the negative electrode of voltage-stabiliser tube ZD1, the plus earth of described voltage-stabiliser tube ZD1.In the foregoing circuit structure; be connected by voltage-stabiliser tube ZD1 between the feedback end FB of PWM chip U3 and the ground; when load current increases; the feedback end FB voltage of PWM chip raises; and U3 modulates the pulse width signal of its output by the PWM chip; make the output voltage of the output end vo ut of driving power reduce; wherein; the reduction of driving power output voltage and the increase of load current keep linear change; when the voltage of feedback end FB rises to the clamper value of voltage-stabiliser tube ZD1; voltage-stabiliser tube ZD1 is because of the reverse breakdown conducting; at this moment; can not reach the threshold value of PWM chip U3 even load current continuation increase, the voltage of feedback end FB still remain on the clamper value of voltage-stabiliser tube ZD1, PWM chip U3 can not enter protected mode.Simultaneously, because the current detecting end of PWM chip U3 self has the effect of overcurrent protection and short-circuit protection, so, can realize overload protection to driving power by this current detecting end.The beneficial effects of the utility model are; PWM chip U3 can not enter protected mode because of the instantaneous high pressure of load; and the current detecting end by himself carries out overcurrent protection and short-circuit protection; improved the carrying load ability of driving power, be applicable to as in the larger electronic product of amplifier power supply, printer power supply even load curent change.
As shown in Figure 1; should be used for preventing that the circuit of PWM chip mistake protection from also including an optocoupler U2 and an a reference source U1; the photosensitive tube collector electrode of described optocoupler U2 is connected to feedback end FB; its photosensitive tube grounded emitter; the luminous tube anode of this optocoupler U2 is connected to power end VDD by the first resistance R 1; its luminous tube negative electrode is connected to the negative electrode of a reference source U1; be connected with the second resistance R 2 between the anode of this optocoupler U2 and the negative electrode; the plus earth of described a reference source U1; its control utmost point is connected to the output end vo ut of driving power by the 4th resistance R 4, this control utmost point is also by the 5th resistance R 5 ground connection.In this circuit, when the output end voltage Vout of driving power has than minor swing, because the dividing potential drop effect of the 4th resistance R 4 and the 5th resistance R 5, the voltage of a reference source U1 control end also changes thereupon, and the on-state rate of a reference source U1 changes, thereby changed the angle of flow of optocoupler U2, because the photosensitive tube collector electrode of optocoupler U2 connects feedback end FB, its grounded emitter, the voltage of feedback end FB is changed along with the angle of flow of optocoupler U2, making PWM chip U3 according to the change in voltage of feedback end FB the pulse width signal of its output be modulated, thereby further adjust the voltage of the output end vo ut of driving power, suppress the fluctuation of output voltage.
As shown in Figure 1, the negative electrode of a reference source U1 is the second capacitor C 2, the 3rd resistance R 3 and the 5th resistance R 5 ground connection by connecting successively also, thus the noise jamming of filtering a reference source U1 negative electrode.Feedback end FB is by the first capacitor C 1 ground connection, with the noise jamming of filtering feedback end FB.
In the present embodiment, it is the voltage-stabiliser tube of 3V-5V that voltage-stabiliser tube ZD1 selects the clamper value, still, this is a preferred embodiment of the present utility model, be not limited to the utility model, in other embodiment of the present utility model, can also select the voltage-stabiliser tube of other clamper value.For example; can select a voltage-stabiliser tube that the clamper value is larger; to realize the protection to optocoupler U2; its protection philosophy is: when abnormal conditions occurring, as control IC lost efficacy or PCB layout between during the photosensitive tube short circuit of copper platinum short circuit, especially high-tension circuit and optocoupler U2; voltage-stabiliser tube ZD1 can be with the high voltage grounding shunt; protection optocoupler U2 can not burnt out by high voltage, and protection safety device makes product safer.
The disclosed a kind of circuit for preventing the protection of PWM chip mistake of the utility model; be connected by voltage-stabiliser tube ZD1 between the feedback end FB of PWM chip U3 and the ground; make PWM chip U3 can not enter protected mode because of the instantaneous high pressure of load, and realize overcurrent protection and short-circuit protection by the current detecting end of himself.Simultaneously, when the output end voltage Vout of driving power had than minor swing, PWM chip U3 can further adjust according to the change in voltage of feedback end FB the voltage of the output end vo ut of driving power, suppresses the fluctuation of output voltage.Therefore; the utility model has not only been realized overload protection; also improved the carrying load ability of driving power; be applicable to as in the larger electronic product of amplifier power supply, printer power supply even load curent change; captured larger technological difficulties in the driving power technical field, made driving power have more wide market prospects.
The above is the utility model preferred embodiment, is not limited to the utility model, all modifications of making in technical scope of the present utility model, is equal to and replaces or improvement etc., all should be included in the scope that the utility model protects.
Claims (4)
1. one kind is used for preventing the by mistake circuit of protection of PWM chip; it is characterized in that; this circuit includes a PWM chip (U3) and a voltage-stabiliser tube (ZD1), and the feedback end (FB) of described PWM chip (U3) is connected to the negative electrode of voltage-stabiliser tube (ZD1), the plus earth of described voltage-stabiliser tube (ZD1).
2. as claimed in claim 1 be used to preventing the by mistake circuit of protection of PWM chip; it is characterized in that; this circuit also includes an optocoupler (U2) and an a reference source (U1); the photosensitive tube collector electrode of described optocoupler (U2) is connected to feedback end (FB); its photosensitive tube grounded emitter; the luminous tube anode of this optocoupler (U2) is connected to power end (VDD) by the first resistance (R1); its luminous tube negative electrode is connected to the negative electrode of a reference source (U1); be connected with the second resistance (R2) between the anode of this optocoupler (U2) and the negative electrode; the plus earth of described a reference source (U1); its control utmost point is connected to the output (Vout) of driving power by the 4th resistance (R4), this control utmost point is also by the 5th resistance (R5) ground connection.
3. the circuit be used to preventing the protection of PWM chip mistake as claimed in claim 2 is characterized in that, the negative electrode of described a reference source (U1) is the second electric capacity (C2), the 3rd resistance (R3) and the 5th resistance (R5) ground connection by connecting successively also.
4. the circuit be used to preventing the protection of PWM chip mistake as claimed in claim 1 is characterized in that, described feedback end (FB) is by the first electric capacity (C1) ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220590325 CN202906460U (en) | 2012-11-09 | 2012-11-09 | A circuit used for preventing mis-protection of a PWM chip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220590325 CN202906460U (en) | 2012-11-09 | 2012-11-09 | A circuit used for preventing mis-protection of a PWM chip |
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| Publication Number | Publication Date |
|---|---|
| CN202906460U true CN202906460U (en) | 2013-04-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220590325 Expired - Lifetime CN202906460U (en) | 2012-11-09 | 2012-11-09 | A circuit used for preventing mis-protection of a PWM chip |
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| Country | Link |
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| CN (1) | CN202906460U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102916420A (en) * | 2012-11-09 | 2013-02-06 | 深圳市安科讯实业有限公司 | Circuit for preventing PWM chip from error protection |
-
2012
- 2012-11-09 CN CN 201220590325 patent/CN202906460U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102916420A (en) * | 2012-11-09 | 2013-02-06 | 深圳市安科讯实业有限公司 | Circuit for preventing PWM chip from error protection |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20130424 |
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| CX01 | Expiry of patent term |