CN203481803U - PWM output short circuit protection circuit - Google Patents
PWM output short circuit protection circuit Download PDFInfo
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- CN203481803U CN203481803U CN201320537449.2U CN201320537449U CN203481803U CN 203481803 U CN203481803 U CN 203481803U CN 201320537449 U CN201320537449 U CN 201320537449U CN 203481803 U CN203481803 U CN 203481803U
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Abstract
The utility model relates to a PWM output short circuit protection circuit. The problem that the prior PWM dimming circuit does not have a short circuit protection function is solved. The circuit comprises an input port, an output port, a MCU chip and a switching tube, wherein the input port is connected with the output port after being connected with a lead inductor, the MCU chip has a PWM output pin which is connected with a control end of the switching tube, one end of the switching tube is connected with the output port and the other end is grounded, a voltage dividing circuit is connected between the output port and the ground, and the MCU chip further has an external interrupt pin which is connected to the voltage dividing circuit. The PWM output short circuit protection circuit has the advantages that the short circuit protection function is added, the current after short circuit cannot rise to the maximum due to the lead inductor, output voltage drop is detected by using an external terminal of the MCU chip, and the switching tube is closed before the arrival of short-circuit large surge current to avoid the impact of large current on the switching tube so that the switching tube is protected.
Description
Technical field
The utility model relates to a kind of short-circuit protection technology, especially relates to a kind of PWM output short circuit protection circuit.
Background technology
Along with the development of LED technology, LED illumination is more applied.Increasing LED product introduction illumination market.And along with the raising of people to lighting requirement, there is increasing intelligent lighting product, as light modulation, toning product, the PWM light regulating technology all using in this series products, this circuit is used DC to DC structure mostly, uses single-chip microcomputer to produce pwm signal and carries out light modulation.Existing most of PWM light modulation circuit no-output short-circuit protection function, makes when there is output short-circuit because the output impedance of powerful DC power supply is very little, and the surge current of generation, up to 100 amperes, often damages switching tube.
Summary of the invention
The utility model is mainly the problem that in solution prior art, PWM light adjusting circuit does not have short-circuit protection function, provides a kind of circuit structure simple, effectively the PWM output short circuit protection circuit of protective circuit element.
Above-mentioned technical problem of the present utility model is mainly solved by following technical proposals: a kind of PWM output short circuit protection circuit, comprise input port, output port, MCU chip and switching tube, input port is connected with output port after by connecting lead wire inductance, MUC chip has PWM output pin, this PWM output pin connecting valve pipe control end, one end of switching tube connects output port, other end ground connection, between described output port and ground, be connected with dividing potential drop circuit, described MCU chip also has external interrupt pin, external interrupt pin is connected on dividing potential drop circuit.The utility model has increased short-circuit protection function on conventional PWM light modulation circuit; when output short-circuit and PWM are working, 0V is down to rapidly and is approached to output voltage; utilize the existence of lead-in inductance to make the electric current after short circuit can not rise to immediately maximum; rise time is conventionally at 10-40uS; and the interrupt response of MCU chip is conventionally in 1-3uS; by the external interrupt of MCU chip, detecting output voltage falls; thereby close PWM output; avoid the impact of large electric current to switching tube, protected switching tube.
As a kind of preferred version, described dividing potential drop circuit comprises resistance R 4 and resistance R 5, and resistance R 4 and R5 are connected between output port and ground, and external interrupt pin is connected on the tie point between resistance R 4 and resistance R 5 after by contact resistance R3.The resistance proportioning of adjusting resistance R4 and resistance R 5, when the dividing potential drop by dividing potential drop circuit makes to work, the external interrupt pin voltage of MCU chip is 5V.
As a kind of preferred version, in lead-in inductance, be parallel with diode D1, the anodal output port that connects of diode D1, diode D1 negative pole connects input port.This diode D1 plays the effect of protection switch pipe.In switching tube conduction period lead-in inductance, can produce certain voltage in theory, and close this voltage of the having no progeny output that can be added to when switching tube together with input voltage.In order to prevent that two voltage sums are higher than the withstand voltage access D1 of switching tube, its effect be exactly when switching tube turn-offs by the voltage clamping in lead-in inductance at 0.7V, with protection switch pipe.
As a kind of preferred version, described switching tube is metal-oxide-semiconductor Q, and PWM output is connected with metal-oxide-semiconductor Q grid after by contact resistance R1, and is connected with resistance R 2 between metal-oxide-semiconductor Q grid and ground, and metal-oxide-semiconductor Q drain electrode is connected with output pin, metal-oxide-semiconductor Q source ground.
As a kind of preferred version, ground connection after described external interrupt pin Opposite direction connection voltage stabilizing didoe Z.Voltage-stabiliser tube plays a protective role to MCU chip, prevents that overvoltage from causing damage to MCU chip.
As a kind of preferred version, described MCU chip has power supply input pin, input port forward connects diode D2, and after contact resistance R6, be connected on a three terminal regulator input, three terminal regulator output is connected with power supply input pin, between three terminal regulator input and ground, be parallel with capacitor C 1 and capacitor C 2, between three terminal regulator output and ground, be parallel with capacitor C 3, capacitor C 4 and capacitor C 5.This three terminal regulator is AS78L05, by three terminal regulator, the voltage stabilization of input port exported at 5V, and be MCU chip power supply.
Therefore; the utility model has the advantages that: increased short-circuit protection function; utilize the existence of lead-in inductance to make the electric current after short circuit can not rise to immediately maximum; with the exterior terminal of MUC chip, detecting output voltage falls; closing switch pipe before the large surge current of short circuit arrives; avoid the impact of large electric current to switching tube, protected switching tube.
Accompanying drawing explanation
Accompanying drawing 1 is a kind of electrical block diagram of the present utility model.
Embodiment
Below by embodiment, and by reference to the accompanying drawings, the technical solution of the utility model is described in further detail.
Embodiment:
A kind of PWM output short circuit protection circuit of the present embodiment, as shown in Figure 1, includes input port, output port, MCU chip, lead-in inductance, switching tube.Lead-in inductance is connected between input port and output port, MCU chip adopts PIC16F1822, this MCU chip has 8 each pins, comprising having power supply output pin, PWM output pin, external interrupt pin, between output port and ground, be connected in series with resistance R 4 and resistance R 5, this resistance R 4 and resistance R 5 form dividing potential drop circuit.External interrupt pin is connected on the tie point of resistance R 4 and resistance R 5 after by contact resistance R3, and external interrupt pin is also by Opposite direction connection voltage-stabiliser tube Z ground connection.Switching tube adopts metal-oxide-semiconductor Q, and the grid of metal-oxide-semiconductor Q is connected on PWM output pin after by contact resistance R1, and the grid of metal-oxide-semiconductor Q is also by ground connection after contact resistance R2.The drain electrode of metal-oxide-semiconductor Q connects output port, the source ground of metal-oxide-semiconductor Q.In lead-in inductance, be parallel with diode D1, the anodal output port that connects of diode D1, diode D1 negative pole connects input port.Between the power supply input pin of MCU chip and input port, be connected with three terminal regulator, this three terminal regulator adopts AS78L05, and it comprises input, output and ground end, ground end ground connection.Output port forward connects diode D2, then after series resistance R6, is connected on three terminal regulator input, and three terminal regulator output is connected on the power supply input pin of MCU chip.Between three terminal regulator input and ground, be parallel with in addition capacitor C 1 and capacitor C 2, between three terminal regulator output and ground, be parallel with capacitor C 3, capacitor C 4 and capacitor C 5.
Specific embodiment described herein is only to the explanation for example of the utility model spirit.The utility model person of ordinary skill in the field can make various modifications or supplements or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present utility model or surmount the defined scope of appended claims.
Although more used the terms such as input port, output port, lead-in inductance, MCU chip herein, do not got rid of the possibility of using other term.Use these terms to be only used to describe more easily and explain essence of the present utility model; They are construed to any additional restriction is all contrary with the utility model spirit.
Claims (6)
1. a PWM output short circuit protection circuit; comprise input port, output port, MCU chip and switching tube; input port is connected with output port after by connecting lead wire inductance; MUC chip has PWM output pin, this PWM output pin connecting valve pipe control end, and one end of switching tube connects output port; other end ground connection; it is characterized in that: between described output port and ground, be connected with dividing potential drop circuit, described MCU chip also has external interrupt pin, and external interrupt pin is connected on dividing potential drop circuit.
2. PWM output short circuit protection circuit according to claim 1; it is characterized in that described dividing potential drop circuit comprises resistance R 4 and resistance R 5; resistance R 4 and R5 are connected between output port and ground, and external interrupt pin is connected on the tie point between resistance R 4 and resistance R 5 after by contact resistance R3.
3. PWM output short circuit protection circuit according to claim 1 and 2, is characterized in that being parallel with diode D1 in lead-in inductance, the anodal output port that connects of diode D1, and diode D1 negative pole connects input port.
4. PWM output short circuit protection circuit according to claim 3; it is characterized in that described switching tube is metal-oxide-semiconductor Q; PWM output is connected with metal-oxide-semiconductor Q grid after by contact resistance R1; and between metal-oxide-semiconductor Q grid and ground, be connected with resistance R 2; metal-oxide-semiconductor Q drain electrode is connected with output pin, metal-oxide-semiconductor Q source ground.
5. PWM output short circuit protection circuit according to claim 2, is characterized in that ground connection after described external interrupt pin Opposite direction connection voltage stabilizing didoe Z.
6. PWM output short circuit protection circuit according to claim 1 and 2; it is characterized in that described MCU chip has power supply input pin; input port forward connects diode D2; and after contact resistance R6, be connected on a three terminal regulator input; three terminal regulator output is connected with power supply input pin; between three terminal regulator input and ground, be parallel with capacitor C 1 and capacitor C 2, between three terminal regulator output and ground, be parallel with capacitor C 3, capacitor C 4 and capacitor C 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320537449.2U CN203481803U (en) | 2013-08-30 | 2013-08-30 | PWM output short circuit protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320537449.2U CN203481803U (en) | 2013-08-30 | 2013-08-30 | PWM output short circuit protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203481803U true CN203481803U (en) | 2014-03-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320537449.2U Expired - Fee Related CN203481803U (en) | 2013-08-30 | 2013-08-30 | PWM output short circuit protection circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN203481803U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103490391A (en) * | 2013-08-30 | 2014-01-01 | 宁波凯耀电器制造有限公司 | PWM output short-circuit protection circuit |
| CN105974992A (en) * | 2016-06-03 | 2016-09-28 | 沙洲职业工学院 | Method and device for PWM control signal transmission in intense electromagnetic interference environment |
-
2013
- 2013-08-30 CN CN201320537449.2U patent/CN203481803U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103490391A (en) * | 2013-08-30 | 2014-01-01 | 宁波凯耀电器制造有限公司 | PWM output short-circuit protection circuit |
| CN103490391B (en) * | 2013-08-30 | 2016-08-10 | 宁波凯耀电器制造有限公司 | A kind of PWM output short-circuit protection circuit |
| CN105974992A (en) * | 2016-06-03 | 2016-09-28 | 沙洲职业工学院 | Method and device for PWM control signal transmission in intense electromagnetic interference environment |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140312 Termination date: 20190830 |
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| CF01 | Termination of patent right due to non-payment of annual fee |