CN202663614U - Low-power light emitting diode (LED) constant-current power supply - Google Patents
Low-power light emitting diode (LED) constant-current power supply Download PDFInfo
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- CN202663614U CN202663614U CN 201220303469 CN201220303469U CN202663614U CN 202663614 U CN202663614 U CN 202663614U CN 201220303469 CN201220303469 CN 201220303469 CN 201220303469 U CN201220303469 U CN 201220303469U CN 202663614 U CN202663614 U CN 202663614U
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Abstract
The utility model discloses a low-power light emitting diode (LED) constant-current power supply, which comprises a primary side circuit, a secondary side circuit and a control circuit, wherein the primary side circuit is coupled with the secondary side circuit through a transformer; the primary side circuit comprises an input rectification filter circuit and a switch energy conversion circuit; the switch energy conversion circuit comprises a metal oxide semiconductor (MOS) tube and a primary winding of the transformer; the control circuit comprises a pulse width modulation (PWM) control chip, a current sampling resistor and a chip power supply circuit; the gate of the MOS tube is connected with the gate driving pin of the PWM control chip through a driving resistor; the drain of the MOS tube is connected with the first end of the primary winding of the transformer; the second end of the primary winding of the transformer is connected with a positive electrode of the output end of the input rectification filter circuit; the source of the MOS tube is grounded through the current sampling resistor; and the current detection pin of the PWM control chip is connected with the source of the MOS tube. The low-power LED constant-current power supply can stabilize output current without depending on feedback of a secondary side and is simple in circuit and relatively low in cost; and the reliability of the circuit is improved.
Description
[technical field]
The utility model relates to Switching Power Supply, relates in particular to a kind of low-power LED constant-current supply.
[background technology]
The LED constant-current supply is a kind of of LED power supply, is to adopt switching power converters, makes the constant-current supply of isolated form, its constant output current and adjustable.Low-power LED constant-current supply power in 30W, mainly as the LED fluorescent lamp, the low-power LED lamp driving power source such as bulb lamp or as charger.
Traditional isolation drive power acquisition comes constant output current with time limit feedback technique, plays preferably constant current effect.Inferior limit feedback constant current Technology Need increases time limit feedback circuit, needs to increase comparison circuit, voltage stabilizing circuit, light-coupled isolation, precision resistance sampling etc.So the components and parts that inferior limit feedback has increased cost, increase have reduced the reliability of circuit to a certain extent.
[summary of the invention]
The technical problems to be solved in the utility model provides that a kind of circuit is simple, and cost is lower, and reliability is the low-power LED constant-current supply preferably.
In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is, a kind of low-power LED constant-current supply comprises former limit circuit, secondary circuit and control circuit, and described former limit circuit and secondary circuit are by transformer coupled; Described former limit circuit comprises input rectifying filter circuit and switch power conversion circuits, described switch power conversion circuits comprises the former limit winding of metal-oxide-semiconductor and described transformer, described control circuit comprises pwm chip, current sampling resistor and chip power supply circuit, the grid of metal-oxide-semiconductor connects pwm chip by driving resistance grid drives pin, the drain electrode of metal-oxide-semiconductor connects the first end of transformer primary side winding, the positive pole of the second termination input rectifying filter circuit output of transformer primary side winding; The source electrode of metal-oxide-semiconductor is by current sampling resistor ground connection, and the current detecting pin of pwm chip connects the source electrode of metal-oxide-semiconductor.
Above-described low-power LED constant-current supply, described control circuit comprise resistance to earth and diode over the ground, an end ground connection of resistance to earth, and another termination is the anode of diode over the ground, and the negative electrode of the diode grid that connects pwm chip drives pin over the ground.
Above-described low-power LED constant-current supply, described chip power supply circuit comprises startup power supply circuits and work power supply circuits, described startup power supply circuits comprise starting resistance, and the power supply pin of pwm chip connects the positive pole of rectification filter circuit output end by starting resistance; Described transformer comprises auxiliary winding, and the work power supply circuits comprise rectifier diode and filter circuit; The anode of one termination rectifier diode of auxiliary winding, other end ground connection; The negative electrode of rectifier diode connects the input of filter circuit, and the anode of the output of filter circuit connects the power supply pin of pwm chip, the minus earth of the output of filter circuit.
Above-described low-power LED constant-current supply, described control circuit comprises compensating circuit, described compensating circuit comprises compensating resistance, the first building-out capacitor and the second building-out capacitor; Compensating resistance is with after the first building-out capacitor is connected in series, the compensation pin of a termination pwm chip, other end ground connection; The compensation pin of the second building-out capacitor one termination pwm chip, other end ground connection.
Above-described low-power LED constant-current supply, described control circuit comprises overvoltage crowbar, and described overvoltage crowbar comprises the first sampling resistor and the second sampling resistor, after the first sampling resistor and the second sampling resistor serial connection, the positive pole of one termination rectifier diode, other end ground connection; The overvoltage protection pin of pwm chip connects the tie point between the first sampling resistor and the second sampling resistor.
Above-described low-power LED constant-current supply comprises the RCD buffer circuit, and the RCD buffer circuit comprises buffering diode, buffer capacitor, the first buffer resistance and the second buffer resistance; The anode of buffering diode connects the first end of transformer primary side winding by the first buffer resistance, and the negative electrode of buffering diode connects the second end of transformer primary side winding by buffer capacitor; The second buffer resistance and buffer capacitor also connect.
Above-described low-power LED constant-current supply, described pwm chip are the SY5800 control chips.
The utility model low-power LED constant-current supply does not need to feed back constant output current by inferior limit, need to not increase on inferior limit comparison circuit, voltage stabilizing circuit, light-coupled isolation, precision resistance sampling, not only circuit is simple, and cost is lower, and has improved the reliability of circuit.
[description of drawings]
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
Fig. 1 is the circuit diagram of the utility model low-power LED constant-current supply embodiment.
Fig. 2 is the pinouts of the utility model low-power LED constant-current supply embodiment pwm chip SY5800.
[embodiment]
In the embodiment of the utility model low-power LED constant-current supply shown in Figure 1, the low-power LED constant-current supply comprises former limit circuit, secondary circuit, RCD buffer circuit and control circuit, and former limit circuit and secondary circuit are by transformer T1 coupling.Former limit circuit comprises input rectifying filter circuit and switch power conversion circuits,
The switch power conversion circuits comprises the former limit winding of metal-oxide-semiconductor Q1 and transformer T1.
Control circuit comprises pwm chip SY5800, chip power supply circuit, compensating circuit and overvoltage crowbar.
The grid of metal-oxide-semiconductor Q1 meets pwm chip SY5800 by driving resistance R 17 grid drives pin DRV, and the drain electrode of metal-oxide-semiconductor Q1 connects the first end of the former limit of transformer T1 winding, the positive pole of the second termination input rectifying filter circuit output of the former limit of transformer T1 winding.The current detecting pin ISEN of pwm chip SY5800 connects the source electrode of metal-oxide-semiconductor Q1, the source electrode of metal-oxide-semiconductor Q1 passes through current sampling resistor ground connection, and current sampling resistor is composed in parallel by resistance R 18, R19, R23 and R24.
For the unsettled rear misoperation of the grid level that prevents metal-oxide-semiconductor Q1, the end ground connection of resistance to earth R3, another termination is the anode of diode D4 over the ground, the negative electrode of diode D4 meets the grid driving pin DRV of pwm chip SY5800 over the ground, when SY5800 quits work, allow the electric charge of electric capacity bleeds off by this resistance R 3 between the grid source electrode.
Chip power supply circuit comprises startup power supply circuits and work power supply circuits.
Start power supply circuits and comprise starting resistance, the power supply pin VIN of pwm chip SY5800 connects the positive pole of rectification filter circuit output end by starting resistance; Starting resistance is made of resistance R 9, R10 and R11 series connection.
The work power supply circuits are comprised of auxiliary winding, rectifier diode D3 and the filter circuit of transformer T1.The anode of one termination rectifier diode D3 of auxiliary winding, other end ground connection.The negative electrode of rectifier diode D3 connects the input of filter circuit, and the anode of the output of filter circuit connects the power supply pin VIN of pwm chip SY5800, the minus earth of the output of filter circuit.Filter circuit is comprised of resistance R 16, capacitor C 3, C8 and C6.
Compensating circuit comprises compensating resistance R8, building-out capacitor C2 and building-out capacitor C4.After compensating resistance R8, the building-out capacitor C2 serial connection, the compensation pin COMP of a termination pwm chip SY5800, other end ground connection.The compensation pin COMP of building-out capacitor C4 one termination pwm chip SY5800, other end ground connection.Compensating circuit is conducive to improve the defective that flicker occurs the LED lamp.
Overvoltage crowbar comprises sampling resistor R6 and sampling resistor R7, after sampling resistor R6 and the sampling resistor R7 serial connection, and the positive pole of resistance R 6 one termination rectifier diode D3, other end ground connection.The overvoltage protection pin ZCS of pwm chip SY5800 connects the tie point between sampling resistor R6 and the sampling resistor R7.
The RCD buffer circuit comprises buffering diode D2, buffer capacitor C7, buffer resistance R13, R14 and R15.The anode of buffering diode D2 connects the first end of the former limit of transformer T1 winding by buffer resistance R15, and the negative electrode of buffering diode D2 connects the second end of the former limit of transformer T1 winding by buffer capacitor C7.Buffer resistance R13, R14 and buffer capacitor C7 also connect.
The above embodiment of the utility model low-power LED constant-current supply does not need to feed back constant output current by inferior limit, and inferior limit no longer needs comparison circuit, voltage stabilizing circuit, light-coupled isolation, precision resistance sampling; The utility model not only circuit is simple, and cost is lower, and has improved the reliability of circuit.
Claims (7)
1. a low-power LED constant-current supply comprises former limit circuit, secondary circuit and control circuit, and described former limit circuit and secondary circuit are by transformer coupled; Described former limit circuit comprises input rectifying filter circuit and switch power conversion circuits, described switch power conversion circuits comprises the former limit winding of metal-oxide-semiconductor and described transformer, it is characterized in that, described control circuit comprises pwm chip, current sampling resistor and chip power supply circuit, the grid of metal-oxide-semiconductor connects pwm chip by driving resistance grid drives pin, the drain electrode of metal-oxide-semiconductor connects the first end of transformer primary side winding, the positive pole of the second termination input rectifying filter circuit output of transformer primary side winding; The source electrode of metal-oxide-semiconductor is by current sampling resistor ground connection, and the current detecting pin of pwm chip connects the source electrode of metal-oxide-semiconductor.
2. low-power LED constant-current supply according to claim 1, it is characterized in that described control circuit comprises resistance to earth and diode over the ground, an end ground connection of resistance to earth, another termination is the anode of diode over the ground, and the negative electrode of diode connects the grid driving pin of pwm chip over the ground.
3. low-power LED constant-current supply according to claim 1, it is characterized in that, described chip power supply circuit comprises startup power supply circuits and work power supply circuits, described startup power supply circuits comprise starting resistance, and the power supply pin of pwm chip connects the positive pole of rectification filter circuit output end by starting resistance; Described transformer comprises auxiliary winding, and the work power supply circuits comprise rectifier diode and filter circuit; The anode of one termination rectifier diode of auxiliary winding, other end ground connection; The negative electrode of rectifier diode connects the input of filter circuit, and the anode of the output of filter circuit connects the power supply pin of pwm chip, the minus earth of the output of filter circuit.
4. low-power LED constant-current supply according to claim 1 is characterized in that, described control circuit comprises compensating circuit, and described compensating circuit comprises compensating resistance, the first building-out capacitor and the second building-out capacitor; Compensating resistance is with after the first building-out capacitor is connected in series, the compensation pin of a termination pwm chip, other end ground connection; The compensation pin of the second building-out capacitor one termination pwm chip, other end ground connection.
5. low-power LED constant-current supply according to claim 3, it is characterized in that, described control circuit comprises overvoltage crowbar, described overvoltage crowbar comprises the first sampling resistor and the second sampling resistor, after the first sampling resistor and the second sampling resistor serial connection, the positive pole of one termination rectifier diode, other end ground connection; The overvoltage protection pin of pwm chip connects the tie point between the first sampling resistor and the second sampling resistor.
6. low-power LED constant-current supply according to claim 1 is characterized in that, comprises the RCD buffer circuit, and the RCD buffer circuit comprises buffering diode, buffer capacitor, the first buffer resistance and the second buffer resistance; The anode of buffering diode connects the first end of transformer primary side winding by the first buffer resistance, and the negative electrode of buffering diode connects the second end of transformer primary side winding by buffer capacitor; The second buffer resistance and buffer capacitor also connect.
7. the described low-power LED constant-current supply of arbitrary claim in 6 according to claim 1 is characterized in that described pwm chip is the SY5800 chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220303469 CN202663614U (en) | 2012-06-27 | 2012-06-27 | Low-power light emitting diode (LED) constant-current power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220303469 CN202663614U (en) | 2012-06-27 | 2012-06-27 | Low-power light emitting diode (LED) constant-current power supply |
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| Publication Number | Publication Date |
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| CN202663614U true CN202663614U (en) | 2013-01-09 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220303469 Expired - Fee Related CN202663614U (en) | 2012-06-27 | 2012-06-27 | Low-power light emitting diode (LED) constant-current power supply |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103337896A (en) * | 2013-07-16 | 2013-10-02 | 浙江湖州森富机电有限责任公司 | Intelligent charger |
| CN103338560A (en) * | 2013-07-03 | 2013-10-02 | 深圳市通普科技有限公司 | LED supply circuit |
| CN104378887A (en) * | 2014-11-21 | 2015-02-25 | 成都芯源系统有限公司 | Led drive circuit and control method thereof |
-
2012
- 2012-06-27 CN CN 201220303469 patent/CN202663614U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103338560A (en) * | 2013-07-03 | 2013-10-02 | 深圳市通普科技有限公司 | LED supply circuit |
| CN103337896A (en) * | 2013-07-16 | 2013-10-02 | 浙江湖州森富机电有限责任公司 | Intelligent charger |
| CN104378887A (en) * | 2014-11-21 | 2015-02-25 | 成都芯源系统有限公司 | Led drive circuit and control method thereof |
| CN104378887B (en) * | 2014-11-21 | 2016-11-30 | 成都芯源系统有限公司 | Led drive circuit and control method thereof |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 518000, Guangdong, Shenzhen, Baoan District Fuyong Han Industrial Park 4 Patentee after: Shenzhen Yaham Optoelectronics Co., Ltd. Patentee after: Beijing Yun Xingyu transport science and techonologies incorporated company Address before: 518000, Guangdong, Shenzhen, Baoan District Fuyong Han Industrial Park 4 Patentee before: Shenzhen Yaham Optoelectronics Co., Ltd. Patentee before: Beijing Yunxingyu Traffic Engineering Co., Ltd. |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130109 Termination date: 20160627 |