CN202748690U - Power limiting circuit based on LM2576 series - Google Patents
Power limiting circuit based on LM2576 series Download PDFInfo
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- CN202748690U CN202748690U CN 201220294142 CN201220294142U CN202748690U CN 202748690 U CN202748690 U CN 202748690U CN 201220294142 CN201220294142 CN 201220294142 CN 201220294142 U CN201220294142 U CN 201220294142U CN 202748690 U CN202748690 U CN 202748690U
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- triode
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- signal input
- limiting circuit
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Abstract
The utility model relates to a power limiting circuit based on LM2576 series. The power limiting circuit is characterized by comprising a LM2576 series chip, wherein the signal input end of the LM2576 series chip is connected with a base of a triode Q1 by a resistor R2, an emitter of the triode Q1 is connected with a 24V power supply, a resistor R1 is connected between the emitter of the triode Q1 and the signal input end of the LM2576 series chip, a capacitor C1 is connected between the emitter and the base of the triode Q1, the signal input end of the LM2576 series chip is grounded through the capacitor, and a collector of the triode Q1 is connected with a FB (feedback) pin of the LM2576 series chip. Compared with the prior art, the power limiting circuit has the advantage that when a load has short circuiting, the input end of the load stills works, the triode Q1 is in a conduction state, voltage of the FB pin of the LM2576 series chip does not change to zero, and then the circuit is protected.
Description
Technical field
The utility model relates to a kind of power limit circuit based on LM2576 series.
Background technology
In a lot of application scenarios, not close-connected between power supply and the equipment, such as the comprehensive power case of our company to the safe city exploitation, specific requirement at that time is: the AC220V input, AC24V output and DC12V(3A) export, and a lot of IC(2576 appear after the initial stage delivery) and heating damage phenomenon, by observation, do not notice when being erecting equipment that DC12V polarity and actual energising far fall behind installation period again and cause the long-term short circuit of DC12V, thereby damage.
Summary of the invention
The purpose of this utility model is to overcome the shortcoming of prior art, and a kind of power limit circuit based on LM2576 series with defencive function is provided.
For solving above technical matters, the technical solution of the utility model is: based on the power limit circuit of LM2576 series, it is characterized in that: it comprises the LM2576 family chip, the signal input part of LM2576 family chip is connected to the base stage of triode Q1 by resistance R 2, the emitter of triode Q1 is connected to the 24V power supply, be connected with resistance R 1 between the signal input part of the emitter of triode Q1 and LM2576 family chip, be connected with capacitor C 1 between the emitter of triode Q1 and the base stage, ground connection after the signal input part series capacitance of LM2576 family chip, the collector of triode Q1 are connected to the FB pin of LM2576 family chip.
The contrast prior art; technical solutions of the utility model have the following advantages: when short circuit appearred in load, because input end is still working on, triode Q1 was in conducting state; the FB pin voltage of LM2576 family chip can not become zero yet, plays the pipeline protective effect.
Description of drawings
Fig. 1 is the circuit diagram of the utility model embodiment.
Embodiment
By reference to the accompanying drawings the utility model is described in further detail below by embodiment.
Please refer to Fig. 1, the utility model embodiment is based on the power limit circuit of LM2576 series, it comprises the LM2576 family chip, the signal input part of LM2576 family chip is connected to the base stage of triode Q1 by resistance R 2, the emitter of triode Q1 is connected to the 24V power supply, be connected with resistance R 1 between the signal input part of the emitter of triode Q1 and LM2576 family chip, be connected with capacitor C 1 between the emitter of triode Q1 and the base stage, the signal input part series connection of LM2576 family chip is by capacitor C 2, ground connection behind the shunt capacitance that capacitor C 3 consists of, the collector of triode Q1 is connected to the FB pin of LM2576 family chip.
Know-why: when resistance R 3 is used for normal operation as the adjustment of output voltage; Current sample when resistance R 1 is used for this circuit working, when the electric current that flows through from top to bottom when it surpasses certain numerical value, triode Q1 will conducting, 4 pin of IC1 (FB pin) voltage will obtain very large rising, inside principle according to IC, IC will descend output voltage, thereby has reduced the power stage of circuit.The effect of resistance R 2 and capacitor C 1 is the emitter to base voltage of level and smooth triode Q1.
Above content is in conjunction with concrete embodiment further detailed description of the utility model, can not assert that implementation of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field, without departing from the concept of the premise utility, can also make some simple deduction or replace, all should be considered as belonging to protection domain of the present utility model.
Claims (1)
1. based on the power limit circuit of LM2576 series, it is characterized in that: it comprises the LM2576 family chip, the signal input part of LM2576 family chip is connected to the base stage of triode Q1 by resistance R 2, the emitter of triode Q1 is connected to the 24V power supply, be connected with resistance R 1 between the signal input part of the emitter of triode Q1 and LM2576 family chip, be connected with capacitor C 1 between the emitter of triode Q1 and the base stage, ground connection after the signal input part series capacitance of LM2576 family chip, the collector of triode Q1 are connected to the FB pin of LM2576 family chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220294142 CN202748690U (en) | 2012-06-21 | 2012-06-21 | Power limiting circuit based on LM2576 series |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220294142 CN202748690U (en) | 2012-06-21 | 2012-06-21 | Power limiting circuit based on LM2576 series |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202748690U true CN202748690U (en) | 2013-02-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220294142 Expired - Fee Related CN202748690U (en) | 2012-06-21 | 2012-06-21 | Power limiting circuit based on LM2576 series |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202748690U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104102269A (en) * | 2014-07-20 | 2014-10-15 | 苏州塔可盛电子科技有限公司 | Novel power limiting circuit |
-
2012
- 2012-06-21 CN CN 201220294142 patent/CN202748690U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104102269A (en) * | 2014-07-20 | 2014-10-15 | 苏州塔可盛电子科技有限公司 | Novel power limiting circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| 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: 20130220 Termination date: 20180621 |