CN202474804U - Protective circuit for LNB power-supply short circuit - Google Patents
Protective circuit for LNB power-supply short circuit Download PDFInfo
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- CN202474804U CN202474804U CN2012200386450U CN201220038645U CN202474804U CN 202474804 U CN202474804 U CN 202474804U CN 2012200386450 U CN2012200386450 U CN 2012200386450U CN 201220038645 U CN201220038645 U CN 201220038645U CN 202474804 U CN202474804 U CN 202474804U
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Abstract
The utility model discloses a protective circuit for an LNB power-supply short circuit, comprising an MOS transistor, a first resistor, a triode, a first diode, a second diode and a third resistor. A source electrode of the MOS transistor is connected with an output terminal of power supply and a drain electrode is connected with a voltage input terminal of an LNB module. The first resistor is connected between a grid electrode and the source electrode of the MOS transistor. The grid electrode of the MOS transistor is connected with a collector electrode of the triode. An emitter electrode of the triode is earthed. A cathode of the second diode is connected with a base electrode of the triode and an anode is connected with a control signal input terminal by the third resistor. An anode of the first diode is connected with the anode of the second diode and a cathode is connected with the LNB module. The protective circuit for the LNB power-supply short circuit in the utility model detects whether the LNB module is the short circuit by the first diode, when the LNB is the short circuit, the first diode is switched on and the triode and the MOS transistor are switched off, so that long-term short circuit protection can be provided for the power-supply circuit.
Description
Technical field
The utility model relates to short-circuit protection circuit, relates in particular to a kind of LNB power supply short-circuit protection circuit.
Background technology
Satellite set top box is a kind of equipment that is used for receiving satellite broadcast, TV signal, at home and abroad has very widely to use.Satellite set top box need be given low noise block downconverter (Low Noise Block, LNB) power supply 13/18V.In satellite set top box test, batch process and the actual process of using; The short-circuit conditions that causes because of a variety of causes such as user's misoperation or the faults of LNB own appears through regular meeting; If not having short-circuit protection, LNB power supply circuits just to have burns danger, thereby cause the set-top box functionality disappearance.
The utility model content
The utility model embodiment technical problem to be solved is, a kind of LNB power supply short-circuit protection circuit is provided, and can realize long short-circuit protection.
In order to solve the problems of the technologies described above; The utility model embodiment has proposed a kind of LNB power supply short-circuit protection circuit; Be connected operating voltage to be provided with power output end, comprise: metal-oxide-semiconductor, first resistance, triode, first diode, second diode and the 3rd resistance to the LNB module; The source electrode of said metal-oxide-semiconductor is connected with power output end; The drain electrode of said metal-oxide-semiconductor is connected with the voltage input end of said LNB module; Said first resistance is connected between the grid and source electrode of said metal-oxide-semiconductor, and the grid of said metal-oxide-semiconductor is connected with the collector electrode of said triode; The grounded emitter of said triode; The negative pole of said second diode is connected with the base stage of said triode, and the positive pole of said second diode is connected with the signal input end that is used to export high-low level through said the 3rd resistance; The positive pole of said first diode is connected with the positive pole of said second diode, and the negative pole of said first diode is connected with the voltage input end of said LNB module.
Further, between the source electrode of metal-oxide-semiconductor and power output end, also be connected with magnetic bead, between the collector electrode of the grid of said metal-oxide-semiconductor and said triode, also be provided with second resistance.
Further, said LNB power supply short-circuit protection circuit also comprises voltage conversion circuit, and said voltage conversion circuit is connected between the voltage input end of drain electrode and said LNB module of said metal-oxide-semiconductor
The LNB of the utility model power supply short-circuit protection circuit is through the whether short circuit of the first diode detection LNB module, first diode current flow when LNB is short-circuited, and triode and metal-oxide-semiconductor shutoff, and then can long short-circuit protection be provided to power supply circuits.
Description of drawings
Fig. 1 is the circuit diagram of the LNB power supply short-circuit protection circuit of the utility model embodiment.
Embodiment
The LNB power supply short-circuit protection circuit of the utility model as shown in Figure 1 is connected with power output end to the LNB module operating voltage to be provided.LNB power supply short-circuit protection circuit comprises: metal-oxide-semiconductor Q2, first resistance R 1, triode Q1, the first diode D1, the second diode D2 and the 3rd resistance R 3.Wherein, The source S of metal-oxide-semiconductor Q2 is connected with power output end; The drain D of metal-oxide-semiconductor Q2 is connected with the voltage input end of LNB module, and first resistance R 1 is connected between the grid G and source S of metal-oxide-semiconductor Q2, and the grid G of metal-oxide-semiconductor Q2 is connected with the collector electrode C of triode Q1.The emitter E ground connection of triode Q1; The negative pole of the second diode D2 is connected with the base stage B of triode Q1, and the positive pole of the second diode D2 is connected with the signal input end ON/OFF that is used to export high-low level through the 3rd resistance R 3; The positive pole of the first diode D1 is connected with the positive pole of stating the second diode D2, and the negative pole of the first diode D1 is connected with the voltage input end of LNB module.
Between the source S of metal-oxide-semiconductor Q2 and power output end, also be connected with magnetic bead L1, also can adopt inductance during practical implementation.Between the collector electrode C of the grid G of metal-oxide-semiconductor Q2 and triode Q1, also be provided with second resistance R 2.
LNB power supply short-circuit protection circuit also comprises voltage conversion circuit 1, and voltage conversion circuit 1 is connected between the voltage input end of drain D and LNB module of metal-oxide-semiconductor Q2,
When circuit was in normal operating conditions, metal-oxide-semiconductor Q2 was in conducting state and is transported to voltage transformation module 1 with the 12V voltage with power output end output.Press modular converter 1 to be used for becoming 13V voltage or 18V voltage operating voltage to be provided the 12V voltage transitions to the LNB module.The negative pole of the first diode D1 is connected with the voltage input end of LNB module and is used to detect the whether short circuit of LNB module; When the LNB module was short-circuited, the first diode D1 is shorted to earth also, and the voltage of the positive terminal of the first diode D1 is about 0.7V; The second diode D2 has connected again between the base stage B of the first diode D1 and triode Q1; And the conduction voltage drop of the second diode D2 is 0.7V, and this just makes base stage B and the voltage between the emitter E of triode Q1 less than 0.7V, and triode Q1 can't work; Thereby make the grid voltage of metal-oxide-semiconductor Q2 and source voltage be 12V, i.e. V
GS=0V, not conducting of metal-oxide-semiconductor Q2 this moment, thus the output voltage of voltage transformation module 1 is zero.When LNB module operate as normal, the first diode D1 is in cut-off state, the second diode D2 and the equal conducting of triode Q1, and then also conducting of metal-oxide-semiconductor Q2, and LNB power supply this moment short-circuit protection circuit is a LNB module normal power supply.
Owing to be provided with the 3rd resistance R 3; When the LNB module was short-circuited, the cathode voltage of the first diode D1 can remain 0.7V all the time, and triode Q1 does not work all the time; And then metal-oxide-semiconductor Q2 also is in cut-off state all the time, so just reached the purpose of long-time protection short circuit.
Signal input end ON/OFF is connected with main control unit; The operating state that can be used for ACTIVE CONTROL LNB power supply short-circuit protection circuit; During signal input end ON/OFF output high level; LNB power supply short-circuit protection circuit is in normal operating conditions, and when signal input end ON/OFF output low level, LNB power supply short-circuit protection circuit is in holding state.
The LNB power supply short-circuit protection circuit of the utility model adopts less components and parts but can realize long short-circuit protection, and its hardware cost is lower, easy to maintenance.
The above is the embodiment of the utility model; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the utility model principle; Can also make some improvement and retouching, these improvement and retouching also are regarded as the protection range of the utility model.
Claims (3)
1. a LNB power supply short-circuit protection circuit is connected to the LNB module operating voltage to be provided with power output end, it is characterized in that, comprising: metal-oxide-semiconductor, first resistance, triode, first diode, second diode and the 3rd resistance; The source electrode of said metal-oxide-semiconductor is connected with power output end; The drain electrode of said metal-oxide-semiconductor is connected with the voltage input end of said LNB module; Said first resistance is connected between the grid and source electrode of said metal-oxide-semiconductor, and the grid of said metal-oxide-semiconductor is connected with the collector electrode of said triode; The grounded emitter of said triode; The negative pole of said second diode is connected with the base stage of said triode, and the positive pole of said second diode is connected with the signal input end that is used to export high-low level through said the 3rd resistance; The positive pole of said first diode is connected with the positive pole of said second diode, and the negative pole of said first diode is connected with the voltage input end of said LNB module.
2. LNB as claimed in claim 1 power supply short-circuit protection circuit is characterized in that, between the source electrode of metal-oxide-semiconductor and power output end, also is connected with magnetic bead, between the collector electrode of the grid of said metal-oxide-semiconductor and said triode, also is provided with second resistance.
3. LNB as claimed in claim 1 power supply short-circuit protection circuit is characterized in that, said LNB power supply short-circuit protection circuit also comprises voltage conversion circuit, and said voltage conversion circuit is connected between the voltage input end of drain electrode and said LNB module of said metal-oxide-semiconductor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200386450U CN202474804U (en) | 2012-02-07 | 2012-02-07 | Protective circuit for LNB power-supply short circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200386450U CN202474804U (en) | 2012-02-07 | 2012-02-07 | Protective circuit for LNB power-supply short circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202474804U true CN202474804U (en) | 2012-10-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012200386450U Expired - Fee Related CN202474804U (en) | 2012-02-07 | 2012-02-07 | Protective circuit for LNB power-supply short circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN202474804U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108599123A (en) * | 2018-01-18 | 2018-09-28 | 深圳创维－Rgb电子有限公司 | The short-circuit protection circuit and television set of power switch |
| CN111934275A (en) * | 2019-05-13 | 2020-11-13 | 澜至电子科技（成都）有限公司 | Overcurrent protection circuit, control circuit, chip and control method |
| TWI818657B (en) * | 2022-08-03 | 2023-10-11 | 華碩電腦股份有限公司 | Power circuit and electronic device having the same |
-
2012
- 2012-02-07 CN CN2012200386450U patent/CN202474804U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108599123A (en) * | 2018-01-18 | 2018-09-28 | 深圳创维－Rgb电子有限公司 | The short-circuit protection circuit and television set of power switch |
| CN111934275A (en) * | 2019-05-13 | 2020-11-13 | 澜至电子科技（成都）有限公司 | Overcurrent protection circuit, control circuit, chip and control method |
| CN111934275B (en) * | 2019-05-13 | 2022-11-11 | 澜至电子科技（成都）有限公司 | Overcurrent protection circuit, control circuit, chip and control method |
| TWI818657B (en) * | 2022-08-03 | 2023-10-11 | 華碩電腦股份有限公司 | Power circuit and electronic device having the same |
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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: 20121003 Termination date: 20170207 |