CN201533345U - LNB switching circuit of satellite set-top box - Google Patents
LNB switching circuit of satellite set-top box Download PDFInfo
- Publication number
- CN201533345U CN201533345U CN2009202058389U CN200920205838U CN201533345U CN 201533345 U CN201533345 U CN 201533345U CN 2009202058389 U CN2009202058389 U CN 2009202058389U CN 200920205838 U CN200920205838 U CN 200920205838U CN 201533345 U CN201533345 U CN 201533345U
- Authority
- CN
- China
- Prior art keywords
- lnb
- switching circuit
- circuit
- voltage
- npn triode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
The utility model relates to an LNB switching circuit of a satellite set-top box, which comprises an LNB switching circuit control chip, a voltage conversion circuit, a control switching circuit and an LNB voltage switch control circuit, as well as an MOS tube Q4, wherein a gate G and a source S of the MOS tube Q4 are connected with the voltage conversion circuit and the LNB voltage switch control circuit, and a drain D of the MOS tube Q4 is connected with the control switching circuit and outputs voltage LNA-IN. The constructed LNB switching circuit of the satellite set-top box adopts the short circuit protection measurement measures. When a metal wire core of an antenna and a housing of the set-top box are in short circuit, the overcurrent protection function of a power panel is started normally, so that the whole LNB switching circuit can play the short circuit protection role. The LNB switching circuit of the satellite set-top box has the advantages of small calorific value, low cost, and small occupied space of elements on a PCB.
Description
Technical field
The utility model relates to a kind of switching circuit, relates in particular to a kind of satellite set top box LNB switching circuit that contains short-circuit protection.
Background technology
Flourish along with digital satellite receiver, LNB (Low Noise Block, low noise block are called for short " LNB ") switching circuit is widely used in satellite set top box.The LNB switching circuit mainly comprises following several control signal: voltage conversion circuit: switch in the 13/18V direct voltage of output, be mainly used in control antenna horizontal/vertical polarization of the e direction; Control commutation circuit: be mainly used in the switching of the two local frequencies of LNB or the switching of alternative controller; LNB voltage switch control circuit: be mainly used in the voltage of opening or turn-offing LNB.For voltage conversion circuit, at present mostly the 22V voltage that provides by the front end power panel adopts the LM317 family chip, thereby thereby utilizes the triode conducting to change its configuration resistance and change its output voltage and export 13V, 18V respectively with turn-offing.For the control commutation circuit, after master chip is exported this AC signal, be modulated on the 13/18V direct voltage by triode.For LNB voltage switch control circuit, LNB voltage switch control signal then is by the unlatching of triode in the switching circuit or turn-offs the operating state of controlling whole switching circuit.
It is inevitable that LNB in use has a situation, that is exactly the interface that antenna need be connected to the set-top box correspondence as the user during at the fitting machine top box, if the part that this moment, the metal core of antenna and the shell of set-top box etc. belonged to the earth touches because of carelessness, the voltage instantaneous short-circuit that causes tens volts is to the earth, thereby the big electric current of instantaneous generation, so from the 22V of power panel output to final this section of antenna output 13/18V circuit, will inevitably burn the device that some can't anti-high electric current, thereby cause the LNB switching circuit can't continue operate as normal even personal injury takes place.The short-circuit protection measure of LNB switching circuit is arisen at the historic moment for this reason.This paper introduces a kind of LNB switching circuit that has the safeguard measure of short circuit.
In the prior art, use the LM317 chip that circuit is controlled in the LNB switching circuit, as shown in Figure 1, this switching circuit supply power voltage is 22V, and LNB switching circuit each several part signal flow is to as follows:
Voltage conversion circuit: when the LNB_H/V signal of LNB control master chip output is high level, the conducting of Q26 triode, be low level at LNB_CUT this moment, under the situation that Q23 ends, by LM317 resistance configuration this moment, the output of LM317 (being the 2pin of U6 among the figure) is about 14V; When the LNB_H/V signal of LNB control master chip output was low level, the Q26 triode ended, and be low level at LNB_CUT this moment, and under the situation that Q23 ends, by LM317 resistance configuration this moment, the output of LM317 (being the 2pin of U6 among the figure) is about 19V.
The control commutation circuit: when the output voltage of LNB control master chip LNB_22K was high level, triode Q25 conducting was so under LNB voltage switch unlatching situation, the 22K signal loading of interchange is to the LNB voltage of direct current; When the output voltage of LNB switching circuit control chip LNB_22K was low level, triode Q25 was by turn-offing, so turn-off the 22K signal that exchanges.
LNB voltage switch control circuit: when the output voltage of LNB control master chip LNB_CUT is high level, triode Q23 conducting, by resistance configuration this moment, LM317 can't normally start (being U6 among the figure), so do not allow LNB voltage normally to pass through; When the output voltage of LNB switching circuit control chip LNB_CUT was low level, triode Q23 ended, and by resistance configuration this moment, the normal startup of LM317 (being U6 among the figure) is so allow LNB voltage normally to pass through.
In the prior art, in the LNB switching circuit, use the LM317 chip circuit to be controlled there are the following problems: when using the LM317 chip, the circuit heating is more serious, needs radiation fin, and so not only influencing the stability of entire circuit work but also taking PCB also increases cost simultaneously.In addition, because the cost of LM317 chip own is higher, virtually, greatly increased the cost of LNB switching circuit.
The utility model content
The utility model makes up a kind of LNB switching circuit of satellite set top box, overcome in the prior art and in the LNB switching circuit, to use the LM317 chip that circuit is controlled to exist cost more expensive, circuit heating simultaneously is more serious, need radiation fin, influence the stability of entire circuit work and take the technical problem in the space of pcb board.
The technical solution of the utility model is: the LNB switching circuit that makes up a kind of satellite set top box, comprise LNB switching circuit control chip, voltage conversion circuit, control commutation circuit, LNB voltage switch control circuit, metal-oxide-semiconductor Q4, the grid G of described metal-oxide-semiconductor Q4 is connected described voltage conversion circuit and described LNB voltage switch control circuit with source S, the drain D of described metal-oxide-semiconductor Q4 meets described control commutation circuit and output voltage LNA_IN.
Further technical scheme of the present utility model is: described voltage conversion circuit comprises NPN triode Q13, PNP triode Q17, unidirectional breakover element D2, first via supply power voltage, the second road supply power voltage, the base stage of the LNB_H/V output termination NPN triode Q13 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q13 connects base stage and the emitter of PNP triode Q17, the emitter of described NPN triode Q17 connects the second road supply power voltage, described first via supply power voltage connects the collector electrode of described NPN triode Q17 through unidirectional breakover element D2, the collector electrode of described NPN triode Q17 meets the source class S of the Q4 of described metal-oxide-semiconductor, the grounded emitter of described NPN triode Q13.
Further technical scheme of the present utility model is: described voltage conversion circuit also comprises divider resistance R109 and R34, the collector electrode of described NPN triode Q13 connects the base stage of PNP triode Q17 by divider resistance R109, by connect the emitter of PNP triode Q17 after the divider resistance R109 again through divider resistance R34.
Further technical scheme of the present utility model is: described first via supply power voltage is 15V.
Further technical scheme of the present utility model is: described the second road supply power voltage is 20V.
Further technical scheme of the present utility model is: described unidirectional breakover element D2 is a diode.
Further technical scheme of the present utility model is: described LNB voltage switch control circuit comprises NPN triode Q15, the base stage of the described NPN triode of the LNB_CUT output termination Q15 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q15 connects grid level G and the source S of described metal-oxide-semiconductor Q4, the grounded emitter of described NPN triode Q15.
Further technical scheme of the present utility model is: described LNB voltage switch control circuit also comprises divider resistance R42 and R29, the collector electrode of described NPN triode Q15 meets the grid level G of described metal-oxide-semiconductor Q4 behind divider resistance R29, connect the source S of described metal-oxide-semiconductor Q4 after divider resistance R29 again behind R42.
Further technical scheme of the present utility model is: described control commutation circuit comprises NPN triode Q12, PNP triode Q14, the base stage of the described NPN triode of the LNB_22K output termination Q12 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q12 connects ground level, emitter and the voltage output end LNA_IN of described PNP triode Q14, the grounded emitter of described NPN triode Q12.
Further technical scheme of the present utility model is: described control commutation circuit also comprises divider resistance R40 and R110, the collector electrode of described NPN triode Q12 connects the base stage of described PNP triode Q14 behind divider resistance R110, meet emitter and the voltage output end LNA_IN of described PNP triode Q14 after divider resistance R110 again behind R40.
Technique effect of the present utility model is: the satellite set top box LNB switching circuit that the utility model makes up has adopted the short-circuit protection measure; in the use during shell short circuit of the metal core of antenna and set-top box; the overcurrent protection function of power panel normally starts; the overcurrent protection function of power panel normally starts, thereby makes whole LNB switching circuit play the effect of short-circuit protection.Satellite set top box LNB switching circuit caloric value of the present utility model is little, and cost is low, and it is little that components and parts take the space of pcb board.
Description of drawings
Fig. 1 is the circuit diagram of the utility model prior art.
Fig. 2 is a circuit diagram of the present utility model.
Embodiment
Below in conjunction with specific embodiment technical solutions of the utility model are further specified:
Embodiment of the present utility model is: the LNB switching circuit that makes up a kind of satellite set top box, comprise LNB switching circuit control chip, voltage conversion circuit 1, control commutation circuit 3, LNB voltage switch control circuit 2, metal-oxide-semiconductor Q4, the source S of described metal-oxide-semiconductor Q4 is connected described voltage conversion circuit 1 and described LNB voltage switch control circuit 2 with grid G, the drain D of described metal-oxide-semiconductor Q4 meets described control commutation circuit 3 and output voltage LNA_IN.
In the utility model, described voltage conversion circuit comprises NPN triode Q13, PNP triode Q17, unidirectional breakover element D2, first via supply power voltage, the second road supply power voltage, divider resistance R109 and R34.The base stage of the LNB_H/V output termination NPN triode Q13 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q13 connects the base stage of PNP triode Q17 by divider resistance R109, connect the emitter of PNP triode Q17 by divider resistance R109 and divider resistance R34, the emitter of described NPN triode Q17 connects the second road supply power voltage, and described the second road supply power voltage is 20V; Described first via supply power voltage connects the collector electrode of described NPN triode Q17 through unidirectional breakover element D2, and described first via supply power voltage is 15V.The collector electrode of described NPN triode Q17 meets the source class S of the Q4 of described metal-oxide-semiconductor, the grounded emitter of described NPN triode Q17.
In the utility model, described LNB voltage switch control circuit comprises NPN triode Q15, divider resistance R42 and R29, the base stage of the described NPN triode of the LNB_CUT output termination Q15 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q15 meets the grid level G of described metal-oxide-semiconductor Q4 behind divider resistance R29, connect the source S of described metal-oxide-semiconductor Q4 after divider resistance R29 again behind R42.
In the utility model, described control commutation circuit comprises NPN triode Q12, PNP triode Q14, divider resistance R40 and R110, the base stage of the described NPN triode of the LNB_22K output termination Q12 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q12 connects ground level, emitter and the voltage output end LNA_IN of described PNP triode Q14, the grounded emitter of described NPN triode Q12.Described control commutation circuit also comprises divider resistance R40 and R110, the collector electrode of described NPN triode Q12 connects the base stage of described PNP triode Q14 behind divider resistance R110, meet emitter and the voltage output end LNA_IN of described PNP triode Q14 after divider resistance R110 again behind R40.
The course of work of the LNB switching circuit of the utility model satellite set top box is: when the output voltage of LNB switching circuit control chip LNB_H/V is high level, triode Q13 conducting, thereby the collector electrode C of Q13 is output as low level, and then triode Q17 conducting, so the second road voltage 20V flows through Q17, because the existence of unidirectional breakover element D2, first via voltage 15V can't pass through, under the situation that LNB_CUT does not turn-off, from about the about 18V of voltage of LNA_IN output; When the output voltage of LNB switching circuit control chip LNB_H/V is low level, triode Q13 turn-offs, thereby the collector electrode C of Q13 is output as high level, and then triode Q17 turn-offs, so the second road voltage 20V voltage can't flow through Q17, because the existence of the unidirectional conduction of unidirectional breakover element D2, first via voltage 15V passes through smoothly, under the situation that LNB_CUT does not turn-off, from about the about 13V of voltage of LNA_IN output.Described voltage conversion circuit uses by the selection to the first via voltage and the second road voltage, obtains the voltage of 13V and 18V respectively, and this is mainly used in control antenna horizontal/vertical polarization of the e direction.
When the output voltage of LNB switching circuit control chip LNB_CUT is high level, triode Q15 conducting, thereby the collector electrode C of Q15 is output as low level, dividing potential drop by R42 and R29, make the grid G of metal-oxide-semiconductor Q4 and the conducting voltage that the voltage between source class S satisfies this metal-oxide-semiconductor, thereby allow LNB voltage normally to pass through; When the output voltage of LNB switching circuit control chip LNB_CUT is low level, triode Q15 ends, thereby the collector electrode C of Q15 is output as high level, cause the grid G of metal-oxide-semiconductor Q4 and the voltage between source class S not to satisfy the conducting voltage of this metal-oxide-semiconductor, do not allow LNB voltage normally to pass through thereby block.
When the output voltage of LNB switching circuit control chip LNB_22K is high level, triode Q12 conducting, thereby the collector electrode C output low level of Q12, and then triode Q14 conducting, so under LNB voltage switch unlatching situation, the 22K signal loading of interchange is to the LNB voltage of direct current; When the output voltage of LNB switching circuit control chip LNB_22K was low level, triode Q12 was by shutoff, thus the collector electrode C of Q12 output high level, and then triode Q14 is by turn-offing, so turn-off the 22K signal of interchange.
During the LNA_IN output short-circuit, signal is by main line circulation among the figure when LNB switching circuit output short-circuit.Metal-oxide-semiconductor Q4 works in magnifying state, resistance that can a high value of equivalence, thereby on the whole main line electric current very little be a microampere rank, can ignore substantially.But event triode Q13 is operate as normal still, and through about 80ms, the overcurrent protection function of power panel normally starts, thereby makes whole LNB switching circuit play the effect of short-circuit protection.
Above content be in conjunction with concrete preferred implementation to further describing that the utility model is done, can not assert that concrete enforcement of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field, under the prerequisite that does not break away from the utility model design, can also make some simple deduction or replace, all should be considered as belonging to protection range of the present utility model.
Claims (10)
1. the LNB switching circuit of a satellite set top box, comprise LNB switching circuit control chip, voltage conversion circuit, control commutation circuit, LNB voltage switch control circuit, it is characterized in that, also comprise metal-oxide-semiconductor Q4, the grid G of described metal-oxide-semiconductor Q4 is connected described voltage conversion circuit and described LNB voltage switch control circuit with source S, the drain D of described metal-oxide-semiconductor Q4 meets described control commutation circuit and output voltage LNA_IN.
2. the LNB switching circuit of satellite set top box according to claim 1, it is characterized in that, described voltage conversion circuit comprises NPN triode Q13, PNP triode Q17, unidirectional breakover element D2, first via supply power voltage, the second road supply power voltage, the base stage of the LNB_H/V output termination NPN triode Q13 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q13 connects base stage and the emitter of PNP triode Q17, the emitter of described NPN triode Q17 connects the second road supply power voltage, described first via supply power voltage connects the collector electrode of described NPN triode Q17 through unidirectional breakover element D2, the collector electrode of described NPN triode Q17 meets the source class S of the Q4 of described metal-oxide-semiconductor, the grounded emitter of described NPN triode Q13.
3. the LNB switching circuit of satellite set top box according to claim 2, it is characterized in that, described voltage conversion circuit also comprises divider resistance R109 and R34, the collector electrode of described NPN triode Q13 connects the base stage of PNP triode Q17 by divider resistance R109, by connect the emitter of PNP triode Q17 after the divider resistance R109 again through divider resistance R34.
4. the LNB switching circuit of satellite set top box according to claim 2 is characterized in that, described first via supply power voltage is 15V.
5. the LNB switching circuit of satellite set top box according to claim 2 is characterized in that, described the second road supply power voltage is 20V.
6. the LNB switching circuit of satellite set top box according to claim 2 is characterized in that, described unidirectional breakover element D2 is a diode.
7. the LNB switching circuit of satellite set top box according to claim 1, it is characterized in that, described LNB voltage switch control circuit comprises NPN triode Q15, the base stage of the described NPN triode of the LNB_CUT output termination Q15 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q15 connects grid level G and the source S of described metal-oxide-semiconductor Q4, the grounded emitter of described NPN triode Q15.
8. the LNB switching circuit of satellite set top box according to claim 7, it is characterized in that, described LNB voltage switch control circuit also comprises divider resistance R42 and R29, the collector electrode of described NPN triode Q15 meets the grid level G of described metal-oxide-semiconductor Q4 behind divider resistance R29, connect the source S of described metal-oxide-semiconductor Q4 after divider resistance R29 again behind R42.
9. the LNB switching circuit of satellite set top box according to claim 1, it is characterized in that, described control commutation circuit comprises NPN triode Q12, PNP triode Q14, the base stage of the described NPN triode of the LNB_22K output termination Q12 of described LNB switching circuit control chip, the collector electrode of described NPN triode Q12 connects ground level, emitter and the voltage output end LNA_IN of described PNP triode Q14, the grounded emitter of described NPN triode Q12.
10. the LNB switching circuit of satellite set top box according to claim 9, it is characterized in that, described control commutation circuit also comprises divider resistance R40 and R110, the collector electrode of described NPN triode Q12 connects the base stage of described PNP triode Q14 behind divider resistance R110, meet emitter and the voltage output end LNA_IN of described PNP triode Q14 after divider resistance R110 again behind R40.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202058389U CN201533345U (en) | 2009-10-22 | 2009-10-22 | LNB switching circuit of satellite set-top box |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202058389U CN201533345U (en) | 2009-10-22 | 2009-10-22 | LNB switching circuit of satellite set-top box |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201533345U true CN201533345U (en) | 2010-07-21 |
Family
ID=42528744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009202058389U Expired - Fee Related CN201533345U (en) | 2009-10-22 | 2009-10-22 | LNB switching circuit of satellite set-top box |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201533345U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888183A (en) * | 2010-07-28 | 2010-11-17 | 鸿富锦精密工业（深圳）有限公司 | Switch power circuit and electronic equipment |
| CN102811327A (en) * | 2011-06-02 | 2012-12-05 | 深圳市视维科技有限公司 | LNB (Low Noise Block) power supply control circuit in digital television set top box |
| CN103227943A (en) * | 2013-04-15 | 2013-07-31 | 深圳创维数字技术股份有限公司 | Protection method, equipment and system of set top box |
| CN109617403A (en) * | 2018-12-13 | 2019-04-12 | 珠海迈科智能科技股份有限公司 | A kind of LNB chip |
-
2009
- 2009-10-22 CN CN2009202058389U patent/CN201533345U/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888183A (en) * | 2010-07-28 | 2010-11-17 | 鸿富锦精密工业（深圳）有限公司 | Switch power circuit and electronic equipment |
| CN101888183B (en) * | 2010-07-28 | 2013-03-20 | 鸿富锦精密工业（深圳）有限公司 | Switch power circuit and electronic equipment |
| CN102811327A (en) * | 2011-06-02 | 2012-12-05 | 深圳市视维科技有限公司 | LNB (Low Noise Block) power supply control circuit in digital television set top box |
| CN102811327B (en) * | 2011-06-02 | 2016-02-10 | 深圳市视维科技有限公司 | Digital TV set-top box LNB power-supplying circuit |
| CN103227943A (en) * | 2013-04-15 | 2013-07-31 | 深圳创维数字技术股份有限公司 | Protection method, equipment and system of set top box |
| CN103227943B (en) * | 2013-04-15 | 2016-08-24 | 深圳创维数字技术有限公司 | The guard method of a kind of Set Top Box, equipment and system |
| CN109617403A (en) * | 2018-12-13 | 2019-04-12 | 珠海迈科智能科技股份有限公司 | A kind of LNB chip |
| CN109617403B (en) * | 2018-12-13 | 2021-01-29 | 珠海迈科智能科技股份有限公司 | LNB chip |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN201533345U (en) | LNB switching circuit of satellite set-top box | |
| CN202396132U (en) | Fan radiating control circuit and television | |
| CN204144917U (en) | A kind of overvoltage crowbar | |
| CN203326653U (en) | Solar energy storage battery charging circuit | |
| CN106301332A (en) | Circuit for the electric discharge of delay startup current supply circuit | |
| CN106532867A (en) | Charging circuit and mobile terminal | |
| CN205004952U (en) | Direct current soft start circuit | |
| CN206077347U (en) | Numeric type IGBT is controlled and driving means | |
| CN109613968A (en) | Power supply redundant output circuit with short-circuit protection | |
| CN201039316Y (en) | A reset circuit and TV set with above reset circuit | |
| CN205960636U (en) | Surge current control circuit and power supply unit | |
| CN105045365A (en) | Power supply adapter board and method and system for controlling output current of power supply adapter board | |
| CN109347315B (en) | Power-on buffer circuit of power electronic device | |
| CN101552452A (en) | Short-circuit protection circuit for switching power supply of frequency converter | |
| CN209046523U (en) | Power-on and power-off sequencing circuit and electronic equipment | |
| CN104423519B (en) | Mainboard power supply system | |
| CN202978910U (en) | Digital satellite receiver and LNB power supply control circuit thereof | |
| CN110086408A (en) | Solar power system | |
| CN206099293U (en) | High voltage input protection circuit | |
| CN202153707U (en) | Power supply module and power supply system | |
| CN205880720U (en) | Protection circuit and power adapter of chip | |
| CN108429237B (en) | A kind of hardware protection circuit of electric machine controller | |
| CN202217199U (en) | Power supply module and power supply system | |
| CN207053651U (en) | A kind of circuit and television set for reducing television standby power consumption | |
| CN206595885U (en) | Power supply electric appliance function expansion module |
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 |
Granted publication date: 20100721 Termination date: 20151022 |
|
| EXPY | Termination of patent right or utility model |