CN102811327A - LNB (Low Noise Block) power supply control circuit in digital television set top box - Google Patents
LNB (Low Noise Block) power supply control circuit in digital television set top box Download PDFInfo
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- CN102811327A CN102811327A CN2011101471978A CN201110147197A CN102811327A CN 102811327 A CN102811327 A CN 102811327A CN 2011101471978 A CN2011101471978 A CN 2011101471978A CN 201110147197 A CN201110147197 A CN 201110147197A CN 102811327 A CN102811327 A CN 102811327A
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Abstract
The invention discloses an LNB (Low Noise Block) power supply control circuit in a digital television. The set top box LNB power supply control circuit comprises an LNB power supply switch circuit, a voltage switching circuit, a 22KHz square wave control circuit and an LNB power supply circuit. A diode, a triode, a resistor and a capacitor are only used in the LNB power supply control circuit in the digital television set top box, the function of switching two voltages of 13V and 18V is achieved; and the LNB power supply control circuit has functions of power supply overload protection and 22KHz square wave signal switching.
Description
[technical field]
The present invention relates to DTV STB, relate in particular to the LNB power-supplying circuit of DTV STB.
[background technology]
Top box of digital machine is controlled tuner through coaxial cable when receiving signal, is used to two kinds of switchable supply power voltages from the 13/18V of STB, confirms that desired signal is horizontal polarization signal or perpendicular polarization signal.Tradition LNB power-supplying circuit is core with LM317, through the adjusting control to LM317, makes two kinds of constant voltages of LNB power-supplying circuit output 13/18V, and this circuit design is ripe, has been LNB power-supplying circuit the most frequently used in all kinds of top box of digital machines.
Fig. 2 is the LNB power-supplying circuit of core for Traditional use LM317, and said circuit comprises 22K square wave control circuit (1), LNB voltage commutation circuit (2), LNB power supply voltage stabilizing circuit (3) and LNB power switch circuit (4).
LNB power supply voltage stabilizing circuit (3) comprises electrochemical capacitor EC7, three-terminal voltage-stabilizing device LM317, resistance R 57, resistance R 58.The application sketch map of three-terminal voltage-stabilizing device LM317 is as shown in Figure 3; Its power input links to each other with the 22V constant voltage; Its power output end links to each other with the voltage output end 13/18V of LNB with diode D19 through resistance R 56, and its adjustment end links to each other with the middle triode Q11 collector electrode of LNB power switch circuit (4).When three-terminal voltage-stabilizing device LM317 imports a stable voltage 22V,, just can export corresponding different burning voltage at the LM317 output through the resistance of sampling resistor over the ground of its adjustment end of CPU control.
LNB power switch circuit (4) is connected with power switch signal end ON/OFF, and LNB power switch circuit 4 comprises resistance R 46, resistance R 54, resistance R 56, resistance R 23, triode Q11 and triode Q12.Triode Q11 base stage links to each other with power switch signal end ON/OFF through resistance R 46, its grounded emitter, and its collector electrode links to each other with the adjustment end of three-terminal voltage-stabilizing device LM317 in the LNB power supply circuits 3.Triode Q12 base stage links to each other with diode D19 anode through resistance R 54, and its emitter links to each other with the output of LM317 in the LNB power supply circuits (3), and its collector electrode links to each other with triode Q11 base stage through resistance R 23.
LNB voltage commutation circuit (2) comprises resistance R 47, resistance R 60 and triode Q10.Said triode Q10 base stage links to each other with voltage switching signal end through resistance R 47, its grounded emitter, and its collector electrode links to each other with the adjustment end of three-terminal voltage-stabilizing device LM317 in the LNB power supply circuits 3 through resistance R 60.When voltage signal end input high level, triode Q10 conducting, when voltage signal end input low level, triode Q10 ends.
Square wave control circuit (1) comprises resistance R 43, resistance R 42, resistance R 41, triode Q9, capacitor C 47.Frequency is that the square-wave signal of 22KHz is provided by CPU, through control triode Q9, makes the square-wave signal of a 22KHz of stack on the LNB voltage.
As stated, in traditional DTV STB LNB power-supplying circuit, three-terminal voltage-stabilizing device LM317 is adopted in the core, through the control to it, makes the different burning voltage of its output.Because three-terminal voltage-stabilizing device LM317 cost is higher, makes that the cost of corresponding product is higher.
[summary of the invention]
The technical problem that the present invention will solve is, to the above-mentioned defective of conventional art, a kind of LNB power-supplying circuit is provided; Through using diode, triode resistance and electric capacity; Realize switchable 13/18V voltage output, the function that overload protection and 22KHz square-wave signal switch reduces cost.
To achieve these goals; The technical scheme that the present invention adopts is: the LNB in a kind of DTV is provided power-supplying circuit; Said circuit comprises LNB power switch circuit, voltage commutation circuit, square wave control circuit and the LNB power supply circuits with power supply overload protection function, also comprises switching signal end LNB_ON/OFF, voltage switching signal end and square-wave signal end.
In LNB power switch circuit of the present invention; When power switch signal end LNB_ON/OFF output high level; Triode Q5 conducting, and then control triode Q4 conducting finally make the LNB power supply close; When power switch signal end LNB_ON/OFF output low level, then finally make the burning voltage that two kinds of LNB outputs can be optional; In the LNB power supply process, when the pressure drop on the resistance R 1 surpasses the conducting voltage of triode Q4, triode Q4 conducting, thus cause triode Q1 to end, the LNB power supply is closed, and this part circuit has played the power supply overload protective function.
In voltage commutation circuit of the present invention, triode Q6 base stage is connected with voltage switching signal end through resistance R 302, its grounded emitter, and its collector electrode is connected with triode Q7 base stage through resistance R 319; Triode Q7 collector electrode is connected with the 19V constant voltage, and its collector electrode is through capacitor C 330 ground connection; Diode D301, its anode is connected with the 14V constant voltage, and its negative electrode is through capacitor C 330 ground connection; When voltage switching signal end output high level, voltage commutation circuit (7) output 19V constant voltage, when voltage switching signal end output low level, said voltage commutation circuit (7) output 14V constant voltage.
In LNB voltage control circuit of the present invention, two kinds of constant voltages of 14/19V of voltage commutation circuit (7) output, through tool diode D1, the output at LNB power supply circuits 9 behind the step-down 1V is exported two kinds of constant voltages of 13/18V.
In square wave control circuit of the present invention, triode Q3 base stage is connected with the square-wave signal end through resistance R 301, its grounded emitter, and its collector electrode links to each other with triode Q2 base stage through resistance R 308; The emitter of triode Q2 links to each other with diode D1 anode, and its collector electrode links to each other with diode D1 negative electrode; The square-wave signal of 22KHz is provided by CPU, through triode Q3 control triode Q2 conducting repeatedly, end, thereby makes the square-wave signal of a 22KHz of stack on the LNB voltage.
The present invention compares with conventional art; Beneficial effect is: the LNB power-supplying circuit in the DTV STB of the present invention only uses diode, triode, resistance and electric capacity; Reach two kinds of electricity of output 13/18V, power supply overload protection and 22KHz square-wave signal handoff functionality, reduced cost than conventional art.
[description of drawings]
Fig. 1 is the sketch map of DTV STB LNB power-supplying circuit of the present invention.
Fig. 2 is for using traditional LNB power supply circuits sketch map of LM317.
Fig. 3 is the application sketch map of three-terminal voltage-stabilizing device LM317.
[embodiment]
As shown in Figure 1, DTV STB LNB power-supplying circuit of the present invention comprises LNB switching circuit of power supply (6), overload detection circuit (8) voltage commutation circuit (7), square wave control circuit (9).The output of voltage commutation circuit (7) links to each other with 22KHz square wave control circuit said overload detection circuit (8), said (9), said LNB switching circuit of power supply (6) successively.
Said LNB switching circuit of power supply (6) with power supply overload protection function comprises resistance R 303, resistance R 304, resistance 305, resistance R 306, diode D303, triode Q1 and triode Q5; Said overload detection circuit (8) comprises resistance R 1, resistance R 318, triode Q4.The base stage of triode Q5 links to each other with power switch signal end LNB_ON/OFF through resistance R 304, its grounded emitter, and its collector electrode links to each other with said triode Q4 base stage through resistance R 305; When power switch signal end LNB_ON/OFF output high level, triode Q5 conducting, and then control triode Q4 conducting; Diode D303 conducting makes the Q1 base voltage be higher than emitter voltage, and Q1 ends; The LNB power supply is closed; When power switch signal end LNB_ON/OFF output low level, the LNB power-supplying circuit is in power supply state, two kinds of optional burning voltages of final LNB power-supplying circuit output; In the LNB power supply process, when the pressure drop on the resistance R 1 surpasses the conducting voltage of triode Q4, triode Q4 conducting, thus cause triode Q1 to end, the LNB power supply is closed, and this part circuit has played the power supply overload protective function.
Voltage commutation circuit (7) comprises resistance R 302, resistance R 319, diode D301, triode Q6, triode Q7; Said triode Q6 base stage is connected with voltage switching signal end through resistance R 302, its grounded emitter, and its collector electrode is connected with said triode Q7 base stage through resistance R 319; Said triode Q7 collector electrode is connected with the 19V constant voltage, and its collector electrode is connected to filter capacitor C330; Said diode D301, its anode is connected with the 14V constant voltage, and its negative electrode links to each other with triode Q7 collector electrode; When voltage switching signal end output high level, said voltage commutation circuit (7) output 19V constant voltage, when voltage switching signal end output low level, said voltage commutation circuit (7) output 14V constant voltage.Two kinds of constant voltages of 14/19V of said voltage commutation circuit (7) output, the diode D1 in said 22K square wave control circuit (9), the output at said LNB power supply circuits (9) behind the step-down 1V is exported two kinds of constant voltages of 13/18V.
Square wave control circuit (9) comprises resistance R 301, resistance R 308, diode D1, triode Q2 and triode Q3; Said triode Q3 base stage is connected with the square-wave signal end through resistance R 301, its grounded emitter, and its collector electrode links to each other with triode Q2 base stage through resistance R 308; The emitter of said triode Q2 links to each other with diode D1 anode, and its collector electrode links to each other with diode D1 negative electrode; The square-wave signal of 22KHz is provided by CPU, through triode Q3 control triode Q2 conducting repeatedly, end, thereby makes the square-wave signal of a 22KHz of stack on the LNB voltage.
The above is merely preferable embodiment of the present invention, not in order to restriction the present invention, any modification of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (4)
1. DTV STB LNB power-supplying circuit; Comprise LNB switching circuit of power supply (6), voltage commutation circuit (7), overload detection circuit (8), 22KHz square wave control circuit (9), also comprise switching signal end LNB_ON/OFF, voltage switching signal end and square-wave signal end with power supply overload protection function; It is characterized in that the output of said voltage commutation circuit (7) links to each other with 22K square wave control circuit said overload detection circuit (8), said (9), said LNB switching circuit of power supply (6) successively.
2. a kind of DTV STB LNB power-supplying circuit as claimed in claim 1; It is characterized in that said LNB switching circuit of power supply (6) with power supply overload protection function comprises resistance R 303, resistance R 304, resistance 305, resistance R 306, diode D303, triode Q1 and triode Q5; Said overload detection circuit (8) comprises resistance R 1, resistance R 318, triode Q4.The base stage of said triode Q5 links to each other with power switch signal end LNB_ON/OFF through resistance R 304, its grounded emitter, and its collector electrode links to each other with said triode Q4 base stage through resistance R 305; When power switch signal end LNB_ON/OFF output high level, triode Q5 conducting, and then control triode Q4 conducting; Diode D303 conducting makes the Q1 base voltage be higher than emitter voltage, and Q1 ends; The LNB power supply is closed; When power switch signal end LNB_ON/OFF output low level, the LNB power-supplying circuit is in power supply state, two kinds of optional burning voltages of final LNB power-supplying circuit output; In the LNB power supply process, when the pressure drop on the resistance R 1 surpasses the conducting voltage of triode Q4, triode Q4 conducting, thus cause triode Q1 to end, the LNB power supply is closed, and this part circuit has played the power supply overload protective function.
3. a kind of DTV STB LNB power-supplying circuit as claimed in claim 1 is characterized in that said voltage commutation circuit (7) comprises resistance R 302, resistance R 319, diode D301, triode Q6, triode Q7; Said triode Q6 base stage is connected with voltage switching signal end through resistance R 302, its grounded emitter, and its collector electrode is connected with said triode Q7 base stage through resistance R 319; Said triode Q7 collector electrode is connected with the 19V constant voltage, and its collector electrode is connected to filter capacitor C330; Said diode D301, its anode is connected with the 14V constant voltage, and its negative electrode links to each other with triode Q7 collector electrode; When voltage switching signal end output high level, said voltage commutation circuit (7) output 19V constant voltage, when voltage switching signal end output low level, said voltage commutation circuit (7) output 14V constant voltage.Two kinds of constant voltages of 14/19V of said voltage commutation circuit (7) output, the diode D1 in said 22K square wave control circuit (9), the output at said LNB power supply circuits (9) behind the step-down 1V is exported two kinds of constant voltages of 13/18V.
4. a kind of DTV STB LNB power-supplying circuit as claimed in claim 1 is characterized in that said square wave control circuit (9) comprises resistance R 301, resistance R 308, diode D1, triode Q2 and triode Q3; Said triode Q3 base stage is connected with the square-wave signal end through resistance R 301, its grounded emitter, and its collector electrode links to each other with triode Q2 base stage through resistance R 308; The emitter of said triode Q2 links to each other with diode D1 anode, and its collector electrode links to each other with diode D1 negative electrode; The square-wave signal of 22KHz is provided by CPU, through triode Q3 control triode Q2 conducting repeatedly, end, thereby makes the square-wave signal of a 22KHz of stack on the LNB voltage.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110147197.8A CN102811327B (en) | 2011-06-02 | 2011-06-02 | Digital TV set-top box LNB power-supplying circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110147197.8A CN102811327B (en) | 2011-06-02 | 2011-06-02 | Digital TV set-top box LNB power-supplying circuit |
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| CN102811327A true CN102811327A (en) | 2012-12-05 |
| CN102811327B CN102811327B (en) | 2016-02-10 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| 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 |
| CN104254008A (en) * | 2014-09-16 | 2014-12-31 | 深圳市九洲电器有限公司 | LNB loop polarization voltage switching control circuit and device |
| CN106454171A (en) * | 2016-11-15 | 2017-02-22 | 深圳市视维科技有限公司 | Power supply circuit of CA card of set-top-box |
| CN107197184A (en) * | 2017-07-05 | 2017-09-22 | 青岛海信电器股份有限公司 | A kind of supplying power for tuner control circuit, system and top box of digital machine |
| 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 |
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| CN202095020U (en) * | 2011-06-02 | 2011-12-28 | 深圳市视维科技有限公司 | Low noise block (LNB) power supply control circuit of digital television set top box |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN104254008A (en) * | 2014-09-16 | 2014-12-31 | 深圳市九洲电器有限公司 | LNB loop polarization voltage switching control circuit and device |
| WO2016041417A1 (en) * | 2014-09-16 | 2016-03-24 | 深圳市九洲电器有限公司 | Circuit and device for controlling lnb loop polarization voltage switching |
| CN104254008B (en) * | 2014-09-16 | 2017-11-07 | 深圳市九洲电器有限公司 | A kind of LNB rings wear polarizing voltage control switching circuit and device |
| CN106454171A (en) * | 2016-11-15 | 2017-02-22 | 深圳市视维科技有限公司 | Power supply circuit of CA card of set-top-box |
| CN107197184A (en) * | 2017-07-05 | 2017-09-22 | 青岛海信电器股份有限公司 | A kind of supplying power for tuner control circuit, system and top box of digital machine |
| 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 |
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| CN102811327B (en) | 2016-02-10 |
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Address after: 518000 Guangdong city of Shenzhen province Nanshan District Yuquanlu Road Yizhe building 7 floor East Patentee after: Shenzhen AOK Polytron Technologies Inc Address before: 518000 Guangdong city of Shenzhen province Nanshan District Yuquanlu Road Yizhe building 7 floor Patentee before: Shenzhen Sowell Technology Co., Ltd. |
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Effective date of registration: 20201029 Address after: 518000 second floor, No.18, Xiaoshan North Road, Xinsheng community, Longgang street, Longgang District, Shenzhen City, Guangdong Province Patentee after: Shenzhen Lingxiu Global Technology Co., Ltd Address before: 518000 Guangdong city of Shenzhen province Nanshan District Yuquanlu Road Yizhe building 7 floor East Patentee before: SHENZHEN SVI TECHNOLOGY Co.,Ltd. |
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Granted publication date: 20160210 Termination date: 20210602 |