CN201528381U - Set-top box on-off mute circuit - Google Patents
Set-top box on-off mute circuit Download PDFInfo
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- CN201528381U CN201528381U CN2009201834787U CN200920183478U CN201528381U CN 201528381 U CN201528381 U CN 201528381U CN 2009201834787 U CN2009201834787 U CN 2009201834787U CN 200920183478 U CN200920183478 U CN 200920183478U CN 201528381 U CN201528381 U CN 201528381U
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Abstract
The utility model relates to a set-top box on-off mute circuit, which comprises three common emitter circuits and a common-base circuit, wherein a first common emitter circuit, the common-base circuit, a second common emitter circuit and a third emitter circuit are connected sequentially. Based on a common mute circuit, the set-top box on-off mute circuit realizes on-off mute and increases product performance by aids of a simple triode and a resistance-capacitance circuit.
Description
[technical field]
The utility model belongs to the digital TV set-top box field, specifically is meant the set-top box mute circuit for open and close.
[background technology]
Along with the digitized process of national TV signal, Digital Television has entered into huge numbers of families, and digital TV set-top box plays an important role in the popularization of Digital Television.
As a kind of emerging home electronics, the function of set-top box is quite perfect, can realize many functions, comprises the mute function of watching process.But prior art all is to realize quiet effect after start, in the start process because amplifier powers on the start sonic boom that produces have no idea to carry out good restraining.
Fig. 1 is existing common mute circuit.Form by two cascode level circuit.When set-top box is used, the MUTE output low level, NPN triode QA4, QA5 end, not conducting of circuit, the set-top box sound channel is normally exported.When the set-top box needs were quiet, MUTE exported high level, NPN triode QA4, QA5 conducting, and left and right sound track signals L_CH, R_CH ground connection, circuit is realized quiet.
Prior art can't suppress in the start process start sonic boom that causes because power on.
[utility model content]
Technical problem to be solved in the utility model is to provide a kind of set-top box mute circuit for open and close quiet can realize switching on and shutting down the time.
The utility model solves the problems of the technologies described above by the following technical solutions:
The set-top box mute circuit for open and close comprises three cascode level circuit and a common-base circuit; Wherein the first cascode level circuit, common-base circuit, the second cascode level circuit, the 3rd cascode level circuit connect successively;
The first cascode level circuit comprises one the one NPN triode, a pull-up resistor, one first current-limiting resistance, and wherein the base stage of a NPN three utmost points is connected to the MUTE end by described first current-limiting resistance, and collector electrode is connected to described grounded base circuit, grounded emitter; Described pull-up resistor is connected between 3.3V power supply and the MUTE end;
Common-base circuit comprises a PNP triode, the first current limliting divider resistance, the second current limliting divider resistance, diode, a charge and discharge capacitance; Wherein the PNP transistor base is connected to first common emitter circuit by the first current limliting divider resistance, collector electrode is connected to second common emitter circuit, emitter is connected to the 12V power supply by diode, and the PNP transistor base also is connected to the 12V power supply by the second current limliting divider resistance; Charge and discharge capacitance connects between PNP transistor emitter and the ground;
The second cascode level circuit comprises one the 2nd NPN triode, second current-limiting resistance; The base stage of the 2nd NPN triode is connected to described common-base circuit by second current-limiting resistance, grounded emitter, and collector electrode is connected to R channel;
The 3rd cascode level circuit comprises one the 3rd NPN triode, the 3rd current-limiting resistance; The base stage of the 3rd NPN triode is connected to described common-base circuit by the 3rd current-limiting resistance, grounded emitter, and collector electrode is connected to L channel.
A described NPN triode, the 2nd NPN triode, the 3rd NPN triode model are 2SC1815.
Described PNP triode model is 2N2907.
Described diode model is 1N4148.
Advantage of the present utility model is: on the basis of common mute circuit, by simple triode and resistance-capacitance circuit, realized turn-on muting, improved properties of product.
[description of drawings]
The utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is set-top box mute circuit figure in the prior art.
Fig. 2 is the utility model circuit diagram.
[embodiment]
See also shown in Figure 2ly, the set-top box mute circuit for open and close comprises three cascode level circuit and a common-base circuit; Wherein the first cascode level circuit 1, common-base circuit 2, the second cascode level circuit 3, the 3rd cascode level circuit 4 connect successively;
The first cascode level circuit 1 comprises NPN triode QA3, pull-up resistor, current-limiting resistance, and wherein the base stage of this NPN triode QA3 is connected to the MUTE end by current-limiting resistance RA20, and collector electrode is connected to grounded base circuit 2, grounded emitter; Pull-up resistor RA19 is connected between 3.3V power supply and the MUTE end;
Common-base circuit 2 comprises PNP triode QA7, current limliting divider resistance RA21, current limliting divider resistance RA22, diode DA3, charge and discharge capacitance CA11; Wherein PNP triode QA7 base stage is connected to first common emitter circuit 1 by current limliting divider resistance RA21, collector electrode is connected to second common emitter circuit 3, emitter is connected to the 12V power supply by diode DA3, and PNP triode QA7 base stage also is connected to the 12V power supply by current limliting divider resistance RA22; Charge and discharge capacitance CA11 connects between PNP triode QA7 emitter and the ground;
The second cascode level circuit 3 comprises NPN triode QA2, current-limiting resistance RA24; The base stage of NPN triode QA2 is connected to common-base circuit 2 by current-limiting resistance RA24, grounded emitter, and collector electrode is connected to R channel R_CH;
The 3rd cascode level circuit 4 comprises NPN triode QA1, current-limiting resistance RA23; The base stage of NPN triode QA1 is connected to common-base circuit 2 by current-limiting resistance RA23, grounded emitter, and collector electrode is connected to L channel L_CH.
NPN triode QA1, NPN triode QA2, NPN triode QA3 model are 2SC1815.
PNP triode QA7 model is 2N2907.Diode DA3 model is 1N4148.
The base stage of NPN triode QA3 connects draws resistance R A19, and the NPN transistor base was a high level when set-top box normally powered on, NPN triode QA3 conducting this moment, and the collector voltage of NPN triode QA3 is 0.7V.Under the dividing potential drop effect of current-limiting resistor voltage divider RA21, RA22, the base voltage Vb=(12-0.7) of PNP triode QA7 * RA21/ (RA21+RA22)+0.7=6.35V.And the transmitter of PNP triode QA7 meets positive supply 12V, then PNP triode QA7 conducting, and collector voltage is pressed reason because of the conducting economize on electricity of diode DA3 and PNP triode QA7, for about 10.4V.Again because the emitter junction ground connection of NPN triode QA1, NPN triode QA2, thus NPN triode QA1, NPN triode QA2 conducting, left and right sound track signals L_CH, R_CH ground connection, circuit plays the quiet effect that powers on.
When the set-top box operate as normal, by dragging down the pin of MUTE, NPN triode QA3 ends, and not conducting of circuit can realize the left and right acoustic channels output of set-top box.
The utility model design is to be optimized on the basis of common mute circuit, can effectively eliminate the sonic boom of set-top box in start process, promotes properties of product, improves the competitiveness of product in market.
Claims (4)
1. the set-top box mute circuit for open and close is characterized in that: comprise three cascode level circuit and a common-base circuit; Wherein the first cascode level circuit, common-base circuit, the second cascode level circuit, the 3rd cascode level circuit connect successively;
The described first cascode level circuit comprises one the one NPN triode, a pull-up resistor, one first current-limiting resistance, wherein the base stage of a NPN three utmost points is connected to the MUTE end by described first current-limiting resistance, collector electrode is connected to described grounded base circuit, grounded emitter; Described pull-up resistor is connected between 3.3V power supply and the MUTE end;
Described common-base circuit comprises a PNP triode, the first current limliting divider resistance, the second current limliting divider resistance, diode, a charge and discharge capacitance; Wherein the PNP transistor base is connected to first common emitter circuit by the first current limliting divider resistance, collector electrode is connected to second common emitter circuit, emitter is connected to the 12V power supply by diode, and the PNP transistor base also is connected to the 12V power supply by the second current limliting divider resistance; Charge and discharge capacitance connects between PNP transistor emitter and the ground;
The described second cascode level circuit comprises one the 2nd NPN triode, second current-limiting resistance; The base stage of the 2nd NPN triode is connected to described common-base circuit by second current-limiting resistance, grounded emitter, and collector electrode is connected to R channel;
Described the 3rd cascode level circuit comprises one the 3rd NPN triode, the 3rd current-limiting resistance; The base stage of the 3rd NPN triode is connected to described common-base circuit by the 3rd current-limiting resistance, grounded emitter, and collector electrode is connected to L channel.
2. set-top box mute circuit for open and close as claimed in claim 1 is characterized in that: a described NPN triode, the 2nd NPN triode, the 3rd NPN triode model are 2SC1815.
3. set-top box mute circuit for open and close as claimed in claim 1 is characterized in that: described PNP triode model is 2N2907.
4. set-top box mute circuit for open and close as claimed in claim 1 is characterized in that: described diode model is 1N4148.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009201834787U CN201528381U (en) | 2009-10-28 | 2009-10-28 | Set-top box on-off mute circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009201834787U CN201528381U (en) | 2009-10-28 | 2009-10-28 | Set-top box on-off mute circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201528381U true CN201528381U (en) | 2010-07-14 |
Family
ID=42519662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009201834787U Expired - Fee Related CN201528381U (en) | 2009-10-28 | 2009-10-28 | Set-top box on-off mute circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201528381U (en) |
-
2009
- 2009-10-28 CN CN2009201834787U patent/CN201528381U/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee | ||
| CP03 | Change of name, title or address |
Address after: Mawei Development Zone, Fujian province Fuzhou Ru Jiang Road 350000, No. 70 (Scud Industrial Park) 6 floor and 5 floor two to four Patentee after: Fujian Newland Communication Science Technology Co., Ltd. Address before: 350000 Fuzhou Province, Mawei District, west of the Confucian Road, No. 1 Patentee before: Fujian Newland Communication Science & Technology Co., Ltd. |
|
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20100714 Termination date: 20131028 |