CN2730049Y

CN2730049Y - Buffer circuit on IIC bus of TV. set

Info

Publication number: CN2730049Y
Application number: CNU2004200971002U
Authority: CN
Inventors: 孙士华; 李磊; 肖龙光; 高红满
Original assignee: Hisense Group Co Ltd; Qingdao Hisense Electronics Co Ltd
Current assignee: Hisense Group Co Ltd; Qingdao Hisense Electronics Co Ltd
Priority date: 2004-10-14
Filing date: 2004-10-14
Publication date: 2005-09-28
Anticipated expiration: 2014-10-14

Abstract

The utility model provides an isolating circuit on IIC bus of a television set which belongs to a circuit technical field of the television set. The isolating circuit consists of gating switches between power down IC components and no-power down IC components on the IIC bus. The isolating circuit adopts two MOS field-effect tubes whose 3 feet are respectively connected with terminals of D-SDA and D-SCL. 1 foot is respectively connected with the terminals of the SDA and the SCL on the IIC bus. While 2 feet are connected with controlling power circuits 5VS of a single-chip microcomputer. The models of the two MOS field-effect tubes are RK7002T116. The isolating circuit causes the power down components and the no-power down components on the IIC bus to be mutually isolated, when the television set stands by, which assures failure-free operation of the IIC bus and the television set and increases reliability of complete appliance. The isolating circuit can be used for television sets of the IIC buses.

Description

Buffer circuit on the television set iic bus

Technical field

The utility model belongs to the TV set circuit technical field, more particularly relates to the design of the buffer circuit on the television set iic bus.

Background technology

The iic bus of television set is the two-way serial data bus of a kind of two-wire, has the multiterminal control ability.Its one on two lines are serial data line SDA, and another is serial time clock line SCL.The various IC and other device that hang on the iic bus all carry out message transmission by SDA and SCL.

A lot of devices are all controlled by iic bus in the Core of TV set.According to the standard of iic bus, each device is in non-response status, and its SDA and SCL pin should be in high-impedance state.In actual applications, some components and parts occur after the standby power down through regular meeting, pin is not in high-impedance state, but has dragged down the level of bus.So just upset the normal read-write of other components and parts on bus.Make the television set cisco unity malfunction.

Summary of the invention

The purpose of this utility model, just be to overcome above-mentioned shortcoming and defect, provide a kind of in the television set standby, the components and parts of power down and not power down are isolated mutually, thereby guaranteed the normal operation of iic bus and the operate as normal of television set, improved the buffer circuit on the television set iic bus of its reliability.

In order to achieve the above object, this buffer circuit is connected on the iic bus of television set, is made of the gating switch between the IC of power down and not power down on iic bus components and parts.Gating switch adopts two metal-oxide-semiconductor field effect transistors to constitute.3 pin of two metal-oxide-semiconductor field effect transistors respectively with iic bus on D-SDA end and D-SCL hold and be connected, 1 pin of two metal-oxide-semiconductor field effect transistors respectively with iic bus on SDA end and SCL hold and be connected, 2 pin of two metal-oxide-semiconductor field effect transistors then are connected with the control power circuit 5VS of singlechip CPU.Adopted two MOS FET RK7002T116 as gating switch in the circuit.During standby, CPU control power circuit makes this road voltage of 5VS not work, 2 pin low levels of metal-oxide-semiconductor, and metal-oxide-

semiconductor

1,3 pin is obstructed, has turn-offed the bus that 1 pin links to each other, and has isolated the IIC device that 1 pin links to each other.During start, CPU control power circuit powers on 5VS, 2 pin high level of metal-oxide-semiconductor, and metal-oxide-

semiconductor

1,3 pin conducting, bus that links to each other with 1 pin and extension devices such as IC thereon just can operate as normal.

Two metal-oxide-semiconductor field effect transistors are the RK7002T116 type, its dependable performance, stable.

It is a kind of in the television set standby that the utility model provides, the components and parts of power down and not power down are isolated mutually, thereby guaranteed the normal operation of iic bus and the operate as normal of television set, improved the buffer circuit on the television set iic bus of its reliability.It can be widely used in the iic bus television set.

Description of drawings

Fig. 1 is a functional-block diagram of the present utility model.

Fig. 2 is its circuit theory diagrams.

Fig. 3 is the circuit diagram of embodiment 1.

Embodiment

Embodiment 1.Buffer circuit on a kind of television set iic bus is as Fig. 1～shown in Figure 3.It is connected on the iic bus of television set, is made of the gating switch (3) between the IC of power down and not power down on iic bus components and parts.Gating switch (3) adopts two metal-oxide-semiconductor field effect transistors (1) and (2) to constitute.3 pin of two metal-oxide-semiconductor field effect transistors (1) and (2) respectively with iic bus on D-SDA end and D-SCL hold and be connected, 1 pin of two metal-oxide-semiconductor field effect transistors (1) and (2) respectively with iic bus on SDA end and SCL hold and be connected, 2 pin of two metal-oxide-semiconductor field effect transistors (1) and (2) then are connected with the control power circuit 5VS of single-chip microcomputer (4).Device IC1～IC4 hangs on the iic bus among Fig. 1.

Two metal-oxide-semiconductor field effect transistors (1) and (2) are the RK7002T116 type.

Consult Fig. 3, this is the part of television set decoding deck circuit.The gating switch of this circuit (3) is isolated the components and parts of power down and not power down on the iic bus mutually.The IC device that iic bus is inserted in gating switch (3) back has TVP5147 (5), 24C00 (6), TDA9332 (7), AD9883 (8) and PLI2300 (9) etc.Gating switch (3) is connected with the control power circuit 5VS of single-chip microcomputer (4).

Embodiment 1 makes on the iic bus components and parts of power down and not power down isolate mutually in the television set standby, thereby has guaranteed the normal operation of iic bus and television set, has improved the reliability of complete machine.It can be widely used in the iic bus television set.

Claims

1. the buffer circuit on the television set iic bus, it is connected on the iic bus of television set, it is characterized in that it is made of the gating switch between the IC of power down and not power down on iic bus components and parts, gating switch adopts two metal-oxide-semiconductor field effect transistors, 3 pin of two metal-oxide-semiconductor field effect transistors respectively with iic bus on D-SDA end and D-SCL hold and be connected, 1 pin of two metal-oxide-semiconductor field effect transistors respectively with iic bus on SDA end and SCL hold and be connected, 2 pin of two metal-oxide-semiconductor field effect transistors then are connected with the control power circuit 5VS of single-chip microcomputer.

2. according to the buffer circuit on the described television set iic bus of claim 1, it is characterized in that said two metal-oxide-semiconductor field effect transistors are the RK7002T116 type.