Insulation protective circuit for DDC (Direct Digital Control) interface

Abstract

The invention relates to a video signal interface circuit and particularly discloses an insulation protective circuit for a DDC (Direct Digital Control) interface. A bidirectional insulator is connected onto each signal line between a DDC interface on a video signal input interface and an I2C (Inter-Integrated Circuit) interface of an E-EDID (Enhanced Extended Display Identification Data) information memory stack of video signal receiving equipment, each bidirectional insulator is connected with a pull-up resistor, and the E-EDID information memory stack of the video signal receiving equipment is connected with a pull-up resistor; and a bidirectional insulator is connected onto each signal line between the I2C interface of the E-EDID information memory stack of the video signal receiving equipment and an I2C interface of a local control core of the video signal receiving equipment, and the local control core of the video signal receiving equipment is connected with a pull-down resistor and a field effect tube. In the invention, a protective circuit is additionally arranged, thereby ensuring that no conflicts can be generated among the circuits of various parts in the aspects of electrical property and data reading/writing operation, preventing the data loss, and facilitating the maintenance process.

Description

technical field [0001] The invention relates to a video signal interface circuit, in particular to a DDC interface isolation protection circuit. Background technique [0002] The DDC interface is a sub-interface that must be included in today's mainstream video interfaces, such as DVI, VGA and other interfaces. That is to say, the aforementioned video interface, in addition to a main channel for transmitting video signals, also needs to include a sub-channel for transmitting DDC signals, and they are encapsulated in the same cable and the same plug. Through the DDC interface, the signal source, such as a graphics card, can perform two-way data interaction with the signal receiving device, such as a display. Through this interaction, the signal source can learn the detailed configuration information of the receiving device, so as to output video suitable for the display requirements of the receiving device. Signal. [0003] For existing video signal receiving equipment, the...

AI Technical Summary

Problems solved by technology

[0004] It can be seen that the widely used DDC implementation based on simple connection has many problems: because the DDC interface is simply connected to a storage body, the E-EDID information can only be written by an external device when the video receiving device leaves the factory. input, the receiving device cannot update its content by itself and cannot be upgraded

24C02, a serial non-volatile erasable storage body based on E2 technology, is easy to lose data under external interference. Based on the above reasons, the receiving device cannot restore the E-EDID information. Once lost, it can only be returned to the factory for repair. repair cost is too high

The video interface cable is directly connected to the storage body, external interference, and the signal pressure difference of the video originating from the video receiving device may have an impact on the storage body, resulting in data loss

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