Circuit for improving optocoupler response speed based on image current source

Abstract

The present invention discloses a circuit for improving an optocoupler response speed based on an image current source. The circuit comprises an optocoupler triode, an input end circuit and an output end circuit which are connected with the optocoupler triode and an image current source taken as a load and formed by two image connection triodes, wherein the image current source is connected with the output end of the optocoupler triode, and the output end of the image current source outputs switch signals. The improved circuit obviously shortens the time-delay time of the optocoupler, reduces the current of the front and back ends of the optocoupler, overcomes the problems of the big discreteness of optocoupler CTR parameters and the optical attenuation, is high in transmission efficiency, good in universality and flexible in usage and is especially suitable for the data transmission in the intelligent ammeter industry.

Description

technical field [0001] The invention relates to an optocoupler response circuit, in particular to a circuit for improving the response speed of the optocoupler based on a mirror current source, and belongs to the field of electronic technology. Background technique [0002] Low-speed optocouplers are often used in low-speed serial data communication circuits, such as RS485 communication. RS485 communication stipulates that the bit width deviation of serial data bits should not exceed 30%. According to this, common low-speed optocouplers can only be used for serial communication with a baud rate of 4800 baud at most. It can only be used for serial communication at 9600 baud rate. RS485 serial communication at 9600 baud rate, the bit width is 104uS, and the 30% bit width deviation is about 32uS. [0003] The circuit connection diagram and corresponding working waveform diagram of the existing low-speed optocoupler are as follows: figure 1 As shown, the low-speed optocoupl...

AI Technical Summary

Problems solved by technology

However, the reduction of switching amplitude caused by optical attenuation cannot be guaranteed in the full temperature operating range and product life cycle, that is, the low level amplitude is too high

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