Digital quantity input circuit and equipment

Abstract

The invention provides a digital quantity input circuit and equipment. The digital quantity input circuit comprises a first port and a second port which are taken as input ports; an anti-reverse voltage division module which is connected between the first port and the second port, wherein the anti-reverse voltage division module comprises a first voltage division circuit and a second voltage division circuit which are connected in parallel; a rectifying module which is provided with a first pin and a third pin which are used as inputs of the rectifying module, and a second pin and a fourth pinwhich are used as outputs of the rectifying module, wherein a first pin of the rectifying module is connected with the output ends of the first voltage division circuit and the second voltage division circuit, and a third pin of the rectifying module is connected with the second port; and an isolation output module, wherein the two input ends of the isolation output module are connected between the second pin and the fourth pin of the rectifying module, and the isolation output module performs isolation processing on the electric signal output by the rectifying module and outputs the electricsignal through the two output ends of the isolation output module. According to the invention, a low-cost device is adopted for design, so that the device is compatible with various signal sources and has a protection function at the same time.

Description

technical field [0001] The invention relates to the technical field of digital quantity input and output, in particular to a digital quantity input circuit and equipment. Background technique [0002] At present, in the field of electronic circuit technology, commonly used digital input circuits usually only support PNP-type input wiring or NPN-type input wiring, and the wiring method is single. If two wiring methods need to be compatible, the design cost will increase. [0003] Such as figure 1 The digital input circuit shown is designed with two comparators and multiple resistors. The circuit uses a 24V power supply voltage Vcc, and a 3.3V pull-up voltage VL is added to the output terminal OUTPUT. The working principle of this circuit is: when the input terminal INPUT is floating and there is no level signal input, the voltage VIN=Vcc*R4 / (R4+R5 ), at this time the output terminal OUTPUT outputs a high level, and the logic value is "1"; when the input terminal INPUT has a...

AI Technical Summary

Problems solved by technology

Although this circuit is compatible with the input wiring of NPN sensors and PNP sensors, the circuit requires 4 MOS transistors and 2 photocouplers, which is costly and does not have protective functions. Adding EMC devices separately will further increase the design cost.

Images