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Receiving circuit of RS-485 receiver

A technology of RS-485 and receiving circuit, which is applied in the field of receiving circuit of high-sensitivity RS-485 receiver, can solve the problems of affecting communication reliability and low anti-interference ability, and achieve the suppression of common mode noise and high frequency differential mode noise , Improve the effect of receiving sensitivity

Inactive Publication Date: 2013-12-04
HANGZHOU VANGO TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a receiving circuit of an RS-485 receiver, which is used to solve the problem that the receiving circuit of the RS-485 receiver in the prior art has low anti-interference ability and affects communication reliability

Method used

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  • Receiving circuit of RS-485 receiver
  • Receiving circuit of RS-485 receiver
  • Receiving circuit of RS-485 receiver

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Embodiment Construction

[0019] see image 3 As shown, the receiving circuit of the RS-485 receiver implementing the present invention includes first and second fully differential amplifiers, bidirectional hysteresis comparators and output controllers connected in series.

[0020] The first-stage fully differential amplifier is a rail-to-rail (R2R) fully differential amplifier, and the second-stage fully differential amplifier is a P-tube input fully differential amplifier.

[0021] In specific implementation, the input terminals A and B of the RS-485 receiver pass through the first and second resistors R respectively 1a , R 1b It is connected to the non-inverting input terminal and the inverting input terminal of the first-stage fully differential amplifier, and a third resistor R is connected between the negative output terminal and the non-inverting input terminal of the first-stage fully differential amplifier 2a , and a fourth resistor R is connected between its positive output terminal and inv...

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PUM

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Abstract

A receiving circuit of an RS 485 receiver is provided. The receiving circuit includes a first stage fully-differential amplifier, a second stage fully-differential amplifier, a bi-directional hysteresis comparator and an output controller which are connected in series with one another, wherein the first stage fully-differential amplifier adjusts common-mode electrical level, the second stage fully-differential amplifier amplifies differential-mode electrical level, and the output controller controls output through enabling. When receiving is enabled, the receiver performs output normally, and when receiving is disabled, the receiver outputs high electrical level, and therefore, common-mode noise and high-frequency differential-mode noise can be greatly suppressed, and receiving sensitivity can be improved.

Description

【Technical field】 [0001] The invention belongs to the field of electrical devices and relates to a new receiving circuit of a high-sensitivity RS-485 receiver. 【Background technique】 [0002] As a commonly used interface device, RS-485 chip has been widely used in many fields such as industrial control, instrument, meter, multimedia network, and mechatronics products. Such as figure 1 As shown, the RS-485 communication interface chip mainly includes two working modes: balanced transmission and differential reception. In the transmission mode (DE enabled), the transmitter converts TTL level or CMOS level DI into a differential signal (A-B) for output; In receive mode ( / RE enabled), the receiver converts the differential signal (A-B) into a TTL level or a CMOS level (RO), which eliminates ground offsets and induced noise that appear as common-mode voltages in the bus The influence of the signal has a strong ability to suppress common-mode interference. [0003] figure 1 Am...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/02
Inventor 林玲
Owner HANGZHOU VANGO TECH
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