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Hysteresis Comparator Applied to rs-485 Receiver

A technology of RS-485 and hysteresis comparator, which is applied in the field of electric energy grid communication, and can solve the problem that the hysteresis interval of the comparator becomes a positive interval, etc.

Active Publication Date: 2018-11-20
湖南芯力特电子科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In order to solve the above-mentioned technical problems, the object of the present invention is to provide a hysteresis comparator applied to the RS-485 receiving end to solve the problem that the comparator hysteresis interval becomes a positive interval after polarity exchange

Method used

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  • Hysteresis Comparator Applied to rs-485 Receiver
  • Hysteresis Comparator Applied to rs-485 Receiver
  • Hysteresis Comparator Applied to rs-485 Receiver

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Embodiment Construction

[0017] The present invention will be described in detail below with reference to the accompanying drawings and examples.

[0018] Refer to attached figure 1 As shown, a kind of hysteresis comparator applied to the RS-485 receiving end of the present invention includes a voltage divider circuit, a folded cascode operational amplifier, a polarity exchange switch and a hysteresis voltage control circuit:

[0019] The voltage dividing circuit includes: a first PMOS transistor MP6, a second PMOS transistor MP7, a third PMOS transistor MP4, a fourth PMOS transistor MP5, and four resistors: a first resistor r1, a second resistor r2, and a third resistor r3 , the fourth resistor r4, wherein, the source of the first PMOS transistor MP6 and the source of the second PMOS transistor MP7 are both connected to the power supply voltage VDD, the gate is connected to the first bias voltage VBP1, the first PMOS transistor MP6 The drain is connected to the source of the third PMOS transistor M...

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Abstract

The invention discloses a hysteresis comparator applied to an RS-485 receiving end. The hysteresis comparator comprises a voltage dividing circuit, a folded cascade operational amplifier, a polarity exchange switch and a hysteresis voltage control circuit, wherein the voltage dividing circuit is used for performing level linear displacement of two input signals of the hysteresis comparator, and facilitating subsequent circuit processing; the folded cascade operational amplifier is connected with the voltage dividing circuit, and is used for comparing the two signals after level linear displacement; the polarity exchange switch is arranged in the folded cascade operational amplifier, and exchanges polarities of the comparator correspondingly according to digital output results of an external polarity detection system; and the hysteresis voltage control circuit is connected with the folded cascade operational amplifier, and used for adjusting a hysteresis voltage interval. The hysteresis comparator solves the problem that a hysteresis interval is a positive interval after comparator polarity exchange in the nonpolarity RS-485 receiving end, and can ensure that the hysteresis interval of the comparator to be positioned between -200mV and -50mV before and after polarity exchange.

Description

technical field [0001] The invention relates to the field of electric power grid communication or the field of analog circuit technology, in particular to a hysteresis comparator applied to an RS-485 receiving end. Background technique [0002] RS-485 is a serial interface standard developed by the Electronics Industries Association (EIA) and the Telecommunications Industry Association (TIA). The RS-485 interface has the characteristics of high noise suppression, relatively high transmission rate, long transmission distance, and wide common mode range. At the same time, the RS-485 communication interface chip has the advantages of convenient control and low cost. [0003] The pin definition of the RS-485 communication interface chip is attached figure 2 As shown, among them: RO is the output signal of the receiving end; RE is the enabling signal of the receiving end; DE is the enabling signal of the sending end; DI is the input signal of the sending end; VDD is the power su...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03K5/22
CPCH03K5/22
Inventor 谢亮李彬张文杰金湘亮
Owner 湖南芯力特电子科技有限公司