RS485 driver of low bit error rate, low working power supply voltage and high ESD

A low power supply voltage, RS485 technology, applied in the field of integrated circuits, can solve the problems of unstable charge and discharge current, high bit error rate of transmitted data, low working power supply voltage, etc., and achieve low bit error rate, high ESD performance, and low power supply The effect of voltage

Active Publication Date: 2017-12-19
CHENGDU SINO MICROELECTRONICS TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The operating power supply voltage of the single-tube structure is low, and the requirement of a differential swing greater than 1.5V can be achieved at a low voltage, but the ESD performance is poor
[0005] For RS485 transmitters on the market, the pre-driver usually uses a switch circuit, the charging and discharging current is unstable, and the noise is large, resulting in a high bit error rate and a short transmission distance for RS485 transmission data.

Method used

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  • RS485 driver of low bit error rate, low working power supply voltage and high ESD
  • RS485 driver of low bit error rate, low working power supply voltage and high ESD
  • RS485 driver of low bit error rate, low working power supply voltage and high ESD

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Embodiment Construction

[0024] Such as figure 1 , in the existing RS485 transmitter, the power tube output is a stacked MOS structure. Usually the voltage drop of a MOS is 0.35V. In order to ensure the output of 1.5V differential output voltage, the minimum power supply voltage is 0.35V*4+1.5V=2.9V, which can meet the requirements of low power supply voltage (such as 3.0V). Although the stacked MOS structure can meet the requirements of low power supply voltage operation, it needs to occupy a large area of ​​the chip and increase the cost of the chip.

[0025] refer to figure 2 In the 3RS485 transmitter shown in the figure, the power tube output is a diode stacked MOS structure. Usually, the voltage drop of a MOS is 0.35V, and the voltage drop of a diode is 0.65V. In order to ensure a 1.5V differential output voltage, the minimum power supply voltage is 2 *(0.65+0.35)V+1.5V=3.5V, which cannot meet the requirements of low power supply voltage operation.

[0026] refer to Figure 4 The RS485 trans...

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PUM

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Abstract

The invention discloses an RS485 driver of a low bit error rate, a low working power supply voltage and high ESD, and relates to integrated-circuit technology. The driver includes two power tube circuits. Each power tube circuit includes a front-stage driving unit, a power tube unit and a feedback detection unit. The driver is characterized in that power tube substrates in the power tube unit are floating, and the front-stage driving unit adopts constant-current source front-stage driving. The driver has the advantages that the working power supply voltage is low, costs are low, the bit error rate is low, ESD performance is high, the bit error rate of RS485 transmission can be effectively decreased, and ESD capability of power tubes can be improved.

Description

technical field [0001] The present invention relates to integrated circuit technology. Background technique [0002] At present, in long-distance communication, RS485 has become the first choice for people, because the RS485 bus has the advantages of simple structure, easy control, and easy price. The structure of the RS485 transmitter on the market is usually a dual-tube structure, the working voltage is at least 5V, and the bit error rate is relatively high. [0003] The ESD performance of the double-tube stack structure is relatively high, but the working voltage usually needs to be above 5V, and the chip area is relatively large to ensure that the output swing of the transmitter is greater than the requirement of 1.5V. [0004] The operating power supply voltage of the single-tube structure is relatively low, and the requirement of a differential swing greater than 1.5V can be achieved at a relatively low voltage, but the ESD performance is poor. [0005] For RS485 tra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F13/40G06F13/42
CPCG06F13/4072G06F13/4282G06F2213/0002
Inventor 曹小强黄俊杰廖志凯
Owner CHENGDU SINO MICROELECTRONICS TECH CO LTD
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