查阅东沃电子“ESD-SM712 Datasheet”产品手册可知：

1）ESD静电防护器件SM712特性

√ Low capacitance

√ Solid-state silicon avalanche technology

√ IEC 61000-4-4 (EFT) 40A (5/50ns)

√ 峰值脉冲功率Peak Pulse Power ( tp =8/20μs): 400W

√ 工作电压Reverse Stand-Off Voltage: 12V和7V

√ 钳位电压Clamping Voltage: 26V

√ 结电容Junction Capacitance: 45pF 75pF

3）ESD静电防护器件SM712应用

EIA RS-485 specifies a ±7V ground difference between devices on the bus. This permits the bus voltage to range from +12V (5V + 7V) to -7V (0 - 7V). The SM712 is designed to protect two RS-485 data lines in extended common mode applications. The SM712 may be used to protect devices from transient voltages resulting from ESD, EFT, and lightning. The device is designed with asymmetrical operating voltages for optimum protection. The TVS diodes at pins 1 and 2 have a working voltage of 12 volts. These pins are connected to the differential data line pairs. The TVS diodes at pin 3 have a working voltage of 7 volts. Pin 3 is connected to ground. The internal TVS diodes of the SM712 will protect the transceiver input from positive transient voltage spikes greater than 12V and Negative spikes greater than 7V. A series current limiting resistor may be added in applications requiring enhanced surge immunity.

由此可知，SM712是RS-485接口常用的静电ESD防护器件，也是客户常咨询的ESD二极管。关于SM712的价格、现货、交期等其他方面的问题，可以咨询东沃电子销售工程师！

       原文标题 : SM712 RS-485端口专用ESD静电保护二极管