摘要：该电路提供了一个4-20mA电流环路灵活的故障保护。此外，它包括为恢复环路上施加的数字信号（如HART协议）的电路。Maxim/Dallas > App Notes > CIRCUIT PROTECTION INTERFACE CIRCUITS Keywords: 4-20mA current loop, fault protection, current limiting, current-sense amplifiers Apr 22, 2004 APPLICATION NOTE 3195 Add Fault Protection to 4-20mA Loop Supply This circuit provides flexible fault protection for a 4-20mA current loop. In addition, it includes circuitry for recovering digital signals (such as the HART protocol) imposed on the loop. 4-20mA current loops consist of a power source and current-measuring device at the control end, and a field transmitter that senses process-variable information (like temperature or pressure) and converts it to a current (Figure 1). Most 4-20mA industrial loops are powered by 24VDC, but that voltage can range from 12V to 36V. The loop voltage in o……