Are the AD5700/AD5700-1 Rx and Tx pins in hi-z (essentially benign) when the part is powered-off and/or held in reset?
When /RESET is low (active), the part is in power-down mode. In this mode, the receive, transmit, and oscillator circuits are all switched off.
The HART_OUT pin will hold at ~Vref/2 when in reset (so depends on the REF_EN pin and the voltage on Vref), while the RX pin won’t really change its input impedance from the ON mode. Aside from the internal ESD diodes to the supply and ground, the HART_IN pin goes straight to the internal filter.
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