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LTM2881 Failsafe operation timing

Category: Hardware
Product Number: LTM2881

We have found that depending on the message content, it takes varying amount of time for the failsafe function to drive the receiver output high.   Adding a biasing network has very little impact.   This is a 2 transceiver 485 network with one passive receiver (always enabled).   A message is sent from our test 485 transceiver and after the message ends, the transmitter is disabled.   This leaves 3 receivers on an inactive bus.   We see the LT2881 take on the order of 200usec to go to a failsafe condition (Vdiff <200mV).