All devices in the family contain a refresh circuit to guarantee dc correctness
at power up. If no pulses are received on the secondary side of the transformer
for approximately 200 µs, the input side is assumed to be unpowered or
nonfunctional and all outputs are set to a default state. The ADuM1440/41/42
output default is high, while the ADuM1445/46/47 output default is low.