CIRCUIT BOARD INSERTION CIRCUITRY FOR HIGH RELIABILITY BACKPLANES

摘要

Circuit board insertion circuitry is used in conjunction with a staggered electrical connector (not shown). The insertion circuitry includes an isolated circuit (B1 and M2) which receives a high system voltage upon first stage contact between the card (100) and a high voltage bus (40), and uses that high system voltage to tristate the output of a transceiver (10) on the circuit board (100) prior to second stage contact being made between the transceiver (10) and the backplane data bus (20). Override circuitry (15) for overriding the tristating effects of the isolating circuit is provided such that when the bias circuit (15) which controls the transceiver output is properly powered, the bias circuit will control the transceiver output, and not the isolated circuit. Power fault isolation is also provided by a relatively large resistor (R1) and a Schottky diode (D1).