GE BRIVO MR355, Service Training, Page: 151 / 227

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4. Driver Module Interface has the following functions:
a) Multi Coil TR Bias
The Mega Switch receives Multicoil TR bias (MCB) from the Driver Module Lite and these signals are
routed to each coil port.
The MC TR bias is specified as following:
MC TR bias input (Transmit Mode) supplied by Driver Module MC Driver board +3, +5 or +7V +/- 0.1V @
500mA
Maximum MC TR bias input (Receive Mode) supplied by Driver Module MC Driver board -5 V +/- 0.1V @
500mA
b) Control Signal of RF Routing
The Mega Switch receives a 16 bit serial stream of data to control RF routing from the Driver Control
Board within the Driver Module on differential lines (DATA, STROBE, OE), converts these lines to digital
signals (data, strobe, enbale), and converts this serial data to parallel signals.
c) Power Supply From Driver Module
The Mega Switch re15V and
– 15V powers from the Driver Module Lite. These supply voltages
are used for each coil port, Body Preamp Bias Power. +10V power which is used for each coil port is
generated by linear regulators from +15V. Note that +10V is not supplied to the Legacy port, only +/-
15V are supplied.
d) Body Preamp Bias and Over Current Detect
The Body preamp inputs are biased with 15Vdc supply from the Driver Module through a inductor at
all times (Bias-T). This bias circuitry has PTC resettable fuse and detects over-current state, and
allows bias output current to 300 mA flows to the preamps at maximum. The intent of this method is
to protect the circuit traces and coaxial cables in the event of a shorted preamp or cable. A voltage
comparator circuit is provided to determine when such a fault condition has taken place. The
comparator ’ s output will remain Low so long as the bias circuit in over-current detected state. While
the comparator output is Low, yellow LED will remain illuminated.