Rfx-Rmr - Power Supplies And Monitoring - RF Central RFX-RMR Operator's Manual

8.7

RFX-RMR - Power supplies and monitoring

The RFX-RMR power supply is mounted on the under-side of the Mother Board. See photograph in
section 8.6
The +12v input supply is filtered and regulated by IC7, +5v linear regulator. This provides the +5 volt
supply to the Receiver board circuits and is also the reference voltage for the discrete 'low drop out'
10.5-volt regulator circuit comprising TR3, TR6, TR7, and associated components.
The +10.5v supply provides the board circuits and the DC /DC converter IC16. The converter provides
the –4.3v supplies for the board.
The +5v supply is current limited by the inclusion of R56, R57 in the supply to IC7. The +10.5v supply
is current limited by TR4 and sense resistors R46, R47. Supply over voltage protection is controlled by
TR5. The +10.5v regulator circuit is turned off if the input supply exceeds ~15.5v.
The input supply monitor circuit (IC12) and '12v OK' bi – color LED are designed to indicate supply OK
between 10.5 and 15.5v. Over this range the LED will be illuminated green. Above and below these
limits the LED will illuminate red.
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RFX-RMR Issue 1.0 page 25 of