TRANSCEIVER 400 MHz MTP700 Portable Radio / Detailed Service Manual 4.1 - 23
VREF2 Linear Regulator
VREF2 is a programmable linear regulator. It is programmed using RedCap2 SPIB bus
from 0.95V to 2.775V. For this radio, it is programmed to 2.775V which supplies directly
(VREF2_2.775_DIG) the backlights and filtered (VREF2_2.775V) the SSC section
(Tx/Rx-LED).
TS_REF Linear Regulator
TS_REF is a fixed output linear regulator. It is supplied internally from the V2 linear regu-
lator. It is set to 2.3V. The radio uses TS_REF for the AD voltage dividers. It is not active
at POR.
5.5V Linear Regulator
This is an external linear regulator fed by SWB+. It is used to supply GCAP3 DSC regula-
tor and the Battery Interface Circuitry.
DSC Linear Regulator
DSC is a fixed output linear regulator. This regulator is active during POR in the 5V mode.
DSC is supplied from an external 5.5V linear regulator. The output voltage is filtered
(5V_RF) to supply the WPIC+, 2nd LO PLL-IC and ESCORT-IC charge pump circuits, the
PA bias OP and LNODCT_RFOUT circuit.
Current Limit
The SWB+ current limit regulator provides power from the phone battery to clip-on acces-
sories. It is enabled only when the phone is powered up and an accessory which requires
power from the phone is connected.
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