Panasonic TDA 100 Service Manual page 30

KX-TDA100CE
in IC413, C453 and C454.
+3.3V generated in DC/DC converter is converted to 1.8V in the back board or IC403 and Q405 via Q404 and supplied to
IC101 core power, and also is converted to 1.9V in IC404 via the back-flow prevention diode D407 and supplied to IC101
clock block power.
BAT401, which is a lithium battery for memory backup, is connected to the power supply of IC301, IC302 (SRAM) via D408,
D409.
IC411 compares BAT401 output voltage to the reference voltage (about 2.8V) and drives LED (BATALM) that indicates
dropping of backup voltage.
IP401and IP402 block the line respectively when over current flows to +15V and +3.3V line.
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