Service manual

4. BOARD/UNIT DESCRIPTION
Service Manual BSM-4100 4.5
d) Power control block
The power control block consists of the power supply microchip controller, DC/DC
converters, buzzer and its driver and battery interface.
+15 V from the power supply unit or +12 V from the rechargeable battery is
converted to +3.3 V, +5 V and +24 V supply voltages by the DC to DC converters
and power supply microchip controller.
When the line voltage is supplied to the instrument and the battery is inserted into
the instrument, the power supply microchip controller charges the battery with
approx. 190 mA (normal charge) for 15 hours. After the 15 hours, the controller
uses trickle charging to charges the battery with approx. 60 mA so that the fully
charged battery condition is maintained.
If the normal or trickle charging is interrupted for one hour or less by power failure
or disconnection of the power cord and the battery is not removed from the
instrument, the controller memorizes how many hours the battery is charged before
the interruption. After it is removed, the controller charges the battery under the
memorized condition to protect the battery against excessive charge.
System Control Block
Recorder Control Block
Host CPU
Local CPU
ROM
RAM
RACOON
I/O
Data flow in normal operation
Program data flow in upgrade
+15 V (AC operation)
or
+12 V (Battery operation)
Power
Control
Block
+3.3 V for CPUs
+5 V for Peripherals
+24 V for Recorder
to Battery
Power Switch