Casio SF-8500 Service Manual & Parts List page 19

7) Power supply chip SC371015FU
C3
+
20 17
POWER SUPPLY CHIP
SC371015FU
PDB
GND1
31 32
FROM
GATE ARRAY
Back-up battery
VOT terminal
The V comp0 ~ V comp2 and Sub out outputs are the battery voltage detection outputs. According to
VDD1 and VDD2 voltages, those outputs will change the status as follows:
OUTPUTS
V COMP 0
V COMP 1
V COMP 2
SUB OUT
8
VSS
9
V1
10
V2
11
V3
12
V4
7
V COMP2
6
V COMP1
5
V COMP0
4
SUB OUT
2
VO1
VDD
(4.3 V ~ 4.7 V)
1
VDD1
19
VDD2
3
SUB IN
GND2
22
MAIN POWER
CR2032
SUPPLY CIRCUIT
STATUS "H"
When the VDD1,2 voltages When the VDD1,2 voltages Switch off the LCD
are more than 3.7±0.1V.
When the VDD1,2 voltages When the VDD1,2 voltages Main battery check
are more than 4.38±0.155V. are less than 4.38±0.155V.
When the VDD1,2 voltages When the VDD1,2 voltages Main battery check
are more than 4.58±0.165V. are less than 4.58±0.165V.
When the SUB IN voltage
is more than 2.5±0.065V.
— 18 —
The IC SC371015FU is power supply chip for
SF-8500. When IC SC371015FU receives a Volt-
age 5V from main power supply circuit at the ter-
minal VDD1(Pin No.2), the regulated voltage
VDD (4.3~4.7V) will be applied to the VDD lines.
The outputs VSS (VREG) and V1~V4 are the
LCD drive voltages. When the terminal PDB be-
comes "H", those voltages are generated by IC
SC371015FU and capacitors C3 and applied to
LCD driver IC MSM6385AV-Z-358B.
The voltages for LCD driving are shown below:
LCD DRIVE VOLTAGE
Contrust : Min.
VSS(VREG) -3.07
V1 +3.50
V2 +2.57
V3 -1.16
V4 -2.11
STATUS "L"
are less than 3.7±0.1V.
When the SUB IN voltage
is less than 2.5±0.065V.
Value (Approx.) [V]
Contrust : Max.
-5.27
+3.23
+2.02
-2.80
-4.04
NOTE
driving voltages
Back-up battery check