__________________________________________________________________________________________
4-12 BATTERY CIRCUIT
When the +18V supply starts dropping, as in a power fail condition, the voltage through the divider
network drops accordingly.
When +18V no voltage, Q3 and D8 are shut off current VBB is through the D9 from battery.
When the voltage at +18V has dropped, voltage back-up is provided by the battery.
The battery voltage VBB goes to the CPU and external RAM
.
Battery specification
Type
: SUM-3×3pcs
Voltage
: 1.5V x 3 = 4.5V
1
2
CN2
B2B-XH-A
BACK UP(1.5Vx3pcs)
C9
0.1uF
+
EC3
10uF_16V
B
E
C
Q2
2SC3242
A
K
ZD1
HZ6C3TA-E
A
K
D8
1N4148
A
K
D7
1N4148
+
EC4
10uF_16V
+
EC5
10uF_16V
_____________________________________________________________________________
VBB
A
K
D9
1N4148
A
K
D20
JUMPER
R22
3.3K
A
K
ZD2
HZ5B1
R23
330
B
E
C
Q3
2SC1815
R26
100
R27
4.7K
C2
0.01uF
PF
VCC
Y110910 – 8
ECR7100 Service Manual
55
