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TTP-248M Bar Code Printer
Service Manual
3.8 Power Down Sensor
GND
Analo g Ground
C63
220u/35V
D8
SS24
L16
100u
C64
470u
C67
100u/35V
L19
0
VDD
AGND MGND
MOTOR_GND
L22
0
VMM
C14
0.1u
C70
1500pF
C73
2200u/35V
GND
C6
0.47uF 10V
D9
SS24
L17
100u
C65
470u
C68
100u/35V
L20
0
VCC
C15
0.1u
C71
1500pF
SW
1
SWE
2
TC
3
GND
4
Vref
5
VCC
6
Ip k
7
VDD
8
U21
34063
R1161
R117 1
R96
1.9K
R122
3.6K
GND
C8
100p
D10
SS14
L18
330u
C66
470u
C69
100u/35V
L21
0
VCCL
R118
1
C16
0.1u
C72
1500pF
5V
3.3V
1.9V
12
13
14
U5D
LM324
VCC
R4
30.9k
R5
4.42k
R6
10M
AGND
Analo g Ground
P_INT
R7
4.42K
R8
3.6K
GND
1.5V
C74
100uF
C75
100uF
C76
100uF
C21
10uF
C22
220uF
Vin
1
SW
2
GND
3
Vos
4
No/Off
5
U19
SI-8050JD
Vin
1
SW
2
GND
3
Vos
4
No/Off
5
U20
SI-8033JD
C7
0.47uF
1
2
JP29
2PIN
1
2
JP31
2PIN
1
2
JP30
2PIN
AGND
GND
GND
1
2
3
4
5
6
7
8
9
10
11
J2
11_PIN
L11
0
L37
0
Fig. 3.6 Power Down Sensor Circuit
PIN U19 ----SJ8050JD is used to provide 5V to CTHP, LCD, motor, connector.
PIN U20 ---- SJ8033JD is used to provide 3.3V to CPLD, memory.
PIN U21 ---- 34063 is used to provide 1.9V to CPU。
∣Vout∣=1.25(1+R96/R122)