
TTP-248M Bar Code Printer
Service Manual
3.8 Power Down Sensor
1. 9V VCCL
VCC
R118 | 1 |
| U21 |
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1 | R116 | 8 | VDD | SW | 1 |
| L1 8 |
| L2 1 |
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| 7 | 2 |
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| Ip k | SWE |
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R117 | 1 | 6 | 3 |
| 33 0u |
| 0 | ||
VCC | TC |
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| 5 | 4 |
| D10 |
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| Vref | GND |
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C21 |
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| C72 | SS14 |
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| 34 06 3 |
| C8 |
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10 uF |
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| R96 |
| 10 0p | 15 00 pF | C16 | C66 | C69 |
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| 0. 1u | 47 0u | 10 0u /35 V | |
| R122 |
| 1. 9K |
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| 3. 6K |
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| C76 |
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| 10 0u F |
P_ INT
J2
1
2
R7
4. 42K
U5D
131. 5V
14
12R8
3.6K
LM32 4
| R4 |
R6 | 30 .9k |
GND | |
10 M | R5 |
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| 4. 42k |
AGND |
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Analo g Gro un d |
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VMM |
| JP30 | ||
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| 2 |
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| 1 |
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| 2PIN |
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| GND |
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| U20 |
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| L1 7 | ||
| 1 |
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| 2 | |
| Vin | SW |
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| 10 0u | ||
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| ff |
| Vos | 4 |
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C22 | o/O |
| ND |
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| N |
| G | C71 | D9 |
22 0u F |
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| SS24 |
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| 5 | 3 | 15 00 pF |
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| C7 |
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| 0. 47u F |
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| GND |
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| 3. 3V |
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| L2 | 0 | VCC | JP29 |
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| 2 | ||
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| 0 |
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| 1 |
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| 2PIN |
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| GND |
C15 | C65 |
| C68 | C75 |
0. 1u | 47 0u |
| 10 0u /35 V | 10 0u F |
3
4
5
6
7
8
9
10
11
11 _PIN
AGND |
C73
22 00 u/3 5V
AGND | MGND |
Analo g Gro un d | MOTOR_GND |
| U19 |
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| L1 6 | ||
1 |
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| 2 | |
Vin |
| SW |
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| 10 0u | ||
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ff |
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| Vos | 4 |
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| G ND |
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N o/O |
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C63 |
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| C70 | D8 |
22 0u /35 V | 5 | 3 |
| SS24 |
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| 15 00 pF |
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| C6 |
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| 0. 47u F 10V |
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L2 2 |
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0 |
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L1 1 | GND |
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0 |
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L3 7 |
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0 |
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| 5V |
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| L1 9 | VDD |
| JP31 |
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| 2 | |
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| 0 |
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| 1 |
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| 2PIN |
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| C67 | C74 |
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C14 | C64 | 10 0u /35 V | 10 0u F | GND |
0. 1u | 47 0u |
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Fig. 3.6 Power Down Sensor Circuit
PIN U19
PIN U20
PIN U21
∣Vout∣=1.25(1+R96/R122)
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