The Speaker Company TTP 248M service manual TTP-248M Bar Code Printer Power Down Sensor, Vcc

TTP-248M Bar Code Printer

Service Manual

3.8 Power Down Sensor

1. 9V VCCL

VCC

R118	1		U21
1	R116	8	VDD	SW	1		L1 8		L2 1
		7			2
			Ip k	SWE
R117	1	6			3		33 0u		0
			VCC	TC
		5			4		D10
			Vref	GND
C21						C72	SS14
			34 06 3		C8
10 uF			R96		10 0p	15 00 pF	C16	C66	C69
							0. 1u	47 0u	10 0u /35 V
	R122		1. 9K
	3. 6K								C76
									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
	4. 42k

AGND
Analo g Gro un d
VMM		JP30
	2
	1
		2PIN

			GND
		U20
		SI-80 33 JD			L1 7
	1			2
		Vin	SW
					10 0u
	ff		Vos	4
C22	o/O		ND
	N		G	C71	D9
22 0u F
					SS24
		5	3	15 00 pF
			C7
		0. 47u F
			GND

			3. 3V
	L2	0	VCC	JP29
				2
	0			1
				2PIN
				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
	SI-80 50 JD				L1 6
1				2
	Vin		SW
					10 0u
ff			Vos	4
		G ND
N o/O

C63			C70	D8
22 0u /35 V	5	3		SS24
			15 00 pF
		C6
	0. 47u F 10V

L2 2
0
L1 1	GND
0
L3 7
0

		5V
	L1 9	VDD		JP31
				2
	0			1
				2PIN
		C67	C74
C14	C64	10 0u /35 V	10 0u F	GND
0. 1u	47 0u

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)

27