TC7129 View Datasheet(PDF) - TelCom Semiconductor Inc => Microchip

Part Name

Description

Manufacturer

TC7129

4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH ON-CHIP LCD DRIVERS

TelCom Semiconductor Inc => Microchip 

4-1/2 DIGIT ANALOG-TO-DIGITAL

CONVERTER WITH ON-CHIP LCD DRIVERS

1

TC7129

V+

V+

2

24

EXTERNAL

LOGIC

ILOGIC

TC7129

36

DGND

23

V–

Figure 5. External Logic Referenced Directly to DGND

24

EXTERNAL

LOGIC

TC7129

3

36 DGND

ILOGIC

23

V–

Figure 6. External Logic Referenced to DGND With Buffer

4

Temperature Compensation

For most applications, VDISP (pin 19) can be connected

directly to DGND (pin 36). For applications with a wide

temperature range, some LCDs require that the drive levels

vary with temperature to maintain good viewing angle and

display contrast. Figure 7 shows two circuits that can be

adjusted to give temperature compensation of about 10

mV/°C between V+ (pin 24) and VDISP. The diode between

DGND and VDISP should have a low turn-ON voltage be-

cause VDISP cannot exceed 0.3V below DGND.

5

V+

V+

1N4148

5 kΩ

75 kΩ

39 kΩ

24

200 kΩ

–

TC7129

19

+

VDISP

36

DGND

23

39 kΩ

24

20 kΩ

2N2222

TC7129

19

VDISP

18 kΩ

36

DGND

23

V–

V–

Figure 7. Temperature Compensating Circuits

TELCOM SEMICONDUCTOR, INC.

6

7

8

3-239

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