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

CREF

RINT

CINT

2

REF HI

REF LO

IN HI

DE

INT1

DE–

DE

DE+

–

+ BUFFER

INTE-

GRATOR 10

–

pF

+

100 pF

X10

COMPARATOR 1

+

–

TO DIGITAL

SECTION

COMMON

IN LO

CONTINUITY

DE+

INT1, INT2

DE–

ZI, X10

INT

REST

–V+

200 mV

–

500 kΩ

+

CONTINUITY

COMPARATOR

TC7129

COMPARATOR 2

TO DISPLAY DRIVER

3

4

Figure 13. Integrator Block Diagram

Table I. Switch Legends

Label

DE

DE–

DE+

INT1

INT2

INT

REST

ZI

X10

X10

Meaning

Open during all deintegrate phases.

Closed during all deintegrate phases when input

voltage is negative.

Closed during all deintegrate phases when input

voltage is positive.

Closed during the first integrate phase

(measurement of the input voltage).

Closed during the second integrate phase

(measurement of the amplifier offset).

Open during both integrate phases.

Closed during the rest phase.

Closed during the zero-integrate phase.

Closed during the X10 phase.

Open during the X10 phase.

The buffer amplifier has a common-mode input voltage

range from 1.5V above V– to 1V below V+. The integrator

amplifier can swing to within 0.3V of the rails, although for

best linearity the swing is usually limited to within 1V. Both

amplifiers can supply up to 80 µA of output current, but

should be limited to 20 µA for good linearity.

Continuity Indicator

A comparator with a 200 mV threshold is connected

between IN HI (pin 33) and IN LO (pin 32). Whenever the

voltage between inputs is less than 200 mV, the

TELCOM SEMICONDUCTOR, INC.

5

IN HI

–

+

BUFFER

COM

6

TC7129

IN LO

CONT

–

200 mV

V

+

500 kΩ

TO DISPLAY

DRIVER

(NOT LATCHED)

7

Figure 14. Continuity Indicator Circuit

CONTINUITY output (pin 27) will be pulled HIGH, activating

the continuity annunciator on the display. The continuity

8 pin can also be used as an input to drive the continuity

annunciator directly from an external source. A schematic

of the input/output nature of this pin is shown in Figure 15.

3-243

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