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TC7129
4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER
WITH ON-CHIP LCD DRIVERS
FEATURES
GENERAL DESCRIPTION
■ Count Resolution......................................... ±19,999
■ Resolution on 200 mV Scale.......................... 10 µV
■ True Differential Input and Reference
■ Low Power Consumption ...................500 µA at 9V
■ Direct LCD Driver for 4-1/2 Digits, Decimal Points,
Low-Battery Indicator, and Continuity Indicator
■ Overrange and Underrange Outputs
■ Range Select Input ............................................ 10:1
■ High Common-Mode Rejection Ratio ......... 110 dB
■ External Phase Compensation Not Required
The TC7129 is a 4-1/2 digit analog-to-digital converter
(ADC) that directly drives a multiplexed liquid crystal dis-
play (LCD). Fabricated in high-performance, low-power
CMOS, the TC7129 ADC is designed specifically for high-
resolution, battery-powered digital multimeter applications.
The traditional dual-slope method of A/D conversion has
been enhanced with a successive integration technique to
produce readings accurate to better than 0.005% of full
scale, and resolution down to 10 µV per count.
The TC7129 includes features important to multimeter
applications. It detects and indicates low-battery condition.
Acontinuityoutputdrivesanannunciatoronthedisplay, and
can be used with an external driver to sound an audible
alarm. Overrange and underrange outputs and a range-
change input provide the ability to create auto-ranging
instruments. For snapshot readings, the TC7129 includes a
latch-and-hold input to freeze the present reading. This
combination of features makes the TC7129 the ideal
choice for full-featured multimeter and digital measurement
applications.
ORDERING INFORMATION
Pin
Layout
Temperature
Range
Part No.
Package
TC7129CKW
TC7129CLW
TC7129CPL
Formed
—
44-Pin PQFP
44-Pin PLCC
40-Pin PDIP
0°C to +70°C
0°C to +70°C
0°C to +70°C
Normal
TYPICAL OPERATING CIRCUIT
LOW BATTERY
CONTINUITY
+
V
5 pF
20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
120 kHz
TC7129
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
330 kΩ
*
0.1 µF
10 pF
0.1
+
µF
20
0.1 µF
1 µF
150 kΩ
kΩ
TC04
+
V
10 kΩ
+
100 kΩ
9V
+
–
V
IN
NOTE:
RC network between pins 26 and 28 is not required.
*
TC7129-5 10/18/96
TELCOM SEMICONDUCTOR, INC.
3-231
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
