1
TC7129
4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER
WITH ON-CHIP LCD DRIVERS
FEATURES
s
s
s
s
s
s
s
s
s
Count Resolution .........................................
±
19,999
Resolution on 200 mV Scale .......................... 10
µ
V
True Differential Input and Reference
Low Power Consumption ................... 500
µ
A 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
2
3
4
5
GENERAL DESCRIPTION
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.
A continuity output drives an annunciator on the display, 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
Part No.
TC7129CKW
TC7129CLW
TC7129CPL
Pin
Layout
Formed
—
Normal
Package
44-Pin PQFP
44-Pin PLCC
40-Pin PDIP
Temperature
Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
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
6
120 kHz
330 kΩ
TC7129
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
*
0.1
µF
1
µF
150 kΩ
+
9V
–
10 kΩ
+
0.1
µF
10 pF
20
kΩ
TC04
0.1
µF
V+
7
100 kΩ
+
VIN
* NOTE:
RC network between pins 26 and 28 is not required.
TC7129-5 10/18/96
8
3-231
TELCOM SEMICONDUCTOR, INC.
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
