TC7129 Datasheet, PDF (1/15 Pages) TelCom Semiconductor, Inc – 4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH ON-CHIP LCD DRIVERS

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TC7129
4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER
WITH ON-CHIP LCD DRIVERS
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FEATURES
GENERAL DESCRIPTION
s Count Resolution ......................................... ±19,999
s Resolution on 200 mV Scale .......................... 10 µV
s True Differential Input and Reference
s Low Power Consumption ................... 500 µA at 9V
s Direct LCD Driver for 4-1/2 Digits, Decimal Points,
Low-Battery Indicator, and Continuity Indicator
s Overrange and Underrange Outputs
s Range Select Input ............................................ 10:1
s High Common-Mode Rejection Ratio ......... 110 dB
s External Phase Compensation Not Required
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
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-
3 ^{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
4 ^{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.
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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
TC7129
120 kHz
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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
1 µF
150 kΩ
+ ^{10 kΩ}
9V
+
0.1
µF
20
kΩ
100 kΩ
TC04
0.1 µF
10 pF
V+
–
+
VIN
* NOTE: RC network between pins 26 and 28 is not required.
TELCOM SEMICONDUCTOR, INC.
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TC7129-5 10/18/96
3-231