TC7129 Datasheet, PDF (1/24 Pages) TelCom Semiconductor, Inc – 4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH ON-CHIP LCD DRIVERS

TC7129
4-1/2 Digit Analog-to-Digital Converters with
On-Chip LCD Drivers
Features
• Count Resolution: ±19,999
• Resolution on 200mV Scale: 10µV
• True Differential Input and Reference
• Low Power Consumption: 500µA at 9V
• Direct LCD Driver for 4-1/2 Digits, Decimal Points,
Low Battery Indicator, and Continuity Indicator
• Over Range and Under Range Outputs
• Range Select Input: 10:1
• High Common Mode Rejection Ratio: 110dB
• External Phase Compensation Not Required
Applications
• Full Featured Multimeters
• Digital Measurement Devices
Device Selection Table
Package
Code
TC7129CPL
TC7129CKW
TC7129CLW
Pin
Layout
Normal
Formed
–
Package
40-Pin PDIP
44-Pin PQFP
44-Pin PLCC
Temperature
Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
General Description
The TC7129 is a 4-1/2 digit analog-to-digital converter
(ADC) that directly drives a multiplexed liquid crystal
display (LCD). Fabricated in high performance, low
power CMOS, the TC7129 ADC is designed specifi-
cally for high resolution, battery powered digital multi-
meter applications. The traditional dual slope method
of A/D conversion has been enhanced with a succes-
sive integration technique to produce readings accu-
rate to better than 0.005% of full scale, and resolution
down to 10µV per count.
The TC7129 includes features important to multimeter
applications. It detects and indicates low battery condi-
tion. A continuity output drives an annunciator on the
display, and can be used with an external driver to
sound an audible alarm. Over range and under range
outputs and a range change input provide the ability to
create auto-ranging instruments. For snapshot read-
ings, 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.
Typical Application
Low Battery
Continuity
V+
5pF
20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
TC7129
120kHz
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
330kΩ
*
0.1µF
1µF
150kΩ
+ ^10kΩ
9V
+
0.1
µF
20
kΩ
0.1µF
10pF
V+
100kΩ
–
+ ^{*Note: RC network between Pins 26 and 28 is not required.}
V_IN
© 2002 Microchip Technology Inc.
DS21459B-page 1