TC7129_06 Datasheet, PDF (1/28 Pages) Microchip Technology – 4-1/2 Digit Analog-to-Digital Converters 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 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
Applications:
• Full-Featured Multimeters
• Digital Measurement Devices
Device Selection Table
Package
Code
Pin
Layout
Package
TC7129CPL
TC7129CKW
TC7129CLW
Normal
Formed
–
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
Typical Application
Low Battery
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 10 μV 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. Overrange and underrange outputs,
along with 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.
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
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
+
0.1
µF
20
kΩ
150 kΩ
+
10 kΩ
9V
100 kΩ
0.1 µF
10 pF
V+
–
+
V_IN
*Note: RC network between pins 26 and 28 is not required.
© 2006 Microchip Technology Inc.
DS21459D-page 1