Datasheet
Table Of Contents
- 1.0 Electrical characteristics
- 2.0 Pin Descriptions
- 3.0 Detailed Description
- 4.0 Typical Applications
- 4.1 TC7129 as a Replacement Part
- 4.2 Powering the TC7129
- 4.3 Connecting to External Logic
- 4.4 Temperature Compensation
- 4.5 RC Oscillator
- 4.6 Measuring Techniques
- 4.7 Dual-Slope Conversion
- 4.8 Successive Integration
- 4.9 Digital Auto-Zeroing
- 4.10 Inside the TC7129
- 4.11 Integrator Section
- 4.12 Continuity Indicator
- 4.13 Common and Digital Ground
- 4.14 Low Battery
- 4.15 Sequence and Results Counter
- 4.16 Overrange and Underrange Outputs
- 4.17 LATCH/Hold
- 4.18 Display Driver
- 5.0 Packaging Information
- 6.0 Revision History
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2002-2012 Microchip Technology Inc. DS21459E-page 1
TC7129
Features:
• Count Resolution: ±19,999
• Resolution on 200 mV Scale: 10 V
• True Differential Input and Reference
• Low Power Consumption: 500 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
Applications:
• Full-Featured Multimeters
• Digital Measurement Devices
Device Selection Table
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 V 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.
Typical Application
Package
Code
Pin
Layout
Package
Temperature
Range
TC7129CPL Normal 40-Pin PDIP 0C to +70C
TC7129CKW Formed 44-Pin PQFP 0C to +70C
TC7129CLW – 44-Pin PLCC 0C to +70C
TC7129
1234567
8
9
1011
12
13141516171819
20
40
39
3837
36
3534
33
323130
29
28
27262524232221
9V
+
+
Low Battery
Continuity
V+
5 pF
120 kHz
10 pF
0.1 µF
20
kΩ
0.1
µF
100 kΩ
1 µF
0.1 µF
150 kΩ
10 kΩ
V+
V
IN
–
+
*
*
N
o
t
e
:
RC network between pins 26 and 28 is not required.
330 kΩ
4-1/2 Digit Analog-to-Digital Converters with
On-Chip LCD Drivers