TC7135_04 Datasheet, PDF (1/24 Pages) Microchip Technology – 4-1/2 Digit A/D Converter

TC7135
4-1/2 Digit A/D Converter
Features
• Low Rollover Error: ±1 Count Max
• Nonlinearity Error: ±1 Count Max
• Reading for 0V Input
• True Polarity Indication at Zero for Null Detection
• Multiplexed BCD Data Output
• TTL-Compatible Outputs
• Differential Input
• Control Signals Permit Interface to UARTs and
Microprocessors
• Blinking Display Visually Indicates Overrange
Condition
• Low Input Current: 1 pA
• Low Zero Reading Drift: 2 µV/°C
• Auto-Ranging Supported with Overrange and
Underrange Signals
• Available in PDIP and Surface-Mount Packages
General Description
The TC7135 4-1/2 digit A/D Converter (ADC) offers
50 ppm (1 part in 20,000) resolution with a maximum
nonlinearity error of 1 count. An auto-zero cycle
reduces zero error to below 10 µV and zero drift to
0.5 µV/°C. Source impedance errors are minimized by
a 10 pA maximum input current. Rollover error is
limited to ±1 count.
Microprocessor-based measurement systems are
supported by the BUSY, STROBE and RUN/HOLD
control signals. Remote data acquisition systems with
data transfer via UARTs are also possible. The addi-
tional control pins and multiplexed BCD outputs make
the TC7135 the ideal converter for display or
microprocessor-based measurement systems.
Applications
• Precision Analog Signal Processor
• Precision Sensor Interface
• High Accuracy DC Measurements
Functional Block Diagram
Set V_REF = 1V
5V
TC7135
V_REF IN
100 kΩ
1
2
V–
REF IN
UNDERRANGE
OVERRANGE
28
27
3 _ANALOG
26
COMMON ^STROBE
Analog GND
0.47 µF
1 µF
4
INT OUT
RUN/HOLD ²⁵
5
6
AZ IN
DIGTAL GND
BUFF OUT POLARITY
24
23
Signal
Input
100 kΩ
100 kΩ ₇
1 µF ₈
9
C_REF–
C_REF+
–INPUT
22
CLOCK IN
21
BUSY
(LSD) D1 ²⁰
0.1 µF
+5V
10 _+INPUT
11 _V+
D2 ¹⁹
D3 ¹⁸
12 _{D5 (MSD)}
D4 ¹⁷
13 _{B1 (LSB)}
(MSB) B8 ¹⁶
14 _B2
B4 ¹⁵
Clock Input
120 kHz
 2004 Microchip Technology Inc.
DS21460C-page 1