ADS7871
SLAS370C − APRIL 2002 − REVISED OCTOBER 2004
14ĆBIT, 48ĆKSPS, DATA ACQUISITION SYSTEM WITH ANALOGĆTOĆDIGITAL
CONVERTER, MUX, PGA, AND REFERENCE
FEATURES
D PGA Gains: 1, 2, 4, 5, 8, 10, 16, 20 V/V
D Programmable Input (Up to 4-Channel
Differential/Up to 8-Channel Single-Ended or
Some Combination)
D 1.15-V, 2.048-V, or 2.5-V Internal Reference
D SPI/DSP Compatible Serial Interface
(≤ 20 MHz)
D Throughput Rate: 48 kSamples/sec
D Error Overload Indicator
D Programmable Output 2s Complement/Binary
D 2.7-V to 5.5-V Single Supply Operation
D 4-Bit Digital I/O Via Serial Interface
D Pin-Compatible With ADS7870
D SSOP-28 Package
APPLICATIONS
D Portable Battery-Powered Systems
D Low-Power Instrumentation
D Low-Power Control Systems
D Smart Sensor Applications
DESCRIPTION
The ADS7871 (US patents 6140872, 6060874) is a
complete low power data acquisition system on a single
chip. It consists of a 4-channel differential/8-channel
single-ended multiplexer, precision programmable gain
amplifier, 14-bit successive approximation analog-to-
digital (A/D) converter, and a precision voltage reference.
The programmable-gain amplifier provides high input
impedance, excellent gain accuracy, good common-mode
rejection, and low noise.
For many low-level signals, no external amplification or
impedance buffering is needed between the signal source
and the A/D input.
The offset voltage of the PGA is auto-zeroed. Gains of 1,
2, 4, 5, 8, 10, 16, and 20 V/V allow signals as low as 125
mV to produce full-scale digital outputs.
The ADS7871 contains an internal reference, which is
trimmed for high initial accuracy and stability vs
temperature. Drift is typically 10 ppm/°C. An external
reference can be used in situations where multiple
ADS7871s share a common reference.
The serial interface allows the use of SPI, QSPI,
Microwire, and 8051-family protocols, without glue logic.
VREF
LN0
LN1
LN2
LN3
LN4
LN5
LN6
LN7
MUX
I/O0
I/O1
Digital
I/O2
I/O
I/O3
REF
BUFIN
BUFOUT/REFIN
Oscillator
+
_PGA
14-BIT
A/D
Registers
Serial
Interface
CCLK
OSC ENABLE
BUSY
CONVERT
RESET
RISE/FALL
CS
SCLK
DIN
DOUT
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PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright 2002−2004, Texas Instruments Incorporated
