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SBAS124C − DECEMBER 1999 − REVISED DECEMBER 2005
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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: 52 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 ADS7871
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 ADS7870 (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, 12-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 ADS7870 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
ADS7870s share a common reference.
The serial interface allows the use of SPI, QSPI,
Microwire, and 8051-family protocols, without glue logic.
12-BIT
A/D
MUX
Serial
Interface
SCLK
CS
Digital
I/O
I/O0
I/O2
I/O3
I/O1
LN0
LN2
LN3
LN1
LN4
LN6
LN7
LN5
Registers
PGA
_
+
RESET
RISE/FALL
DIN
DOUT
BUSY
CONVERT
BUFOUT/REFINBUFIN
Oscillator
CCLK
OSC ENABLE
REF
VREF
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 1999−2005, Texas Instruments Incorporated
QSPI and SPI are trademarks of Motorola, Inc.
Microwire is a trademark of National Semiconductor Corporation.
All other trademarks are the property of their respective owners.
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