1
®
ADS7870
®
ADS7870
©1999 Burr-Brown Corporation PDS-1539A Printed in U.S.A. December, 1999
FEATURES
l 16-BIT DYNAMIC RANGE
l PGA GAINS: 1, 2, 4, 5, 8, 10, 16, 20V/V
l 4-CHANNEL DIFFERENTIAL/8-CHANNEL
SINGLE ENDED MULTIPLEXER
l 2.048V OR 2.5V INTERNAL REFERENCE
l FAST SERIAL INTERFACE
l HIGH THROUGHPUT RATE: 52ksamples/s
l ERROR/OVERLOAD INDICATOR
l 2.7V TO 5.5V SINGLE-SUPPLY OPERATION
l 4-BIT DIGITAL I/O VIA SERIAL INTERFACE
l SSOP-28 PACKAGE
12-Bit ADC, MUX, PGA and Internal Reference
DATA ACQUISITION SYSTEM
DESCRIPTION
The ADS7870
(1)
is a complete low-power data acquisi-
tion system on a single chip. It consists of a 4-channel
differential/8-channel single-ended multiplexer, preci-
sion programmable gain amplifier, 12-bit successive
approximation analog-to-digital converter and a preci-
sion 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.
APPLICATIONS
l PORTABLE/BATTERY POWERED
SYSTEMS
l LOW POWER INSTRUMENTATION
l LOW POWER CONTROL SYSTEMS
l SMART SENSOR APPLICATIONS
International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111
Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
ADS7870
REF
Serial
Interface
ADS7870
DIN
SCLK
CS
CONVERT
RESET
RISE/FALL
BUSY
DOUT
Clock
Divider
Oscillator
OSC ENABLE
CCLK
BUF
OUT
/REF
IN
BUF
IN
V
REF
12-Bit
A/D
BUF
MUX
8 Ch
(4 Ch Diff.)
Analog
Inputs
Digital
I/O
Registers
and
Control
I/O 0
I/O 1
I/O 2
I/O 3
PGA
The offset voltage of the PGA is auto zeroed. Gains of
1, 2, 4, 5, 8, 10, 16 and 20V/V provide 16-bit dynamic
range and allow signals as low as 125mV to produce full
scale digital outputs.
The ADS7870 contains an internal reference, which is
trimmed for high initial accuracy and stability vs tem-
perature. Drift is typically 10ppm/°C. An external refer-
ence 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.
NOTE: (1) Patent Pending.
For most current data sheet and other product
information, visit www.burr-brown.com