LTC1290_1 Datasheet, PDF (1/32 Pages) Linear Technology – Single Chip 12-Bit Data Acquisition System

LTC1290
Single Chip 12-Bit Data
Acquisition System
FEATURES
■ _{Software Programmable Features}
– Unipolar/Bipolar Conversion
– Four Differential/Eight Single-Ended Inputs
– MSB- or LSB-First Data Sequence
– Variable Data Word Length
– Power Shutdown
■ _{Built-In Sample-and-Hold}
■ _{Single Supply 5V or ±5V Operation}
■ _{Direct Four-Wire Interface to Most MPU Serial Ports}
and All MPU Parallel Ports
■ _{50kHz Maximum Throughput Rate}
■ _{Available in 20-Lead PDIP and SO Wide Packages}
U
KEY SPECIFICATIO S
■ _{Resolution: 12 Bits}
■ _{Fast Conversion Time: 13µs Max Over Temp}
■ _{Low Supply Current: 6.0mA}
DESCRIPTIO
The LTC^®1290 is a data acquisition component which
contains a serial I/O successive approximation A/D con-
verter. It uses LTCMOS^TM switched capacitor technology
to perform either 12-bit unipolar or 11-bit plus sign bipolar
A/D conversions. The 8-channel input multiplexer can be
configured for either single-ended or differential inputs (or
combinations thereof). An on-chip sample-and-hold is
included for all single-ended input channels. When the
LTC1290 is idle it can be powered down with a serial word
in applications where low power consumption is desired.
The serial I/O is designed to be compatible with industry
standard full duplex serial interfaces. It allows either MSB-
or LSB-first data and automatically provides 2's comple-
ment output coding in the bipolar mode. The output data
word can be programmed for a length of 8, 12 or 16 bits.
This allows easy interface to shift registers and a variety of
processors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents, including 5287525.
TYPICAL APPLICATIO
12-Bit 8-Channel Sampling Data Acquisition System
SINGLE-ENDED INPUT
0V TO 5V OR ±5V
±15V OVERVOLTAGE RANGE*
1k
•
•
•
DIFFERENTIAL INPUT (+)
±5V COMMON MODE RANGE (–)
•
•
•
CH0
V_CC
CH1
ACLK
CH2
SCLK
CH3
D_IN
CH4
D_OUT
LTC1290
CH5
CS
CH6
REF ⁺
CH7
REF ^–
COM
V^–
+
22µF
TANTALUM
TO AND FROM
MICROPROCESSOR
5V
1N5817
1N4148
+
4.7µF
TANTALUM
–5V
LT^®1027
8V TO 40V
1µF
DGND
AGND
0.1µF
1N5817
1290 • TA01
* FOR OVERVOLTAGE PROTECTION ON ONLY ONE CHANNEL LIMIT THE INPUT CURRENT TO 15mA. FOR OVERVOLTAGE PROTECTION
ON MORE THAN ONE CHANNEL LIMIT THE INPUT CURRENT TO 7mA PER CHANNEL AND 28mA FOR ALL CHANNELS. (SEE SECTION ON
OVERVOLTAGE PROTECTION IN THE APPLICATIONS INFORMATION SECTION.) CONVERSION RESULTS ARE NOT VALID WHEN THE SELECTED
OR ANY OTHER CHANNEL IS OVERVOLTAGED (V_IN < V^– OR V_IN > V_CC).
1290fe
1