1
LTC1290
Single Chip 12-Bit Data
Acquisition System
12-Bit 8-Channel Sampling Data Acquisition System
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
V
CC
ACLK
SCLK
D
IN
D
OUT
CS
REF
+
REF
–
V
–
AGND
LTC1290
DIFFERENTIAL INPUT (+)
±5V COMMON MODE RANGE (–)
•
•
•
•
•
•
1k
SINGLE-ENDED INPUT
0V TO 5V OR ±5V
±15V OVERVOLTAGE RANGE*
TO AND FROM
MICROPROCESSOR
0.1µF
1N5817
–5V
22µF
TANTALUM
1N5817
1N4148
4.7µF
TANTALUM
1µF
LT
®
1027
5V
8V TO 40V
* 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
).
1290 • TA01
+
+
S
F
EA
T
U
RE
D
U
ESCRIPTIO
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.
LTCMOS is a trademark of Linear Technology Corporation.
KEY SPECIFICATIO S
U
■
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
■
Resolution: 12 Bits
■
Fast Conversion Time: 13µs Max Over Temp
■
Low Supply Current: 6.0mA
U
A
O
PP
L
IC
AT
ITY
P
I
CA
L
, LTC and LT are registered trademarks of Linear Technology Corporation.
