LTC1292/LTC1297
Single Chip 12-Bit
Data Acquisition Systems
FEATURES
s
s
s
s
s
DESCRIPTIO
s
Built-In Sample-and-Hold
Single Supply 5V Operation
60kHz Maximum Throughput Rate (LTC1292)
Power Shutdown After Each Conversion (LTC1297)
Direct 3-Wire Interface to Most MPU Serial Ports and
All MPU Parallel Ports
Analog Inputs Common Mode to Supply Rails
KEY SPECIFICATIO S
s
s
s
s
Resolution: 12 Bits
Fast Conversion Time: 12碌s Max Over Temp
Low Supply Current: 6.0mA
Shutdown Supply Current: 5碌A(chǔ) (LTC1297)
The LTC1292/LTC1297 are data acquisition systems that
contain a 12-bit, switched-capacitor successive approxi-
mation A/D, a differential input, sample-and-hold on the
(+) input, and serial I/O. When the LTC1297 is idle between
conversions it automatically powers down reducing the
supply current to 5碌A(chǔ), typically. The LTC1292 is capable
of digitizing signals at a 60kHz rate and with the device鈥檚
excellent AC characteristics, it can be used for DSP appli-
cations. All these features are packaged in an 8-pin DIP
and are made possible using LTCMOS
TM
switched-capaci-
tor technology.
The serial I/O is designed to communicate without external
hardware to most MPU serial ports and all MPU parallel
I/O ports allowing data to be transmitted over three wires.
Because of their accuracy, ease of use and small package
size these devices are well suited for digitizing analog
signals in remote applications where minimum number of
interconnects and power consumption are important.
LTCMOS is trademark of Linear Technology Corporation
TYPICAL APPLICATI
12-Bit Differential Input Data Acquisition System
10000
CS
DIFFERENTIAL
INPUTS
COMMON MODE
RANGE
0V TO 5V
*
V
CC
CLK
1N4148
+
+
鈥?/div>
+IN
SCK
MISO
LT1027
8V TO 40V
1碌F
LTC1297
鈥揑N
D
OUT
GND
V
REF
AVERAGE I
CC
(碌A(chǔ))
5V
22碌F
TANTALUM
DO
MC68HC11
+
4.7碌F
TANTALUM
*FOR OVERVOLTAGE PROTECTION LIMIT THE INPUT CURRENT TO 15mA
PER PIN OR CLAMP THE INPUTS TO V
CC
AND GND WITH 1N4148 DIODES.
CONVERSION RESULTS ARE NOT VALID WHEN ANY INPUT IS OVERVOLTAGED
(V
IN
< GND OR V
IN
> V
CC
). SEE SECTION ON OVERVOLTAGE PROTECTION IN
THE APPLICATIONS INFORMATION.
LTC1292/7 TA01
U
Power Supply Current
vs Sampling Frequency
1000
100
10
1
1
10
1k
100
f
SAMPLE
(Hz)
10k
100k
LTC1297鈥?TA02
UO
U
1
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