LTC1292 Datasheet, PDF (1/24 Pages) Linear Technology – Single Chip 12-Bit Data Acquisition Systems

LTC1292/LTC1297
Single Chip 12-Bit
Data Acquisition Systems
FEATURES
s _{Built-In Sample-and-Hold}
s _{Single Supply 5V Operation}
s _{60kHz Maximum Throughput Rate (LTC1292)}
s _{Power Shutdown After Each Conversion (LTC1297)}
s _{Direct 3-Wire Interface to Most MPU Serial Ports and}
All MPU Parallel Ports
s _{Analog Inputs Common Mode to Supply Rails}
KEY SPECIFICATIO S
s _{Resolution: 12 Bits}
s _{Fast Conversion Time: 12µs Max Over Temp}
s _{Low Supply Current: 6.0mA}
s _{Shutdown Supply Current: 5µA (LTC1297)}
DESCRIPTIO
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 5µA, typically. The LTC1292 is capable
of digitizing signals at a 60kHz rate and with the device’s
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
DIFFERENTIAL
INPUTS
+
COMMON MODE
RANGE _–
0V TO 5V_*
CS
V_CC
+IN
CLK
LTC1297
1N4148
–IN
D_OUT
+ 22µF ^5V
TANTALUM
DO
MC68HC11
SCK
MISO
GND
V_REF
LT1027
+ _4.7µF
TANTALUM
8V TO 40V
1µF
*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
Power Supply Current
vs Sampling Frequency
10000
1000
100
10
1
1
10
100
1k
10k 100k
f_SAMPLE (Hz)
LTC1297• TA02
1