LTC1287 3V Single Chip 12-Bit Data Acquisition System UFEATURESDESCRIPTIO ■ Single Supply 3.3V Operation The LTC®1287 is a 3V data acquisition component which ■ Built-In Sample-and-Hold contains a serial I/O successive approximation A/D con- ■ Direct 3-Wire Interface to Most MPU Serial Ports and verter. The device specifications are guaranteed at a All MPU Parallel Ports supply voltage of 2.7V. It uses LTCMOSTM switched ca- ■ 30kHz Maximum Throughput Rate pacitor technology to perform a 12-bit unipolar, A/D conversion. The differential input has an on-chip sample- UKEY SPECIFICATIO S and-hold on the (+) input. The serial I/O is designed to communicate without external ■ Minimum Guaranteed Supply Voltage: 2.7V hardware to most MPU serial ports and all MPU parallel ■ Resolution: 12 Bits I/O ports allowing data to be transmitted and received over ■ Fast Conversion Time: 24µs Max Over Temp. three wires. The low voltage operating capability and the ■ Low Supply Current: 1.0mA low power consumption of this device make it ideally suited for battery applications. Given the ease of use, small U package size and the minimum number of interconnects APPLICATIO S for I/O, the LTC1287 can be used for remote sensing ■ applications. Battery-Powered Instruments ■ Data Logger , LTC and LT are registered trademarks of Linear Technology Corporation. LTCMOS is a trademark of Linear Technology Corporation ■ Data Acquisition Modules UTYPICAL APPLICATIO3V Differential Input Data Acquisition System 22µF TANTALUM + INL with VREF = 1.2V 1.0 CS VCC 3V 10k LITHIUM DIFFERENTIAL INPUTS + +IN CLK COMMON MODE RANGE LTC1287 0.5 0V TO VCC* – –IN DOUT GND VREF 0 + LT1004-1.2 22µF ERROR (LSB) TANTALUM –0.5 TO AND FROM MPU –1.0 0 512 1024 1536 2048 2560 3072 3584 4096 * FOR OVERVOLTAGE PROTECTION, LIMIT THE INPUT CURRENT TO 15mA PER PIN OR CLAMP THE INPUTS TO V CODE CC AND GND WITH 1N4148 DIODES. CONVERSION RESULTS ARE NOT VALID WHEN THE SELECTED CHANNEL OR LTC1287 TA02 OTHER CHANNEL IS OVERVOLTAGED (VIN < GND OR VIN > VCC). SEE SECTION ON OVERVOLTAGE PROTECTION IN THE APPLICATIONS INFORMATION. 1287 TA01 1287fa 1