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LM12438 Datasheet 12-Bit + Sign Data Acquisition System

Manufacturer: National Semiconductor (now Texas Instruments)

Download the LM12438 datasheet PDF. This datasheet also includes the LM12434 variant, as both parts are published together in a single manufacturer document.

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Note: The manufacturer provides a single datasheet file (LM12434-NationalSemiconductor.pdf) that lists specifications for multiple related part numbers.

General Description

The LM12434 and LM12 L 438 are highly integrated Data Acquisition Systems Operating on 3V to 5V they combine a fully-differential self-calibrating (correcting linearity and zero errors) 13-bit (12-bit a sign) analog-to-digital converter (ADC) and sample-and-hold (S H) with extensive analog and digital functionality Up to 32 consecutive conversions using two’s complement format can be stored in an internal 32-word (16-bit wide) FIFO data buffer An internal 8-word instruction RAM can store the conversion sequence for up to eight acquisitions through the LM12 L 438’s eight-input multiplexer The LM12434 has a four-channel multiplexer a differential multiplexer output and a differential S H input The LM12434 and LM12 L 438 can also operate with 8-bit a sign resolution and in a supervisory ‘‘watchdog’’ mode that compares an input signal against two programmable limits Acquisition times and conversion rates are programmable through the use of internal clock-driven timers The differential reference voltage inputs can be externally driven for absolute or ratiometric operation All registers RAM and FIFO are directly accessible through the high speed and flexible serial I O interface bus The serial interface bus is user selectable to interface with the following protocols with zero glue logic MICROWIRE PLUSTM Motorola’s SPI QSPI Hitachi’s SCI 8051 Family’s Serial Port (Mode 0) I2C and the TMS320 Family’s Serial Port An evaluation kit for demonstrating the LM12434 and LM12 L 438 is available TRI-STATE is a registered trademark of National Semiconductor Corporation MICROWIRE PLUSTM is a trademark of National Semiconductor Corporation Windows is a registered trademark of Microsoft Corporation Key Specifications fCLK e 8 MHz L fCLK e 6 MHz Y Resolution 12-bit

Overview

LM12434 LM12 L 438 12-Bit a Sign Data Acquisition System with Serial I O and Self-Calibration July 1995 LM12434 LM12 L 438 12-Bit a Sign Data Acquisition System with Serial I O and Self-Calibration.

Key Features

  • Y Three operating modes 12-bit a sign 8-bit a sign and ‘‘watchdog’’ comparison mode Y Single-ended or differential inputs Y Built-in Sample-and-Hold Y Instruction RAM and event sequencer Y 8-channel (LM12 L 438) or 4-channel (LM12434) multiplexer Y 32-word conversion FIFO Y Programmable acquisition times and conversion rates Y Self-calibration and diagnostic mode Y Power down output for system power management Y Read while convert capability for maximum through-put rate.