GPC150

Features:

`Three operating modes: 12-bit + sign, 8-bit + sign, and "watchdog"
`Single-ended or differential inputs
`Built-in Sample-and-Hold and 2.5V bandgap reference
`Instruction RAM and event sequencer
`8-channel (LM12(H)458), 4-channel (LM12454) multiplexer
`32-word conversion FIFO
`Programmable acquisition times and conversion rates
`Self-calibration and diagnostic mode
`8- or 16-bit wide databus dmicroprocessor or DSP interface


Application

·Data Logging
·Instrumentation
·Process Control
·Energy Management
·Inertial Guidance


Description

The LM12454, LM12458, and LM12H458 are highly integrated Data Acquisition Systems. Operating on just 5V, they combine a fully-differential self-calibrating (correcting linearity and zero errors) 13-bit (12-bit + sign) analog-to-digital converter (ADC) and sample-and-hold (S/H) with extensive analog functions 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 RAM can store the conversion sequence for up to eight acquisitions through the LM12(H)458's eight-input multiplexer. The LM12454 has a four-channel multiplexer, a differential multiplexer output, and a differential S/H input. The LM12454 and LM12(H)458 can also operate with 8-bit + sign resolution and in a supervisory "watchdog" mode that compares an input signal against two programmable limits.

Programmable acquisition times and conversion rates are possible through the use of internal clock-driven timers. The reference voltage input of LM12454, LM12458, and LM12H458 can be externally generated for absolute or ratiometric operation or can be derived using the internal 2.5V bandgap reference.

All registers, RAM, and FIFO LM12454, LM12458, and LM12H458 are directly addressable through the high speed microprocessor interface to either an 8-bit or 16-bit databus. The LM12454 and LM12(H)458 include a direct memory access (DMA) interface for high-speed conversion data transfer.