LM12454 Datasheet, PDF (1/43 Pages) National Semiconductor (TI) – 12-Bit Sign Data Acquisition System with Self-Calibration

LM12454, LM12458, LM12H458
www.ti.com
SNAS079A – MAY 2004 – REVISED FEBRUARY 2006
LM12454/LM12458/LM12H458 12-Bit + Sign Data Acquisition System with Self-Calibration
Check for Samples: LM12454, LM12458, LM12H458
FEATURES
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•23 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 multiplexer
• 32-word conversion FIFO
• Programmable acquisition times and
conversion rates
• Self-calibration and diagnostic mode
• 8- or 16-bit wide data bus microprocessor or
DSP interface
APPLICATIONS
• Data Logging
• Instrumentation
• Process Control
• Energy Management
• Inertial Guidance
KEY SPECIFICATIONS
• Resolution: 12-bit + sign or 8-bit + sign
• 13-bit conversion time: 8.8 μs, 5.5 μs (H) (max)
• 9-bit conversion time: 4.2 μs, 2.6 μs (H) (max)
• 13-bit Through-put rate:
– 88k samples/s (min)
– 140k samples/s (H) (min)
• Comparison time: 2.2 μs (max)
– ("watchdog” mode): 1.4 μs (H) (max)
• ILE: ±1 LSB (max)
• V_IN range: GND to VA ⁺
• Power dissipation: 30 mW, 34 mW (H) (max)
• Stand-by mode: 50 μW (typ)
• Single supply: 3V to 5.5V
DESCRIPTION
The 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 obsolete LM12454 has a four-
channel multiplexer, a differential multiplexer output,
and a differential S/H input. The 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 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 are directly addressable
through the high speed microprocessor interface to
either an 8-bit or 16-bit data bus. The LM12(H)458
includes a direct memory access (DMA) interface for
high-speed conversion data transfer.
Additional applications information can be found in
applications notes AN-906, AN-947 and AN-949.
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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2
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3
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2006, Texas Instruments Incorporated