LM12L458 12-Bit + Sign Data Acquisition System with Self-Calibration
July 1999
LM12L458
12-Bit + Sign Data Acquisition System with
Self-Calibration
General Description
The LM12L458 is a highly integrated 3.3V Data Acquisition
System. It combines a fully-differential self-calibrating (cor-
recting 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 functional-
ity. Up to 32 consecutive conversions, using two鈥檚 comple-
ment 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 LM12L458鈥檚 eight-input multiplexer. The LM12L458 can
also operate with 8-bit + sign resolution and in a supervisory
鈥渨atchdog鈥?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.
All registers, RAM, and FIFO are directly addressable
through the high speed microprocessor interface to either an
8-bit or 16-bit databus. The LM12L458 includes a direct
memory access (DMA) interface for high-speed conversion
data transfer.
Key Specifications
(f
CLK
= 6 MHz)
n
Resolution
12-bit + sign or 8-bit + sign
n
13-bit conversion time
7.3 碌s
n
9-bit conversion time
3.5 碌s
n
13-bit Through-put rate
106k samples/s (min)
n
Comparison time (鈥渨atchdog鈥?mode)
1.8 碌s (max)
鹵
1 LSB (max)
n
ILE
n
V
IN
range
GND to V
A+
n
Power dissipation
15 mW (max)
n
Stand-by mode
5 碌W (typ)
n
Single supply
3V to 5.5V
Features
n
Three operating modes: 12-bit + sign, 8-bit + sign, and
鈥渨atchdog鈥?/div>
n
Single-ended or differential inputs
n
Built-in Sample-and-Hold
n
Instruction RAM and event sequencer
n
8-channel multiplexer
n
32-word conversion FIFO
n
Programmable acquisition times and conversion rates
n
Self-calibration and diagnostic mode
n
8- or 16-bit wide databus microprocessor or DSP
interface
n
CMOS compatible I/O
Applications
n
n
n
n
Data Logging
Process Control
Energy Management
Medical Instrumentation
TRI-STATE
廬
is a registered trademark of National Semiconductor Corporation.
AT
廬
is a registered trademark of International Business Machines Corporation.
漏 1999 National Semiconductor Corporation
DS011711
www.national.com
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