February 2006
LM12L458
12-Bit + Sign Data Acquisition System with
Self-Calibration
General Description
Key Specifications
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 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
LM12L458’s eight-input multiplexer. The LM12L458 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.
(fCLK = 6 MHz)
n Resolution
n Single supply
12-bit + sign or 8-bit + sign
+3V to +5.5V
n 13-bit conversion time
n 9-bit conversion time
n 13-bit Through-put rate
n Comparison time (“watchdog” mode)
n ILE
7.3 µs
3.5 µs
106k samples/s (min)
1.8 µs (max)
1 LSB (max)
15 mW (max)
5 µW (typ)
n Power Consumption
n Stand-by mode
Features
n Three operating modes: 12-bit + sign, 8-bit + sign, and
“watchdog”
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 LM12L458 includes a direct
memory access (DMA) interface for high-speed conversion
data transfer.
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
Additional applications information can be found in applica-
tions notes AN-906, AN-947 and AN-949.
n Programmable acquisition times and conversion rates
n Self-calibration and diagnostic mode
n 8- or 16-bit wide data bus microprocessor or DSP
interface
n CMOS compatible I/O
Applications
n Data Logging
n Process Control
n Energy Management
n Medical Instrumentation
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