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.
●## Key Specifications
●(fCLK = 5 MHz; 8 MHz, H)
●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 ("watchdog" mode)| 2.2 µs (max),1.4 µs (H) (max)
●ILE| ±1 LSB (max)
●VIN range| GND to VA+
●Power Consumption| 30 mW, 34 mW (H) (max)
●Stand-by mode| 50 µW (typ)
●Single supply| 3V to 5.5V
● 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
