The LM12434 and LM12-L-438 are highly integrated data acquisition systems operating on 3V to 5V. They combine a fully-differential self-calibrating 13-bit (12-bit signed) analog-to-digital converter (ADC) and sample-and-hold (S&H) with extensive analog and digital functionality. Up to 32 consecutive conversions can be stored in an internal 32-word (16-bit wide) FIFO data buffer. An internal 8-word instruction RAM can store the conversion sequence for up to eight acquisitions through the LM12-L-438's eight-input multiplexer. The LM12434 has a four-channel multiplexer, a differential multiplexer output, and a differential S&H input. The LM12434 and LM12-L-438 can also operate with 8-bit signed resolution and in a supervisory 'watchdog' mode that compares an input signal against two programmable limits. Acquisition times and conversion rates are programmable through the use of internal clock-driven timers. The differential reference voltage inputs can be externally driven for absolute or ratiometric operation. All registers, RAM, and FIFO are directly accessible through the high-speed and flexible serial I/O interface bus. The serial interface bus is user selectable for interface connections.
The LM12434 and LM12438 are highly integrated data acquisition systems that operate from 3 V to 5 V. They combine a fully‑differential, self‑calibrating 13‑bit (12‑bit + sign) ADC with sample‑and‑hold, an internal FIFO, and programmable acquisition timing. The devices support multiple serial interfaces such as MICROWIRE/PLUS™, SPI, I²C, and 8051 serial ports without external glue logic.
The handbook provides functional diagrams, electrical specifications, pin descriptions, and detailed information on the digital and analog interfaces. It also includes performance characteristics, typical application notes, and guidelines for PCB layout and grounding.
| Resolution | 12‑bit + sign or 8‑bit + sign |
|---|---|
| Through‑put Rate | 140 k samples/s (minimum) |
| Package Type | 28‑Pin PLCC (or 28‑Pin Wide Body SO) |
| Multiplexer Channels | 4‑channel (LM12434) or 8‑channel (LM12438) |
The devices support three operating modes: 12‑bit + sign, 8‑bit + sign, and a watchdog comparison mode.
The LM12434 has a four‑channel multiplexer, while the LM12438 (LM12L438) provides an eight‑channel multiplexer.
The serial interface bus can be configured for MICROWIRE/PLUS™, SPI/GSPI, Hitachi SCI, 8051 serial port, I²C, or the TMS320 family serial port.