Seven 24-bit and 16-bit multi-channel, sensor analog front-ends (AFE) by National Semiconductor Corp, Santa Clara, CA, offer system designers a greater range of choices from high-performance to low-cost options that span channel configurations, current sources, and resolution. National’s LMP900xx sensor AFE integrated circuits (ICs) provide an easy-to-configure signal path solution for interfacing sensors to microcontrollers. They are targeted at precision sensing systems for applications that include medical and test and measurement.

The pin-compatible LMP900xx sensor AFEs expand on the LMP90100 released earlier this year. They team with National’s WEBENCH Sensor AFE Designer software tool and bench-top development system, enabling design engineers to attach a sensor, configure the signal path, optimize the design, and download configuration data to the sensor AFE for immediate prototyping.

System designers can choose from a family of pin-compatible LMP900xx sensor AFEs that meet their specific resolution, channel, and current source needs. The LMP900xx family features either a 24-bit or 16-bit sigma-delta ADC with a programmable input (mux) configuration that interfaces up to four differential inputs, or seven single-ended inputs in any combination of input types. The microcontroller interface is supplied through a standard SPI 4-wire serial interface with CRC data link error correction and seven general purpose I/O ports. Each IC is guaranteed over the -40°C to 125°C temperature range.

The LMP900xx IC’s true background calibration at all gains (1, 2, 4, 8, 16, 32, 64, and 128) eliminates offset and gain drift over time and temperature without disturbing the measured signal. Each channel is independently configurable for gain and sample rate, with automatic, manual, and single scan of selected channels. They also provide continuous background sensor diagnostics for detecting shorts, opens and out-of-range signals.

The LMP90099/98/97 24-bit multichannel sensor AFEs provide various channel configurations and are supplied with or without matched current sources.