National Expands Sensor AFE Family

National Semiconductor Corp. has unveiled seven new 24-bit and 16-bit multi-channel sensor analog front-ends (AFE) that offer system designers a greater range of choices from high-performance to low-cost options that span channel configurations, current sources, and resolution. The LMP900xx sensor AFEs provide an easy to configure signal path solution for interfacing sensors to microcontrollers. The devices are targeted at precision sensing systems used to monitor and control temperature, pressure, load, force, motion/position and voltage in industrial, medical, and test and measurement applications.

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. Weeks or months of design are reduced to just minutes using National’s integrated hardware/software development system.

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 4-differential inputs, or 7-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 multi-channel, sensor AFEs provide various channel configurations and are supplied with or without matched current sources:
• The LMP90099 provides 24-bit resolution, 4-differential and 7-single-ended inputs without current sources.
• The LMP90098 provides 24-bit resolution, 2-differential and 4-single-ended inputs with two matched current sources.
• The LMP90097 provides 24-bit resolution, 2-differential and 4-single-ended inputs without current sources.

The LMP90080/79/78/77 16-bit multi-channel, sensor AFEs provide various channel configurations and are supplied with or without matched current sources:
• The LMP90080 provides 16-bit resolution, 4-differential and 7-single-ended inputs with two matched current sources.
• The LMP90079 provides 16-bit resolution, 4-differential and 7-single-ended inputs without current sources.
• The LMP90078 provides 16-bit resolution, 2-differential and 4-single-ended inputs with two matched current sources.
• The LMP90077 provides 16-bit resolution, 2-differential and 4-single-ended inputs without current sources.

National Semiconductor