National Semiconductor today introduced two configurable sensor analog front-end (AFE) ICs, he LMP91000, presented as the industry’s first fully configurable potentiostat for low-power chemical sensing applications and the LMP90100, said to be the industry’s first 24-bit, 4-channel programmable sensor that allows calibration at all gains and sample rates without interrupting the signal path.
The LMP91000 measures current in a potentiostat that is proportional to the gas concentration. It generates an output voltage proportional to the cell current using a transimpedance amplifier. Transimpedance gain is user programmable through an I2C compatible interface, allowing the LMP91000 to support toxic gas sensitivities over a range of 0.5 nA/ppm to 9.5 nA/ppm. Low power makes the LMP91000 suitable for battery-operated systems, as well as 4 mA to 20 mA transmitter applications. The cell voltage and cell output gain are user-selectable using on-board programmability.
The LMP90100 is an integrated, multi-channel sensor AFE. The device features a 24-bit Sigma Delta Analog-to-Digital Converter (ADC) with a low-noise programmable gain amplifier and a fully differential high impedance analog input multiplexer.
An interesting feature of the LMP90100 is continuous background sensor diagnostics, allowing the detection of open and short circuit conditions and out-of-range signals, without requiring user intervention, resulting in enhanced system reliability. The LMP90100 draws less than 0.7 mA on average and is guaranteed over the entire -40 degrees C to 125 degrees C temperature range, making it well suited for temperature transmitter or 4 mA to 20 mA applications
When used with National’s WEBENCH Sensor AFE Designer the design engineer can select a sensor, design and configure the solution and download configuration data to the sensor AFE. A typical sensing application that today may require several boards and up to 25 components is reduced to just one IC.
According to National AFE products targeting faster and higher performance applications and expanding into other markets such as medical apps will be introduced in the coming year.
Offered in a 28-pin TSSOP package, National’s LMP90100 is priced at $4.95 in 1,000-unit quantities. The LMP91000 is offered in a 14-pin LLP package and priced at $3.95 in 1,000-unit quantities.