MAX12900AATJ+ Ultra-Low-Power 4 mA to 20 mA Sensor Transmitter

Analog Devices' MAX12900AATJ+ is an ultra-low-power, integrated 4 mA to 20 mA sensor transmitter. This transmitter integrates ten building blocks into a small 5 mm x 5 mm package. It has two conditioner circuits for pulse-width modulated (PWM) inputs, two low-drift general purpose operational amplifiers (op amp), one zero-offset drift operational amplifier; two comparators, a power-up sequencer, a low-drift voltage reference, and also a wide input supply voltage LDO.

MAX12900AATJ+ converts PWM data from a microcontroller into current over a 4 mA to 20 mA loop with two, three, or four wire configurations.

The equivalent to an ultra-low-power, high-resolution, digital-to-analog converter (DAC) is realized with the combination of two-PWM signals received from a microcontroller, the two conditioner circuits, and an active filter built with the integrated low-power op amp. The outputs of the two conditioner circuits provide a stable PWM amplitude over voltage supply and temperature variation. The zero-offset operational amplifier and the low-drift voltage reference provide negligible error over wide temperature. The low-power operational amplifier and comparators provide building blocks for enhanced diagnostic features. A few examples of diagnostic features are supply rail monitoring, output current readback, open circuit and failure detection. The MAX12900AATJ+ comes in 5 mm x 5 mm 32-pin TQFN package and operates over a wide industrial temperature range of -40°C to +125°C. These features make it ideal for loop-powered smart sensor transmitters.