General Description
The MAX12900 is an ultra-low-power, highly integrated
4-20mA sensor transmitter. The MAX12900 integrates
ten building blocks in a small package: a wide input supply
voltage LDO, two conditioner circuits for pulse-widthmodulated
(PWM) inputs, two low-power, low-drift, generalpurpose
operational amplifiers (op amp) one wide bandwidth,
zero-offset drift operational amplifier; two diagnostic
comparators, a power-up sequencer with power good
output to allow for a smooth power-up, and a low-drift
voltage reference.
The MAX12900 converts PWM data from a microcontroller
into current over a 4-20mA loop with two, three, or fourwire
configurations.
The equivalent to an ultra-low-power, high-resolution,
digital-to-analog converter 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 wide bandwidth
amplifier, in combination with a discrete transistor,
converts a voltage input into a current output and allows
HART and Foundation Fieldbus H1 signal modulation.
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. Supply rail monitoring, output
current readback, open circuit and failure detection are a
few examples of diagnostic features. All these features,
as well as ultra-low-power and high accuracy make the
MAX12900 ideal for loop-powered smart sensor transmitters
for industrial application.
The MAX12900 is available in 5mm x 5mm 32-pin TQFN
package and operates over a wide industrial temperature
range of -40°C to +125°C.

Benefits and Features
● Wide Input Supply Range: 4.0V to 36V
● Ultra-Low-Power Consumption: 170μA (typ)
● High Linearity: 0.01% (Max Error)
● High Resolution: Up to 16 Bit
● Low Drift Voltage Reference: 10ppm/°C max
● Wide Temperature Range: -40°C to +125°C
● Small Package: 5mm x 5mm x 0.8mm 32-pin TQFN

Applications
● Loop-Powered 4-20mA Current Transmitter
● Smart Sensors
● Remote Instrumentation
● Industrial Automation and Process Control