The MAX35104 is a gas flow meter system-on-chip (SoC) targeted as an analog front-end solution for the ultrasonic gas meter and medical ventilator markets. With a time measurement accuracy of 700ps and automatic differential time of flight (TOF), the device makes for simplified computation of gaseous flow.

Power consumption is the lowest available with ultra-low 62µA time-of-flight measurement and 125nA duty-cycled temperature measurement. Multi-hit (up to six per wave) capability with stop-enable windowing allows the device to be fine-tuned for the application. Internal analog switches, a configurable three-stage integrated operational amplifier chain amplifier, and an ultra-low input offset comparator provide the analog interface and control for a minimal electrical bill of material solution. A programmable high-voltage (up to 30V) pulse launcher provides up to 19dB of transducer launch amplitude adjustment to compensate for transducer aging and temperature, pressure, humidity affects. Early edge detection ensures measurements are made with consistent wave patterns to greatly improve accuracy and eliminate erroneous measurements. Built-in arithmetic logic unit provides TOF difference measurements and programmable receiver hit accumulators to minimize the host microprocessor access. For temperature measurement, the device supports a single 2-wire PT1000 platinum resistive temperature detector (RTD) or NTC thermistor. A simple 4-wire SPI interface allows any microcontroller to effectively configure the device for its intended measurement.

Applications

• Medical Ventilators
• Ultrasonic Gas Meters