A 200 °C Custom CMOS Chipset for Distributed Control Applications

Abstract

Four integrated circuits (ICs) have been developed to provide sensing, actuation, and power conversion capabilities in a high-temperature (200 °C) distributed control environment. Patented high-temperature techniques facilitate designs in a conventional, low-cost, 0.5-μm bulk CMOS foundry process. The HHT104 eight-channel instrumentation IC measures LVDTs, RTDs, thermocouples, and other sensors with up to 12-bit resolution. Dual sigma-delta converters and independent, programmable gain allow simultaneous conversion of two differentialoutput sensors. The HHT212 current driver IC may be used to control two motors in full-bridge configuration or four independent half-bridge loads. Each channel is capable of driving up to 300 mA with 12-bit resolution. An internally-generated, temperature-stabilized current reference minimizes external components. The HHT250 is a quad load driver featuring an integrated PWM controller, push-pull outputs and flexible drive capability. The HHT301 quad-output switched-mode power supply IC implements a compact power solution for multi-voltage microprocessors, sensors, and actuators. The external part count is minimized using integrated output FETs and a voltage feedback topology. Bench tests confirmed device functionality and performance at ambient temperatures of 200 °C and junction temperatures up to 250 °C. A high-temperature development system was created using the four ICs and a DSP for actuator controller prototypes. A reference application was implemented using this system to measure an LVDT and drive a torque motor. The development system was tested for 4700 hours without any noticeable failure or performance degradation of the custom CMOS chipset.