A PWM controller for extended temperature applications

Conventional pulse width modulated (PWM) switching power supplies are not suitable for operation at extended temperatures beyond 125°C. In virtually all power switching applications, mechanical apparatus is always attached to the power supply because the system mandates sufficient heat removal. The attachment is usually bulky and heavy compared with integrated circuit and electronics component. For commercial applications, power supply without a heat sink means a boost of power density. For aerospace applications, reduction or elimination of the weight and volume of the cooling system is extremely desirable. In recent years, there has been an increased demand for distributed engine and flight actuator electronics control. Commercial/military airplanes, supersonic and space vehicles benefit from the use of smart sensors and remote actuators. These ruggedized electronics must operate in harsh environments where active cooling is unavailable. Furthermore, ruggedized electronics have found other uses in the petroleum industry for geothermal instruments and data logging equipment. Such opportunities even extend to the automobile industry where electronic systems will be mandatory for improved fuel economy, smart braking, emission/exhaust monitoring and control. Perhaps the most challenging task for such ruggedized electronics is power supply design. This paper describes a new PWM power supply controller, a switch-mode ASIC (SMA) that has been developed to operate over the -55°C to +225°C temperature range