A Monolithic Pulse-Proportional Servo IC for Radio Control Applications

Pulse-proportional servo systems find a wide range of applications in many consumer products, such as radio controlled model airplanes and toys, as well as the remotely-controlled appliances. This wide spread acceptance of radio controlled consumer products has been possible by the advent of low cost monolithic IC´s which greatly reduce the cost and complexity of such servo systems. This paper describes the design and the performance of a new pulse-proportional servo amplifier specifically designed for radio controlled consumer products. The monolithic IC is designed to control a shaft position in direct proportion to the input pulse-width. The circuit can directly drive servo motors requiring up to 350 mA of drive current. This drive capability can be boosted to in excess of 1/2 amp with the addition of two external PNP transistors.