RC4391

www.fairchildsemi.com RC4391 Inverting and Step-Down Switching Regulator Features Versatile — Inverting function (+ to -) Step-down function Adjustable output voltage Regulates supply changes Micropower — Low quiescent current — 170 mA Wide supply range — 4V to 30V High performance — High switch current — 375 mA High efficiency — 70% typically Low battery detection capability 8-lead mini-DIP or S.O. package Description Fairchild Semiconductor’s RC4391 is a monolithic switch mode power supply controller for micropower circuits. The RC4391 integrates all the active functions needed for low power switching supplies, including oscillator, switch, reference and logic, into a small package. Also, the quiescent supply current drawn by the RC4391 is extremely low; this combination of low supply current, function, and small package make it adaptable to a variety of miniature power supply applications. The RC4391 complements another Fairchild Semiconductor switching regulator IC, the RC4190. The RC4190 is dedicated to step-up (VOUT > VIN) applications, while the RC4391 was designed for inverting (VOUT = -VIN) and step-down (VOUT < VIN) applications. Between the two devices the ability to create all three basic switching regulator configurations is assured. Refer to the RC4190 data sheet for information on step-up applications. The functions provided are: Block Diagram RC4391 LBR C2 Q2 C1 VFB Squarewave oscillator (adjustable externally) Bandgap voltage referen...