The ADP2370/ADP2371 are high efficiency， low quiescent current， 800 mA buck （step-down） dc-to-dc converters in small 8-lead， 3 mm × 3 mm LFCSP （QFN） packages. The total solution requires only three tiny external components. The buck regulator uses a proprietary high speed current mode， constant frequency PWM control scheme for excellent stability and transient response. The need for an external rectifier is eliminated by using a high efficiency synchronous rectifier architecture. To ensure the longest battery life in portable applications， the ADP2370/ADP2371 employ a power saving variable frequency mode that reduces the switching frequency under light load conditions. The ADP2370/ADP2371 operate from input voltages of 3.2 V to 15 V allowing the use of multiple alkaline/NiMH， lithium cells， or other standard power sources. The ADP2370/ADP2371 offer multiple options for setting the operational frequency. The ADP2370/ADP2371 can be synchronized to a 600 kHz to 1.2 MHz external clock or it can be forced to operate at 600 kHz or 1.2 MHz via the FSEL pin. The ADP2370/ ADP2371 can be forced to operate in PWM mode （FPWM） when noise considerations are more important than efficiency.