RICOH R1225N SERIES PWM/VFM step-down DC/DC controller Manual
User Manual
The R1225N Series are CMOS-based PWM step-down DC/DC Converter controllers with low supply current. Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a soft-start circuit, a latch-type protection circuit, a PWM/VFM alternative circuit, a chip enable circuit, a phase compensation circuit, and an input voltage detect circuit. Further, protection circuit delay time adjuster circuit, and resistors for voltage detection are included. A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with some external components, or a power-transistor, an inductor, a diode and capacitors.