View r1234d-series datasheet:

R1234D SERIES PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier NO.EA-137-070221 OUTLINE The R1234D Series are CMOS-based PWM step-down DC/DC Converters with synchronous rectifier, 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, protection circuits, a protection against miss operation under low voltage (UVLO), PWM/VFM alternative circuit, a chip enable circuit, and a driver transistor. A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with only a few kinds of external components, or an inductor and capacitors. (As for R1234D001C/D types, divider resistors are also necessary.) In terms of Output Voltage, it is