Overview: .. R5212D SERIES
Step-down DC/DC Converter with VR and Reset
NO.EA-128-0510 OUTLINE
The R5212D is CMOS-based PWM step-down DC/DC converter bined with a voltage regulator (VR) and a voltage detector (VD), with low supply current. Each of these ICs consists of an oscillator, a PWM control circuit, a voltage reference unit, an error amplifier, a soft-start circuit, a current limit circuit, a phase pensation circuit, a resistor net for voltage detect circuit, an output driver transistor, and so on. A low ripple, high efficiency step-down DC/DC converter can be easily posed of this IC with some external ponents, or an inductor, a diode, and capacitors. The oscillator frequency is 1.2MHz, therefore small inductor and capacitor can be used with this IC. Further, this IC equips the under voltage lockout function (UVLO). If the input voltage bees equal or less than 2.35V (Typ.), the output of DC/DC converter turns off. However, in the A/B version, embedded voltage regulator and detector continue to operate. In the C/D version, LDO output also turns off and only the voltage detector is working. The voltage regulator consists of a voltage reference unit, a resistor net for voltage detect circuit, an error amplifier, an output driver transistor, and so on. The input source voltage of the built-in voltage regulator is VIN pin (A/B version) or VOUT1 pin, the output of DC/DC converter (C/D version). The built-in voltage detector supervises the input voltage and the output is N-channel open drain. Power-on reset delay time is also included and internally set typically at 12ms (A/C version) or 50ms(B/D version).
