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 fixed internally in the R1234Dxx1A/B types. While in the R1234D001C/D types, Output Voltage is adjustable with external divider resistors.

FEATURES

• Supply Current ..................................................Typ. 230µA (R1234Dxx1A/C)

Typ. 250µA (R1234Dxx1B/D)

• Standby Current ................................................Typ. 0µA

• Input Voltage Range ........................................ 2.4V to 5.5V (ABSOLUTE MAXIMUM : 6.5V)

• Output Voltage Range.......................................2.2V to 3.3V (R1234Dxx1A/B)

0.8V to VIN (R1234Dxx1C/D)

• Output Voltage Accuracy...................................±2.0 (R1234DxxA/B)

• Oscillator Frequency.........................................Typ. 500kHz (R1234Dxx1A/C)

Typ. 800kHz (R1234Dxx1B/D)

• Built-in Driver ON Resistance ...........................Pch 0.4Ω ,Nch 0.6Ω (VIN=3V)

• Control mode switch .........................................MODE pin=”L”: PWN

MODE pin=”H”: VFM

• Efficiency...........................................................Typ. 90

• Package ............................................................SON-8

• Built-in Soft-start Function.................................Typ. 1.5ms

• Latch-type Protection Function .........................Typ. 1.5ms

• Built-in Current Limit Circuit

APPLICATIONS

• Power source for portable equipment.