R1211x Series


Data Sheet / Flyer
Data Sheet * Flyer

The R1211x is a CMOS-based PWM step-up DC/DC converter controller with low supply current. The R1211x consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a reference current unit, a protection circuit, and an under voltage lockout (UVLO) circuit. A low ripple and high efficiency step-up DC/DC converter can be configured by only adding few external components, such as an inductor, a diode, a power MOSFET, divider resisters, and capacitors. The R1211x002B/D has a built-in phase compensation, while the R1211x002A/C can set a phase compensation externally. The R1211x002B/D has stand-by mode. The max duty cycle is internally fixed at 90% typically. A soft-start function is built-in, and a soft-starting time is set at 9 ms typically (R1211x002A/B, 700 kHz) or 10.5 ms typically (R1211xC/D, 300 kHz). The R1211x has a latch-type protection circuit, which latches the external driver in off-state if the maximum duty cycle continues for a specified time after soft-starting time. The protection delay time can be set with an external capacitor. To release the protection, turn the power off and back on (power source voltage lower than UVLO detector threshold) or make the device into standby mode and back to active mode using the CE pin.

Input Voltage Range 2.5V to 6.0V
Oscillator Frequency (PWM control) 300kHz, 700kHz
Maximum Duty Cycle Typ. 90%
Standby Current Typ. 0µA (R1211x002B/D)
Feedback Voltage 1.0V
Feedback Voltage Accuracy ±1.5%
UVLO Threshold Level Typ. 2.2V (Hysteresis Typ. 0.13V)
Feedback Voltage Temperature Coefficient ±150ppm/°C
Built-in Latch-type Protection Circuit Protection delay time can be set with an external capacitor
Packages SON-6, SOT-23-6W
  • Constant Voltage Power Source for Portable Equipment
  • Constant Voltage Power Source for LCD and CCD

Data Sheet Flyer Package Info. Mark Info. Quality Assurance Data
R1211x Series
R1211x Series SOT-23-6W R1211N Reliability
SON-6 R1211D Reliability

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