R1211x Series


Data Sheet / Flyer
Data Sheet * Flyer

The R1211x Series are CMOS-based PWM step-up DC/DC converter controllers with low supply current.

Each of the R1211x Series 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, high efficiency step-up DC/DC converter can be composed of this IC with some external components, or an inductor, a diode, a power MOSFET, divider resisters, and capacitors.

Phase compensation has been made internally in the R1211x002B/D Series, while phase compensation can be made externally as for R1211x002A/C Series. B/D version has stand-by mode.

Max duty cycle is internally fixed typically at 90%. Soft start function is built-in, and Soft-starting time is set typically at 9ms(A/B, 700kHz version) or 10.5ms(C/D, 300kHz version). As for the protection circuit, after the soft-starting time, if the maximum duty cycle is continued for a certain period, the R1211x Series latch the external driver with its off state, or Latch-type protection circuit works.

The delay time for latch the state can be set with an external capacitor.

To release the protection circuit, restart with power-on (Voltage supplier is equal or less than UVLO detector threshold level), or once after making the circuit be stand-by with chip enable pin and enable the circuit again.

Input Voltage Range 2.5V to 6.0V
Oscillator Frequency (PWM control) 300kHz, 700kHz
Maximum Duty Cycle Typ. 90%
Standby Current Typ. 0µA (for B/D version)
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 Protction 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

All PDF files are less than 1MB unless otherwise stated.

  • Buy Products / Order Sample


Ricoh semiconductor products are available at those dealers.


Page Top