PWM STEP-UP DC/DC CONTROLLER
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 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|
- ・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|
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