DC/DC controller powers application processors
The R1272S generates an output voltage that is adjustable from 0.7 to 5.3V for driving external high-side and low-side NMOS transistors. The total circuit provides an output current of up to 20A, depending on the external NMOS transistors.
Oscillator frequency is adjustable over a range of 250 kHz to 1 MHz through the use of an external resistor and can be synchronised with an external clock when multiple DC/DC converters are used in the power supply. Phase compensation can also be adapted through an external resistor and capacitor. To improve efficiency under light-load conditions, the R1272S is able to switch automatically from PWM (pulse-width modulation) mode to VFM (variable-frequency modulation) mode, although it can be set in a fixed PWM mode.
Embedded safety circuits include current limit, hiccup-mode or latch-type overcurrent protection, thermal shutdown, and undervoltage lockout. The R1272S also provides a soft-start circuit, low inductor-current shutdown, a flag output of the output-voltage status, spread-spectrum clock generation for EMI reduction, and an external startup tracking-voltage function.
Ricoh Electronic Devices; www.e-devices.ricoh.co.jp/en
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