DC/DC controller powers application processors

November 16, 2015 // By Susan Nordyk
Accepting an input voltage from 4 to 34V, the R1272S synchronous step-down DC/DC controller from Ricoh serves as a power supply for core processors in set-top boxes, media players, Internet gateways, and automotive infotainment and navigation systems.

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.

R1272S product page

Ricoh Electronic Devices; www.e-devices.ricoh.co.jp/en