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Tiny dc/dc boost converters

Claimed to be the smallest- available low input voltage devices, the SC120, SC121, and SC122 occupy a 1.5 x 2mm ultra-thin plastic package and step up inputs from as low as 0.7V to a regulated output settable from 1.8V to 5.0V. You can use them in portable applications powered by alkaline, NiMH, or 1-cell Li-ion batteries, or as point-of-load regulators in non-portable applications where a low voltage needs to be boosted to a higher voltage rail for localised use. The SC120 has 1.2MHz low-noise PWM operation, an internal low-on-resistance switch and synchronous rectifier for up to 94% efficiency, automatic PSAVE mode for light-load efficiency, an anti-ringing circuit that dampens stray oscillations on the inductor terminal, ±1.5% initial accuracy, internal/external feedback modes, soft-start, thermal and current limit protection, and a 0.1-μA real shutdown mode that reverses the rectifier’s body-diode and actively discharges the output fully to ground. For highly noise-sensitive applications, the SC121 eliminates the PSAVE mode in favour of forced-PWM operation at all loads. For specialised keep-alive applications, the SC122 uses PSAVE mode only and allows the output voltage to float high during shutdown by eliminating active discharge. The SC122 also limits the input to no more than 1.6V and the output to a fixed 3.3V. The chips cost from $0.80 each (3000).

Semtech, www.semtech.com/power-management/switching-regulators/