Description
This demonstration board is based on the ST1S12 family of synchronous step-down DC-DC converters optimized for powering low-voltage digital cores in HDD (hard disk drive) applications and is generally used to replace high-current linear solutions when power dissipation may cause high heating of the application environment. It provides up to 0.7 A over an input voltage range of 2.5 V to 5.5 V. A high switching frequency of 1.7 MHz allows the use of tiny surface-mount components. For the adjustable version, a resistor divider to set the output voltage value, an inductor, and two capacitors are required. Only an inductor and 2 capacitors are needed for the 1.2 V and 1.8 V fixed version. A low output ripple is guaranteed by the current mode PWM topology and by the use of low ESR surface-mount ceramic capacitors. The ST1S12 device is thermal protected and current limited to prevent damage due to accidental short-circuit. This family of products is available in the TSOT23-5L package. STEVAL-ISA055V1

Features
■ Step-down current mode PWM (1.7 MHz) DC- DC converter
■ Fixed output voltage of 1.2 V
■ 0.7 A output current capability
■ 3% DC output voltage tolerance
■ Synchronous rectification
■ Enable function
■ Internal soft-start
■ Typical efficiency: > 90%
■ Not switching quiescent current: max 600 µA over temperature range
■ RDS(on) typ. 250 mΩ and 400 mΩ
■ Uses tiny capacitors and inductors