STEVAL-ISA055V2 STMicroelectronics

STEVAL-ISA055V2 0.7 A / 3.3 V synchronous buck converter with enable function based on the ST1S12XX Data Brief Features Step-down current mode PWM (1.7 MHz) DC- DC converter Fixed output voltage 3.3 V 0.7 A output current capability 3% DC output voltage tolerance Synchronous rectification Enable function Internal soft-start Typical efficiency: > 90% Non switching quiescent current: max 600 A over temperature range STEVAL-ISA055V2 R typ. 250 m and 400 m DS(on) Uses tiny capacitors and inductors Description This demonstration board is based on the The ST1S12 device is thermal protected and ST1S12 family of synchronous step-down DC-DC current limited to prevent damage due to converters optimized for powering low-voltage accidental short-circuit. This family of products is digital cores in HDD (hard disk drive) applications, available in the TSOT23-5L package. 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. A resistor divider to set the output voltage value, an inductor, and two capacitors are required for the adjustable version, while 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. September 2008 Rev 1 1/4 For further information contact your local STMicroelectronics sales office. www.st.com 4Schematic diagram STEVAL-ISA055V2 1 Schematic diagram Figure 1. ST1S12 circuit schematic diagram V IN V 4 IN R ST1S12 EN L 3 SW 1 EN V OUT V GND FB 2 5 R1 C IN C OUT R2 GND AM00303 2/4