ST1S12XX ST1S12XX12, ST1S12XX18 Synchronous rectification with enable, 0.7 A, 1.7 MHz fixed or adjustable step-down switching regulator in TSOT23-5L Features Step-down current mode PWM (1.7 MHz) DC- DC converter 3% DC output voltage tolerance Synchronous rectification Fixed output voltage 1.2 V, 1.8 V, and ADJ (available on request 1.5 V, 2.5 V and 3.3 V) TSOT23-5L Enable function Internal soft start Typical efficiency: > 90% 0.7 A output current capability guaranteed by the current mode PWM topology Not switching quiescent current: max 650 A and by the use of low ESR SMD ceramic over temperature range capacitors. The device is thermally protected and the current is limited to prevent damage due to R typ. 250 m and 400 m DSON accidental short-circuit. The ST1S12 is available Uses tiny capacitors and inductors in the TSOT23-5L package. Operative junction temp. -40 C to 125 C Available in TSOT23-5L package Description The ST1S12 is a step down DC-DC converter optimized for powering low-voltage digital cores in HDD applications and, generally, to replace the high current linear solution when the 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 (1.7 MHz) allows the use of tiny surface-mount components. In addition to the resistor divider to set the output voltage value, only an inductor and two capacitors are required. Moreover, a low output ripple is Table 1. Device summary Part numbers Order codes Package ST1S12XX ST1S12GR TSOT23-5L ST1S12XX12 ST1S12G12R TSOT23-5L ST1S12XX18 ST1S12G18R TSOT23-5L February 2012 Doc ID 14314 Rev 5 1/20 www.st.com 20Contents ST1S12XX, ST1S12XX12, ST1S12XX18 Contents 1 Schematic . 3 2 Pin configuration . 4 3 Maximum ratings 5 4 Electrical characteristics . 6 5 Typical application 9 6 Application notes 10 7 Typical performance characteristics . 11 8 Package mechanical data 15 9 Revision history . 19 2/20 Doc ID 14314 Rev 5