June 2008 Rev 6 1/14
14
ST1S03A
1.5 A, 1.5 MHz adjustable, with inhibit function
step-down switching regulator
Features
■ Step-down current mode PWM (1.5 MHz) DC-
DC converter
■ 2 % DC output voltage tolerance
■ Internal soft start for start-up current limitation
and power on delay of 50-100 µs
■ Typical efficiency: > 85 %
■ Inhibit function
■ 1.5 A output current capability
■ Not switching quiescent current: max 1.5 mA
over temperature range
■ Switch V
DS
: max 200 mV @ I
SW
= 750 mA
■ Uses tiny capacitors and inductors
■ Available in DFN6D 3x3 exposed pad
Description
The ST1S03A is a step down DC-DC converter
optimized for powering low-voltage digital core in
HDD applications and, generally, to replace the
high current linear solution when the power
dissipation may cause an high heating of the
application environment. It provides up to 1.5 A
over an input voltage range of 3 V to 5.5 V. An high
switching frequency (1.5 MHz) allows the use of
tiny surface-mount components: as well as the
resistor divider to set the output voltage value,
only an inductor, a schottky diode and two
capacitors are required. Besides, a low output
ripple is guaranteed by the current mode PWM
topology and by the use of low ESR SMD ceramic
capacitors. The device is thermal protected and
current limited to prevent damages due to
accidental short circuit. The ST1S03A is available
in DFN6D (3x3 mm).
Table 1. Device summary
Order codes Packaging Package
ST1S03APUR Tape and reel DFN6D (3x3 mm)
ST1S03AIPUR Tape and reel DFN6D (3x3 mm)
www.st.com
DFN6D (3x3 mm)
