AN2903 Datasheet: Application Note





AN2903 Application Note Datasheet

Part Number AN2903
Description Application Note
Manufacture STMicroelectronics
Total Page 6 Pages
PDF Download Download AN2903 Datasheet PDF

Features: AN2093 APPLICATION NOTE ST1S03 BUCK CONV ERTERS FOR HDD POWER SUPPLIES 1. ABSTRA CT The ST1S03 is a step down DC-DC conv erter optimized for powering the low-vo ltage digital core in HDD applications and, generally, replacing the high curr ent linear solution when the power diss ipation may cause excessive heating of the application environment. It provide s up to 1.5A over an input voltage rang e of 3V to 16V. A high switching freque ncy (1.5MHz) allows the use of tiny sur face-mount components, as well as the u se of a resistor divider to set the out put voltage value. Only an inductor, a Schottky diode and two capacitors are r equired. Besides, a low output ripple i s guaranteed by the current mode PWM ww w.DataSheet4U.com topology and by the u se of low E.S.R. SMD ceramic capacitors . The device is thermal protected and c urrent limited to prevent damages due t o accidental short circuit. The ST1S03 is available in DFN6 (3x3) package. Fig ure 1: Assembled Board 2. INTRODUCTION Purpose of this applica.

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AN2093
APPLICATION NOTE
ST1S03
BUCK CONVERTERS FOR HDD POWER SUPPLIES
1. ABSTRACT
The ST1S03 is a step down DC-DC converter optimized for powering the low-voltage digital core in HDD
applications and, generally, replacing the high current linear solution when the power dissipation may
cause excessive heating of the application environment. It provides up to 1.5A over an input voltage range
of 3V to 16V. A high switching frequency (1.5MHz) allows the use of tiny surface-mount components, as
well as the use of a resistor divider to set the output voltage value. Only an inductor, a Schottky diode and
www.DataShettwoepoto4lcUoag.pcyaoacmintodrsbyartehereuqsueiroefd.loBweEsi.dSe.Rs,.
a low
SMD
output ripple is guaranteed by
ceramic capacitors. The device
the current mode PWM
is thermal protected and
current limited to prevent damages due to accidental short circuit. The ST1S03 is available in DFN6 (3x3)
package.
Figure 1: Assembled Board
2. INTRODUCTION
Purpose of this application note is to provide a brief summary of the specifications and the functionality of
the application board.
The ST1S03 is an adjustable current mode PWM step-down DC/DC converter with internal 1.5A power
switch.
It is a complete 1.5A switching regulator with an internal compensation that eliminates additional
components.
The constant frequency, current mode, PWM architecture and stable operation with ceramic capacitors
results in a low, predictable output ripple. In order to maintain the regulation with light load, the device
starts to work in pulse skipping. In a typical application where the input voltage is 5V and Vout is 1.2V, the
device goes in pulse skipping for Iout lower than 15mA.
December 2004
Rev. 2
1/6

                 






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