February 2012 Doc ID 14314 Rev 5 1/20
20
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)
■ Enable function
■ Internal soft start
■ Typical efficiency: > 90%
■ 0.7 A output current capability
■ Not switching quiescent current: max 650 µA
over temperature range
■ R
DSON
typ. 250 mΩ and 400 mΩ
■ Uses tiny capacitors and inductors
■ 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
guaranteed by the current mode PWM topology
and by the use of low ESR SMD ceramic
capacitors. The device is thermally protected and
the current is limited to prevent damage due to
accidental short-circuit. The ST1S12 is available
in the TSOT23-5L package.
TSOT23-5L
Table 1. Device summary
Part numbers Order codes Package
ST1S12XX ST1S12GR TSOT23-5L
ST1S12XX12 ST1S12G12R TSOT23-5L
ST1S12XX18 ST1S12G18R TSOT23-5L
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