ST1S12XX
ST1S12XX12, ST1S12XX18
Synchronous rectification with enable, 0.7 A, 1.7 MHz fixed or
adjustable step-down switching regulator in TSOT23-5L
Features
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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 600 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
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 ST1S12Gxx is
available in the TSOT23-5L package.
TSOT23-5L
Description
The ST1S12Gxx 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
Table 1.
Device summary
Part numbers
ST1S12XX
ST1S12XX12
ST1S12XX18
Order codes
ST1S12GR
ST1S12G12R
ST1S12G18R
Package
TSOT23-5L
TSOT23-5L
TSOT23-5L
February 2010
Doc ID 14314 Rev 3
1/20
www.st.com
20
Contents
ST1S12XX, ST1S12XX12, ST1S12XX18
Contents
1
2
3
4
5
6
7
8
9
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2/20
Doc ID 14314 Rev 3
ST1S12XX, ST1S12XX12, ST1S12XX18
Maximum ratings
3
Table 3.
Maximum ratings
Absolute maximum ratings
Parameter
Positive power supply voltage
Enable voltage
Max. voltage of output pin
Feedback voltage
Output voltage (for V
O
> 1.6 V)
Max junction temperature
Storage temperature range
Lead temperature (soldering) 10 sec
Value
-0.3 to 6.5
-0.3 to V
IN
+ 0.3
-0.3 to V
IN
+ 0.3
-0.3 to 3
-0.3 to 6
-40 to 150
-65 to 150
260
Unit
V
V
V
V
V
°C
°C
°C
Symbol
V
IN
V
EN
SWITCH Voltage
V
FB
/V
O
V
O
T
J
T
STG
T
LEAD
Note:
Absolute maximum ratings are the values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Thermal data
Parameter
Thermal resistance junction-ambient
Thermal resistance junction-case
Value
220
110
Unit
°C/W
°C/W
Table 4.
Symbol
R
thJA
R
thJC
Table 5.
Symbol
ESD
ESD performance
Parameter
ESD protection voltage
MM
0.3
kV
Test conditions
HBM
Value
2
Unit
kV
Doc ID 14314 Rev 3
5/20