ST1S09
2 A, 1.5 MHz PWM step-down switching regulator
with synchronous rectification
Features
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1.5 MHz fixed frequency PWM with current
control mode
2 A output current capability
Typical efficiency: > 90%
2 % DC output voltage tolerance
Two versions available: power good or inhibit
Integrated output over-voltage protection
Non switching quiescent current: (typ) 1.5 mA
over temperature range
R
DSON
(typ) 100 mΩ
Utilizes tiny capacitors and inductors
Operating junction temp. -30 °C to 125 °C
Available in DFN6 (3x3 mm) exposed pad
Moreover, since the required synchronous
rectifier is integrated, the number of the external
components is reduced to minimum: a resistor
divider, an inductor and two capacitors. The
power good function continuously monitors the
output voltage. An open drain power good flag is
released when the output voltage is within
regulation. In addition, a low output ripple is
guaranteed by the current mode PWM topology
and by the use of low E.S.R. SMD ceramic
capacitors. The device is thermally protected and
the output current limited to prevent damages due
to accidental short circuit. The ST1S09 is
available in the DFN6 3x3 mm package.
DFN6 (3x3mm)
Description
The ST1S09 is a step-down DC-DC converter
optimized for powering low output voltage
applications. It supplies a current in excess of 2 A
over an input voltage range from 2.7 V to 6 V.
A high PWM switching frequency (1.5 MHz)
allows the use of tiny surface-mount components.
Table 1.
Device summary
Order codes
ST1S09PU
ST1S09APU
(1)
ST1S09IPU
Packaging
ST1S09PUR
ST1S09APUR
ST1S09IPUR
Package
DFN6D (3x3 mm)
DFN6D (3x3 mm)
DFN6D (3x3 mm)
1. Available on request.
January 2008
Rev 3
1/18
www.st.com
18
ST1S09
Contents
1
2
3
4
5
6
7
8
9
Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2/18
ST1S09
Maximum ratings
3
Table 3.
Maximum ratings
Absolute maximum ratings
Parameter
Positive power supply voltage
Positive power supply voltage
Inhibit voltage (I version)
Max. voltage of output pin
Feedback voltage
Power Good open drain
Max junction temperature
Storage temperature range
Lead temperature (soldering) 10 sec
Value
-0.3 to 7
-0.3 to 7
-0.3 to V
I
+ 0.3
-0.3 to 7
-0.3 to 3
-0.3 to 7
-40 to 150
-65 to 150
260
Unit
V
V
V
V
V
V
°C
°C
°C
Symbol
V
IN_SW
V
IN_A
V
INH
SWITCH Voltage
V
FB
PG
T
J
T
STG
T
LEAD
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Thermal data
Parameter
Thermal resistance junction-case
Thermal resistance junction-ambient
Value
10
55
Unit
°C/W
°C/W
Table 4.
Symbol
R
thJC
R
thJA
Table 5.
Symbol
ESD
ESD
ESD performance
Parameter
ESD protection voltage
ESD protection voltage
HBM
MM
Test conditions
Value
2
500
Unit
KV
V
5/18
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