ST ST1S09 User Manual
2 A, 1.5 MHz PWM step-down switching regulator
Features
■ 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
■ Utilizes tiny capacitors and inductors
■ Operating junction temp. -30 °C to 125 °C
■ Available in DFN6 (3 x 3 mm) exposed pad
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.
(typ) 100 mΩ
DSON
ST1S09
with synchronous rectification
DFN6 (3 x 3 mm)
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 ESR 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 (3 x 3 mm) package.
Table 1. Device summary
Order codes Package
ST1S09PUR DFN6D (3 x 3 mm)
ST1S09APUR
ST1S09IPUR DFN6D (3 x 3 mm)
1. Available on request.
April 2010 Doc ID 13632 Rev 4 1/18
(1)
DFN6D (3 x 3 mm)
www.st.com
18
ST1S09
Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2/18 Doc ID 13632 Rev 4
ST1S09 Diagram
1 Diagram
Figure 1. Schematic diagram
(*) Only for ST1S09IPU
(**) Only for ST1S09PU
Doc ID 13632 Rev 4 3/18
Pin configuration ST1S09
2 Pin configuration
Figure 2. Pin connections (top view)
ST1S09
ST1S09A
Table 2. Pin description
Pin n° Symbol Name and function
1 FB Feedback voltage
2 GND System ground
3 SW Switching pin
4V
5V
6 INH/PG/NC Inhibit (to turn off the device) / Power Good / Not Connected
Exposed
Pad
IN_SW
IN_A
GND
Power supply for the MOSFET switch
Power supply for analog circuit
To be connected to PCB ground plane for optimal electrical and thermal
performance
ST1S09I
4/18 Doc ID 13632 Rev 4
ST1S09 Maximum ratings
3 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
V
IN_SW
V
V
IN_A
INH
Positive power supply voltage -0.3 to 7 V
Positive power supply voltage -0.3 to 7 V
Inhibit voltage (I version) -0.3 to VI + 0.3 V
SWITCH Voltage Max. voltage of output pin -0.3 to 7 V
V
FB
Feedback voltage -0.3 to 3 V
PG Power Good open drain -0.3 to 7 V
T
T
T
J
STG
LEAD
Max junction temperature -40 to 150 °C
Storage temperature range -65 to 150 °C
Lead temperature (soldering) 10 sec 260 °C
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 4. Thermal data
Symbol Parameter Value Unit
R
thJC
R
thJA
Thermal resistance junction-case 10 °C/W
Thermal resistance junction-ambient 55 °C/W
Table 5. ESD performance
Symbol Parameter Test conditions Value Unit
ESD ESD protection voltage HBM 2 kV
ESD ESD protection voltage MM 500 V
Doc ID 13632 Rev 4 5/18
Electrical characteristics ST1S09
4 Electrical characteristics
Refer to Figure 21 application circuit V
C
= 22 µF, L1 = 2.7 µH, TJ = -30 to 125 °C (unless otherwise specified. Typical values are
2
IN_SW
= V
= 5 V, VO = 1.2 V, C1 = 4.7 µF,
IN_A
referred to 25 °C)
Table 6. Electrical characteristics for ST1S09PU
Symbol Parameter Test conditions Min. Typ. Max. Unit
FB Feedback voltage 784 800 816 mV
I
FB
V
UV
LO
OVP
I
OVP
I
Q
I
O
%VO/ΔVIOutput line regulation VI = 4.5 V to 5.5 V, IO = 100 mA
%VO/ΔIOOutput load regulation IO = 10 mA to 2 A
PWMf
D
MAX
PG
R
DSON
R
DSON
I
SWL
ν
T
SHDN
T
HYS
%VO/ΔIOLoad transient response
VFB pin bias current 600 nA
Input voltage IO = 10 mA to 2 A 4.5 5.5 V
I
Rising 3.5 3.7 3.9 V
V
Under voltage lock out
threshold
Over voltage protection
threshold
Over voltage protection
hysteresis
I
Hysteresis 150 mV
V
rising 1.05 VO1.1 V
O
falling 5 %
V
O
O
Overvoltage clamping current VO = 1.2 V 300 mA
Quiescent current Not switching 1.5 2.5 mA
Output current VI = 4.5 to 5.5 V
PWM switching frequency VFB = 0.65 V 1.2 1.5 1.8 MHz
S
(1)
(1)
2A
(1)
0.16
0.2 0.6 %
Maximum duty cycle 80 87 %
Power good output threshold 0.92 V
Power good output voltage low I
= 6 mA open drain output 0.4 V
SINK
O
-N NMOS switch on resistance ISW = 750 mA 0.1 Ω
-P PMOS switch on resistance ISW = 750 mA 0.1 Ω
Switching current limitation
Efficiency
(1)
(1)
2.5 2.9 3.5 A
IO = 10 mA to 100 mA, VO = 3.3 V 65
= 100 mA to 2 A, VO = 3.3 V 82 87
I
O
Thermal shutdown 150 °C
Thermal shutdown hysteresis 20 °C
= 100 mA to 1 A, TA = 25 °C
I
O
tR = tF ≥ 200 ns
(1)
-10 +10 %V
%V
ΔV
%
V
/
O
I
V
O
I
= 10 mA to IO = short,
%VO/ΔIOShort circuit removal response
1. Guaranteed by design, but not tested in production.
O
TA = 25 °C
(1)
6/18 Doc ID 13632 Rev 4
-10 +10 %V
O
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