May 2009 Doc ID 12236 Rev 9 1/20
20
ST1S06xx
Synchronous rectification with inhibit, 1.5 A, 1.5 MHz fixed or
adjustable, step-down switching regulator
Features
■Step-down current mode PWM (1.5 MHz) DC-
DC converter
■2% DC output voltage tolerance
■Synchronous rectification
■Inhibit function
■Internal soft start
■Typical efficiency: > 90 %
■1.5 A output current capability
■Not switching quiescent current: max 1.5 mA
over temperature range
■RDS(ON) typ.150 mΩ
■Uses tiny capacitors and inductors
■Operative junction temp. - 30 °C to 125 °C
■Available in DFN6D (3x3 mm) exposed pad
Description
The ST1S06xx is a step down DC-DC converter
optimized for powering low-voltage digital core in
HDD applications and, generally, to replace the
high current linear solution when the power
dissipation may cause an high heating of the
application environment. It provides up to 1.5 A
over an input voltage range of 2.7 V to 6 V. An high
switching frequency (1.5 MHz) allows the use of
tiny surface-mount components: as well as the
resistor divider to set the output voltage value,
only an inductor and two capacitors are required.
Besides, 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
thermal protected and current limited to prevent
damages due to accidental short circuit. The
ST1S06xx is available in DFN6D (3x3 mm)
package.
DFN6D (3x3 mm)
Table 1. Device summary
Part numbers Marking Order codes Package
ST1S06 ST1S06 ST1S06PUR DFN6D (3 x 3 mm)
ST1S06A ST1S06A ST1S06APUR DFN6D (3 x 3 mm)
ST1S06XX12 1S0612 ST1S06PU12R DFN6D (3 x 3 mm)
ST1S06XX33 1S0633 ST1S06PU33R DFN6D (3 x 3 mm)
www.st.com
Contents ST1S06xx
2/20 Doc ID 12236 Rev 9
Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ST1S06xx Diagram
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1 Diagram
Figure 1. Schematic diagram
Pin configuration ST1S06xx
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2 Pin configuration
* Pin 1 is VFB for ADJ version and VO for Fixed version
Figure 2. Pin configuration (top view)
ST1S06 ST1S06A
Table 2. Pin description
Pin n° Symbol Note
1FB/V
OFeedback voltage / output voltage
2 GND System ground
3 SW Switching pin
4V
IN_SW Power supply for the mosfet switch
5V
IN_A Power supply for analogic circuit
6V
INH Inhibit pin to turn off the device
Exposed pad to be connected to GND
ST1S06xx Maximum ratings
Doc ID 12236 Rev 9 5/20
3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
VIN_SW Positive power supply voltage -0.3 to 7 V
VIN_A Positive power supply voltage -0.3 to 7 V
VINH Inhibit voltage -0.3 to VI + 0.3 V
SWITCH
voltage Max. voltage of output pin -0.3 to 7 V
VFB/VOFeedback voltage -0.3 to 2.5 V
VOOutput voltage (for VO > 1.6 V) -0.3 to 6 V
TJMax junction temperature -40 to 150 °C
TSTG Storage temperature range -65 to 150 °C
TLEAD Lead temperature (soldering) 10 sec 260 °C
Table 4. Thermal data
Symbol Parameter Value Unit
RthJA Thermal resistance junction-ambient 55 °C/W
RthJC Thermal resistance junction-case 10 °C/W
Electrical characteristics ST1S06xx
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4 Electrical characteristics
VIN_SW = VIN_A = VINH = 5 V, VO = 1.2 V, CI = 4.7 µF, CO = 22 µF, L1 = 3.3 µH, TJ = -30 °C to
125 °C unless otherwise specified. Typical values are referred to TJ = 25 °C.
Note: 1 Guaranteed by design, but not tested in production
Table 5. Electrical characteristics for ST1S06
Symbol Parameter Test conditions Min. Typ. Max. Unit
FB Feedback voltage 784 800 816 mV
IFB VFB pin bias current 600 nA
VIMinimum input voltage IO = 10mA to 1.5A 2.7 V
IQQuiescent current VINH > 1.2V 1.5 mA
VINH < 0.4V, TJ = -30°C to 85°C 1 µA
IOOutput current VI = 2.7 to 5.5V Note 1 1.5 A
VINH Inhibit threshold
Device ON, VI = 2.7 to 5.5V 1.3
VDevice ON, VI = 2.7 to 5V 1.2
Device OFF 0.4
IINH Inhibit pin current 2µA
%VO/ΔVIReference line regulation VI = 2.7V to 5.5V Note 1 0.2 0.3 %VO/
ΔVI
%VO/ΔIOReference load regulation IO = 10mA to 1.5A Note 1 0.2 0.3 %VO/
ΔIO
PWMfSPWM switching frequency VFB = 0.8V 1.2 1.5 1.8 MHz
DMAX Maximum duty cycle 80 87 %
RDSON-N NMOS switch on resistance ISW = 750 mA 0.12 Ω
RDSON-P PMOS switch on resistance ISW = 750 mA 0.15 Ω
ISWL Switching current limitation Note 1 2.3 A
νEfficiency Note 1 IO = 10mA to 100mA, VO = 3.3V 65 %
IO = 100mA to 1.5A, VO = 3.3V 85 90
TSHDN Thermal shutdown 130 150 °C
THYS Thermal shutdown hysteresis 15 °C
%VO/ΔIOLoad transient response IO = 100mA to 750mA, TJ =
25°C tR = tF ≥ 200ns, Note 1 -5 +5 %VO
%VO/ΔIOShort circuit removal response IO = 10mA to IO = short,
TJ = 25°C Note 1 -10 +10 %VO
ST1S06xx Electrical characteristics
Doc ID 12236 Rev 9 7/20
VIN_SW = VIN_A = VINH = 5 V, VO = 1.2 V, CI = 4.7 µF, CO = 22 µF, L1 = 3.3 µH, TJ = -30 °C to
125 °C unless otherwise specified. Typical values are referred to TJ = 25 °C.
Note: 1 Guaranteed by design, but not tested in production
Table 6. Electrical characteristics for ST1S06PM12
Symbol Parameter Test conditions Min. Typ. Max. Unit
OUT Output feedback pin 1.176 1.2 1.224 V
IOIO pin bias current VO = 1.5V 15 20 µA
VIMinimum input voltage IO = 10mA to 1.5A 2.7 V
IQQuiescent current VINH > 1.2V 1.5 mA
VINH < 0.4V, TJ = -30°C to 85°C 1 µA
IOOutput current VI = 2.7 to 5.5V Note 1 1.5 A
VINH Inhibit threshold
Device ON, VI = 2.7 to 5.5V 1.3
VDevice ON, VI = 2.7 to 5V 1.2
Device OFF 0.4
IINH Inhibit pin current 2µA
%VO/ΔVIReference line regulation VI = 2.7V to 5.5V Note 1 0.2 0.3 %VO/
ΔVI
%VO/ΔIOReference load regulation IO = 10mA to 1.5A Note 1 0.2 0.3 %VO/
ΔIO
PWMfSPWM switching frequency VFB = 0.8V 1.2 1.5 1.8 MHz
DMAX Maximum duty cycle 80 87 %
RDSON-N NMOS switch on resistance ISW = 750 mA 0.12 Ω
RDSON-P PMOS switch on resistance ISW = 750 mA 0.15 Ω
ISWL Switching current limitation Note 1 2.3 A
νEfficiency Note 1 IO = 10mA to 100mA, VO = 1.2V 60 %
IO = 100mA to 1.5A, VO = 1.2V 80 85
TSHDN Thermal shutdown 130 150 °C
THYS Thermal shutdown hysteresis 15 °C
%VO/ΔIOLoad transient response IO = 100mA to 750mA, TJ =
25°C tR = tF ≥ 200ns, Note 1 -5 +5 %VO
%VO/ΔIOShort circuit removal response IO = 10mA to IO = short,
TJ = 25°C Note 1 -10 +10 %VO
Electrical characteristics ST1S06xx
8/20 Doc ID 12236 Rev 9
VIN_SW = VIN_A = VINH = 5 V, VO = 3.3 V, CI = 4.7 µF, CO = 22 µF, L1 = 3.3 µH, TJ = -30 °C to
125 °C unless otherwise specified. Typical values are referred to TJ = 25 °C.
Note: 1 Guaranteed by design, but not tested in production
Table 7. Electrical characteristics for ST1S06PM33
Symbol Parameter Test conditions Min. Typ. Max. Unit
OUT Output feedback pin 3.23 3.3 3.37 V
IOIO pin bias current VO = 3.5V 15 20 µA
VIMinimum input voltage IO = 10mA to 1.5A 4.2 V
IQQuiescent current VINH > 1.2V 1.5 mA
VINH < 0.4V, TJ = -30°C to 85°C 1 µA
IOOutput current VI = 4.2 to 5.5V Note 1 1.5 A
VINH Inhibit threshold
Device ON, VI = 4.2 to 5.5V 1.3
VDevice ON, VI = 4.2 to 5V 1.2
Device OFF 0.4
IINH Inhibit pin current 2µA
%VO/ΔVIReference line regulation VI = 4.2V to 5.5V Note 1 0.2 0.3 %VO/
ΔVI
%VO/ΔIOReference load regulation IO = 10mA to 1.5A Note 1 0.2 0.3 %VO/
ΔIO
PWMfSPWM switching frequency VFB = 0.8V 1.2 1.5 1.8 MHz
DMAX Maximum duty cycle 80 87 %
RDSON-N NMOS switch on resistance ISW = 750 mA 0.12 Ω
RDSON-P PMOS switch on resistance ISW = 750 mA 0.15 Ω
ISWL Switching current limitation Note 1 2.3 A
νEfficiency Note 1 IO = 10mA to 100mA, VO = 3.3V 65 %
IO = 100mA to 1.5A, VO = 3.3V 85 90
TSHDN Thermal shutdown 130 150 °C
THYS Thermal shutdown hysteresis 15 °C
%VO/ΔIOLoad transient response IO = 100mA to 750mA, TJ =
25°C tR = tF ≥ 200ns, Note 1 -5 +5 %VO
%VO/ΔIOShort circuit removal response IO = 10mA to IO = short,
TJ = 25°C Note 1 -10 +10 %VO
ST1S06xx Typical performance characteristics
Doc ID 12236 Rev 9 9/20
5 Typical performance characteristics
VIN_SW = VIN_A = VINH = 5 V, CI = 4.7 µF, CO = 22 µF, L1 = 3.3 µH, unless otherwise
specified. Typical values are referred to 25 °C.
Figure 3. Efficiency vs. output current Figure 4. Efficiency vs. output current
Figure 5. Efficiency vs. output current Figure 6. Efficiency vs. output current
Figure 7. Efficiency vs. output current Figure 8. Efficiency vs. inductor
Typical performance characteristics ST1S06xx
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Figure 9. Voltage feedback vs. temperature Figure 10. Input voltage vs. output voltage
Figure 11. Feedback pin bias current vs.
temperature
Figure 12. Quiescent current vs. temperature
Figure 13. Quiescent current vs. temperature Figure 14. Inhibit voltage vs. input voltage
ST1S06xx Typical performance characteristics
Doc ID 12236 Rev 9 11/20
Figure 15. Inhibit voltage vs. temperature Figure 16. Inhibit voltage vs. temperature
Figure 17. Line regulation vs. temperature Figure 18. Load regulation vs. temperature
Figure 19. PWM switching frequency vs.
temperature
Figure 20. NMOS switch on resistance vs.
temperature
Typical performance characteristics ST1S06xx
12/20 Doc ID 12236 Rev 9
Figure 21. PMOS switch on resistance vs.
temperature
Figure 22. Inhibit transient
VI = 5 V, VINH = 0 to 2 V, IO = 1.5 A
Figure 23. Inhibit transient
VI = 5 V, VINH = 0 to 2 V, IO = 10 mA
ST1S06xx Typical application
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6 Typical application
Figure 24. Application circuit
Application notes ST1S06xx
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7 Application notes
The ST1S06xx is an adjustable current mode PWM step-down DC-DC converter with
internal 1.5 A power switch, packaged in a 6-lead DFN 3x3.
It’s a complete 1.5 A switching regulator with its internal compensation eliminating additional
component.
The constant frequency, current mode, PWM architecture and stable operation with ceramic
capacitors results in low, predictable output ripple. However, in order to maximize the power
conversion efficiency with light load, the regulator reduces automatically the switching
frequency when the output load becomes less than 250 mA typically.
To clamp the error amplifier reference voltage a soft start control block generating a voltage
ramp, has been implemented. Besides an on-chip power on reset of 50 = 100 µs ensure the
proper operation when switching on the power supply. Other circuits fitted to the device
protection are the thermal shut down block which turn off the regulator when the junction
temperature exceeds 150 °C typically and the cycle-by-cycle current limiting that provides
protection against shorted outputs.
Being the ST1S06xx an adjustable regulator, the output voltage is determined by an
external resistor divider. The desired value is given by the following equation:
VO = VFB [1 + R1 / R2]
To make the device working, only few component are required: an inductor and two
capacitors and the resistor divider. The chosen inductor must be able to not saturate at the
peak current level. Besides, its value can be selected keeping in account that a large
inductor value increases the efficiency at low output current and reduces output voltage
ripple, while a smaller inductor can be chosen when it is important to reduce the package
size and the total cost of the application. Finally, the ST1S06xx has been designed to work
properly with X5R or X7R SMD ceramic capacitors both at the input and at the output. this
kind of capacitors, thanks to their very low series resistance (ESR), minimize the output
voltage ripple. Other low ESR capacitors can be used according to the need of the
application without invalidate the right functioning of the device.
ST1S06xx Package mechanical data
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8 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com. ECOPACK
is an ST trademark.
Package mechanical data ST1S06xx
16/20 Doc ID 12236 Rev 9
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A0.80 1.00 0.031 0.039
A1 0 0.02 0.05 0 0.001 0.002
A30.20 0.008
b0.230.45 0.0090.018
D2.903.00 3.10 0.114 0.1180.122
D2 2.232.50 0.088 0.098
E2.903.00 3.10 0.114 0.1180.122
E2 1.50 1.75 0.0590.069
e0.950.037
L0.30 0.40 0.50 0.012 0.016 0.020
DFN6D (3x3 mm) mechanical data
7946637B
ST1S06xx Package mechanical data
Doc ID 12236 Rev 9 17/20
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A330 12.992
C 12.813.2 0.504 0.519
D 20.2 0.795
N60 2.362
T18.4 0.724
Ao 3.30.130
Bo 3.30.130
Ko 1.1 0.043
Po 4 0.157
P80.315
Tape and reel QFNxx/DFNxx (3x3 mm) mechanical data
Package mechanical data ST1S06xx
18/20 Doc ID 12236 Rev 9
Figure 25. DFN6 (3x3 mm) footprint recommended data
ST1S06xx Revision history
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9 Revision history
Table 8. Document revision history
Date Revision Changes
08-May-2006 1 Initial release.
06-Jun-2006 2 Tab le 3 updated.
16-Oct-2006 3 Add new mechanical data DFN6D.
09-Nov-2006 4 Mechanical data information for DFN6 update.
03-Apr-2007 5 Tape and reel updated.
12-Mar-2008 6 Added: Table 1 on page 1.
15-Apr-2008 7 Modified: Figure 6 on page 9.
10-Apr-2009 8 Modified: Table 3 on page 5.
06-May-2009 9 Added: marking Table 1 on page 1.
ST1S06xx
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