ST1S10

Manufacturer Part NumberST1S10
DescriptionMonolithic synchronous step-down regulator
ManufacturerSTMicroelectronics
ST1S10 datasheet
 


Specifications of ST1S10

Input Voltage Range2.5 V to 18 VMax Iout3 A
High Internal Switching Frequency900 kHzQuiescent Current< 6 μA in inhibit state
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Features
Step-down current mode PWM regulator
Output voltage adjustable from 0.8 V
Input voltage from 2.5 V up to 18 V
2% DC output voltage tolerance
Synchronous rectification
Inhibit function
Synchronizable switching frequency from 400
kHz up to 1.2 MHz
Internal soft start
Dynamic short circuit protection
Typical efficiency: 90%
3 A output current capability
Stand-by supply current: max 6 µA over
temperature range
Operative junction temp: from - 25 °C to 125 °C
Applications
Consumer
– STB, DVD, DVD recorders, TV, VCR, car
audio, LCD monitors
Networking
– XDSL, modems, DC-DC modules
Computer
– Optical storage, HD drivers, printers,
audio/graphic cards
Industrial and security
– Battery chargers, DC-DC converters, PLD,
PLA, FPGA, LED drivers
Table 1.
Device summary
Part number
ST1S10
March 2011
3 A, 900 kHz, monolithic synchronous
step-down regulator IC
DFN8 (4 x 4 mm)
Description
The ST1S10 is a high efficiency step-down PWM
current mode switching regulator capable of
providing up to 3 A of output current. The device
operates with an input supply range from 2.5 V to
18 V and provides an adjustable output voltage
from 0.8 V (V
) to 0.85*V
FB
R1 / R2)]. It operates either at a 900 kHz fixed
frequency or can be synchronized to an external
clock (from 400 kHz to 1.2 MHz). The high
switching frequency allows the use of tiny SMD
external components, while the integrated
synchronous rectifier eliminates the need for a
Schottky diode. The ST1S10 provides excellent
transient response, and is fully protected against
thermal overheating, switching over-current and
output short circuit. The ST1S10 is the ideal
choice for point-of-load regulators or LDO pre-
regulation.
Order codes
DFN8 (4 x 4 mm)
ST1S10PUR
Doc ID 13844 Rev 4
ST1S10
PowerSO-8
[V
= V
*(1 +
IN_SW
OUT
FB
PowerSO-8
ST1S10PHR
1/26
www.st.com
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ST1S10 Summary of contents

  • Page 1

    ... A, 900 kHz, monolithic synchronous step-down regulator IC DFN8 ( mm) Description The ST1S10 is a high efficiency step-down PWM current mode switching regulator capable of providing output current. The device operates with an input supply range from 2 and provides an adjustable output voltage from 0 ...

  • Page 2

    ... Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2/26 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 > 2 OUT < 2 OUT > 2 OUT < 2 OUT Sync operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Inhibit function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 OCP (over-current protection SCP (short circuit protection SCP and OCP operation with high capacitive load . . . . . . . . . . . . . . . . 12 Doc ID 13844 Rev 4 ST1S10 ...

  • Page 3

    ... Typical application circuit 12V 12V VIN_SW VIN_SW 4.7µF 4.7µF VIN_A VIN_A C3 C3 0.1µF 0.1µ ST1S10 ST1S10 FB FB SYNC SYNC AGND AGND PGND PGND Doc ID 13844 Rev 4 Application circuit L1 L1 3.3µH 3.3µH 5V – – – 22µ ...

  • Page 4

    ... Power input supply voltage to be tied to V Switching node to be connected to the inductor Power ground Exposed pad to be connected to ground Doc ID 13844 Rev 4 PowerSO-8 supply source IN if not used IN_A Section 5.5: Output voltage selection) Section 5.8.1: power supply source IN ST1S10 OUT ...

  • Page 5

    ... ST1S10 3 Maximum ratings Table 3. Absolute maximum ratings Symbol V Positive power supply voltage IN_SW V Positive supply voltage IN_A V Inhibit voltage INH V Output switch voltage SW V Feedback voltage current FB Sync Synchronization T Storage temperature range STG T Operating junction temperature range OP Note: Absolute maximum ratings are the values beyond which damage to the device may occur. ...

  • Page 6

    ... Max. 784 800 816 776 800 824 600 1.5 2 3.0 (2) 1.2 0.4 2 0.4 0.5 0.7 0.9 1 0.10 0.12 5 150 15 < ±5 ±10 0.4 1.2 250 0.4 1.6 ST1S10 = 4.7 µF IN Unit µ µ OUT Δ OUT ΔI OUT MHz % Ω Ω °C ° MHz ...

  • Page 7

    ... ST1S10 Table 5. Electrical characteristics (continued) Symbol Parameter I I SYNC input current IL, IH UVLO Under voltage lock-out threshold 1. Guaranteed by design, but not tested in production. 2. See output voltage selection paragraph 5.5 for maximum duty cycle conditions. Test conditions SYNC ...

  • Page 8

    ... SYNC pin. The current mode PWM architecture and stable operation with low ESR SMD ceramic capacitors results in low, predictable output ripple. No external compensation is needed. To maximize power conversion efficiency, the ST1S10 works in pulse skipping mode at light load conditions and automatically switches to PWM mode when the output current increases. ...

  • Page 9

    ... ST1S10 Equation OUT F where V is the voltage drop across the internal NMOS, and V F drop across the internal PDMOS. The minimum duty cycle (at V duty cycle (at V IN_min through the input capacitor. A minimum value of 4.7 µF for the V suitable in most application conditions µF or higher ceramic capacitor for the V and a 1 µ ...

  • Page 10

    ... The ST1S10 has been designed to perform best with ceramic capacitors. Under typical application conditions a minimum ceramic capacitor value of 22 µF is recommended on the output, but higher values are suitable considering that the control loop has been designed to work properly with a natural output LC frequency provided by a 3.3 µ ...

  • Page 11

    ... Sync operation The ST1S10 operates at a fixed frequency or can be synchronized to an external frequency with the SYNC pin. The ST1S10 switches at a frequency of 900 kHz when the SYNC pin is connected to ground, and can synchronize the switching frequency between 400 kHz to 1.2 MHz from an external clock applied to the SYNC pin. When the SYNC feature is not used, this pin must be connected to ground with a path as short as possible to avoid any possible noise injected in the SYNC internal circuitry ...

  • Page 12

    ... Any slew rate can be used to drive the inhibit pin. 5.8.3 OCP (over-current protection) The ST1S10 DC-DC converter is equipped with a switch over-current protection. In order to provide protection for the application and the internal power switches and bonding wires, the device goes into a shutdown state if the switch current limit is reached and is kept in this ...

  • Page 13

    ... ST1S10 ST1S10 FB FB SYNC SYNC AGND AGND PGND PGND ST1S10 ST1S10 EN EN SYNC SYNC AGND AGND PGND PGND ST1S10 ST1S10 EN EN SYNC SYNC AGND AGND PGND PGND Doc ID 13844 Rev 4 Application information L1 L1 3.3µH 3.3µH C4 (*) C4 (*) 5V – – – ...

  • Page 14

    ... Layout considerations Layout is an important step in design for all switching power supplies. High-speed operation (900 kHz) of the ST1S10 device demands careful attention to PCB layout. Care must be taken in board layout to get device performance, otherwise the regulator could show poor line and load regulation, stability issues as well as EMI problems. ...

  • Page 15

    ... Thermal considerations The lead frame die pad, of ST1S10, is exposed at the bottom of the package and must be soldered directly to a properly designed thermal pad on the PCB, the addition of thermal vias from the thermal pad to an internal ground plane will help increase power dissipation. ...

  • Page 16

    ... Diagram 7 Diagram Figure 8. Block diagram 16/26 Doc ID 13844 Rev 4 ST1S10 ...

  • Page 17

    ... ST1S10 8 Typical performance characteristics Unless otherwise specified, refer to the typical application circuit under the following conditions 25° mA, C OUT IN Figure 9. Voltage feedback vs. temperature 830 830 830 820 820 820 810 810 810 800 800 800 790 790 790 ...

  • Page 18

    ... -25 - TEMPERATURE [°C] TEMPERATURE [° =12V, V =12V, V =5V, T =5V, T =25°C =25°C IN-A IN-A IN-SW IN-SW INH INH OUT OUT J J 0.5 0 1.5 1 OUTPUT CURRENT [A] OUTPUT CURRENT [A] ST1S10 100 100 125 125 100 100 125 125 2.5 2 ...

  • Page 19

    ... ST1S10 Figure 21. Efficiency vs. output current 100 100 =5V, V =5V, V IN-A IN-A IN-SW IN-SW INH INH 0.5 0 1.5 1.5 OUTPUT CURRENT [A] OUTPUT CURRENT [A] Figure 22. Efficiency vs. output current 100 100 =3.3V, T =3.3V, T =25°C =25°C OUT OUT ...

  • Page 20

    ... Package mechanical data 9 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 trademark. 20/26 Doc ID 13844 Rev 4 ST1S10 ® ...

  • Page 21

    ... ST1S10 PowerSO-8 (exposed pad) mechanical data Dim ccc mm. Min. Typ. 0.00 1.25 0.31 0.17 4.80 4.90 ACCORDING TO PAD SIZE 5.80 6.00 3.80 3.90 ACCORDING TO PAD SIZE 1.27 0.25 0.40 0° Doc ID 13844 Rev 4 Package mechanical data Max. 1.70 0.15 0.51 0.25 5.00 6.20 4.00 0.50 1.27 8° 0.10 7195016C 21/26 ...

  • Page 22

    ... L 0.40 22/26 DFN8 (4x4) mechanical data mm. Typ. Max. 0.90 1.00 0.02 0.05 0.20 0.30 0.38 4.00 4.10 3.00 3.23 4.00 4.10 2.20 2.30 0.80 0.50 0.60 Doc ID 13844 Rev 4 inch. Min. Typ. 0.031 0.035 0 0.001 0.008 0.009 0.012 0.154 0.157 0.111 0.118 0.154 0.157 0.081 0.087 0.031 0.016 0.020 7869653B ST1S10 Max. 0.039 0.002 0.015 0.161 0.127 0.161 0.091 0.024 ...

  • Page 23

    ... ST1S10 Dim. Min 12 8.1 Bo 5.5 Ko 2.1 Po 3.9 P 7.9 Tape & reel SO-8 mechanical data mm. Typ. Max. 330 13.2 22.4 8.5 5.9 2.3 4.1 8.1 Doc ID 13844 Rev 4 Package mechanical data inch. Min. Typ. 12.992 0.504 0.795 2.362 0.319 0.216 0.082 0.153 0.311 Max. 0.519 0.882 0.335 0.232 0.090 0.161 ...

  • Page 24

    ... Package mechanical data Tape & reel QFNxx/DFNxx (4x4) mechanical data Dim. Min 12 24/26 mm. Typ. Max. Min. 330 13.2 0.504 0.795 101 3.898 14.4 4.35 4.35 1 Doc ID 13844 Rev 4 ST1S10 inch. Typ. Max. 12.992 0.519 3.976 0.567 0.171 0.171 0.043 0.157 0.315 ...

  • Page 25

    ... ST1S10 10 Revision history Table 6. Document revision history Date Revision 28-Aug-2007 1 24-Sep-2007 2 25-Oct-2007 3 10-Mar-2011 4 Initial release. Add R on Table 4. thJC Added new paragraph 6: Layout considerations. Updated PowerSO-8 package mechanical data and Doc ID 13844 Rev 4 Revision history Changes Figure 6 on page 14. 25/26 ...

  • Page 26

    ... Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America 26/26 Please Read Carefully: © 2011 STMicroelectronics - All rights reserved STMicroelectronics group of companies www.st.com Doc ID 13844 Rev 4 ST1S10 ...