ST750A Adjustable step-down, current-mode PWM DC-DC converters Features ■ Up to 450mA load currents ■ 200kHz high-frequency current-mode PWM ■ 85% to 96% efficiencies ■ 33mH or 100mH pre-selected inductor value, no component design required ■ 0.8mA quiescent current ■ 0.3µA shutdown supply current ■ Adjustable output voltage ■ Overcurrent, soft-start and undervoltage lockout protection ■ Cycle-by-cycle current limiting ■ Package available: SO-8 SO-8 provides precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±4.5% plus feedback resistor tolerance over line, load, and temperature variations. Description The ST750A is an adjustable output CMOS, stepdown switching regulator. The ST750A accepts inputs between 4V and 11V and delivers 450mA. Typical efficiencies are 85% to 96%. Quiescent supply current is 0.8mA and only 0.3mA in shutdown mode. The output does not exhibit frequency over this specified range. Pulsewidth modulation (PWM) current-mode control Fixed-frequency switching and absence of subharmonic ripple allows easy filtering of output ripple and noise, as well as the use of small external components. This regulators require only a single inductor value to work in most applications, so no inductor design is necessary. Typical applications are: Cellular phones & radios, portable Instruments, Portable Communications Equipment and Computer Peripherals. Order code May 2007 Part number Packaging ST750AC ST750ACDTR Rev. 3 1/14 www.st.com 14 ST750A Contents 1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2/14 ST750A Diagram 1 Diagram Figure 1. Schematic diagram 3/14 Pin configuration ST750A 2 Pin configuration Figure 2. Pin connections (top view) Table 1. Pin description Pin N° Symbol Name and function 1 SHDN Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to VCC for normal operation (ON MODE) 2 REF Reference output voltage: (1.25V): Bypass to GND with a capacitor that does not exceed 47nF 3 SS Soft start: a capacitor between SS and GND provides soft-start and short-circuit protections. 4 CC Compensation capacitor input: externally compensates the outer (voltage) feedback loop. Connect to OUT with 330pF capacitor 5 IC Internal connection: make no external connection to this pin 6 GND 7 LX 8 VCC 4/14 Ground Switch output. Drain of internal P-channel power MOSFET Supply voltage input. Bypass to GND with 1μF ceramic capacitance and large value electrolytic capacitor in parallel. The 1μF capacitor must be as close as possible to the GND and VCC pins ST750A Maximum ratings 3 Maximum ratings Table 2. Absolute maximum ratings Symbol Parameter Value Unit -0.3 to 12 V VCC DC Input voltage VLX Switch pin voltage -0.3 to (VCC + 0.3) V VSHDN Shutdown voltage (SHDN) -0.3 to (VCC + 0.3) V VS,VC Soft start (SS) and compensation capacitor (CC) pins voltage -0.3 to (VCC + 0.3) V 2 A 2.5 mA 344 mW -40 to +150 °C 0 to +70 °C ILX Switching peak current IREF Reference current PTOT Continuous power dissipation at TA=70°C Tstg Storage temperature range Top Operating junction temperature range SO-8 C series Note: Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied Table 3. Thermal data Symbol RthJA Parameter Thermal resistance junction-ambient (1) SO-8 Unit 160 °C/W 1. This value depends from thermal design of PCB on which the device is mounted. 5/14 Typical application 4 Typical application Figure 3. Application circuit 6/14 ST750A ST750A Electrical characteristics 5 Electrical characteristics Table 4. Electrical characteristics (VCC=5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified). Symbol Parameter Test conditions Min. Typ. Unit 11 V 5.25 V VCC Input voltage VO Output voltage VCC = 6 to 11V, IO = 0 to 450mA ΔVO Line regulation VCC = 4 to 11V 0.15 %/V ΔVO Load regulation IO = 0 to 450mA 0.005 %/mA η Power efficiency IO = 300mA 92 % ON Mode 0.8 2.5 mA OFF Mode, SHDN = 0 0.3 100 µA ISUPPLY Supply current VIH SHDN Input high threshold VIL SHDN Input low threshold 4 Max. VLOCK Under voltage lockout Reference voltage ΔVREF Temperature reference drift fOSC RC Switching frequency Compensation pin impedance 0.25 V 1 μA 3 V VCC = 12V, VLX = 0V 2.7 TA = 25°C 0.5 Ω 1 µA LX Leakage current VREF V VCC Falling Shutdown input leakage current ILX = 500mA ILX 5 2 ISHDN RDS(on) LX On resistance 4.75 1.17 1.24 1.31 50 C series 160 200 7500 V ppm/°C 280 KHz Ω 7/14 Typical performance characteristics ST750A 6 Typical performance characteristics Figure 4. (Unless otherwise specified TJ = 25°C) Efficiency vs output current Figure 5. Supply current vs temperature Figure 6. Oscillator frequency vs temp. Figure 7. Oscillator frequency vs input volt. Figure 8. Peak inductor current vs out. curr. Figure 9. Output voltage vs output current 8/14 ST750A Typical performance characteristics Figure 10. Switching waveforms, continuous conduction Figure 11. Switching waveforms, discontinuous conduction VI = 6V to 11V, IO = 300mA VI = 6V to 11V, IO = 300mA Figure 12. Line transient Figure 13. Load transient 9/14 Package mechanical data 7 ST750A Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. 10/14 ST750A Package mechanical data SO-8 MECHANICAL DATA DIM. mm. MIN. TYP inch MAX. MIN. TYP. MAX. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd 8˚ (max.) 0.1 0.04 0016023/C 11/14 Package mechanical data ST750A Tape & Reel SO-8 MECHANICAL DATA mm. inch DIM. MIN. A MAX. MIN. 330 13.2 TYP. MAX. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 12/14 TYP 0.504 22.4 0.519 0.882 Ao 8.1 8.5 0.319 0.335 Bo 5.5 5.9 0.216 0.232 Ko 2.1 2.3 0.082 0.090 Po 3.9 4.1 0.153 0.161 P 7.9 8.1 0.311 0.319 ST750A Revision history 8 Revision history Table 5. Revision history Date Revision 29-May-2007 3 Changes Order code has been updated and the document has been reformatted. 13/14 ST750A Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein. UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZE REPRESENTATIVE OF ST, ST PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS, WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY, DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any liability of ST. ST and the ST logo are trademarks or registered trademarks of ST in various countries. Information in this document supersedes and replaces all information previously supplied. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners. © 2007 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com 14/14