STEVAL-ILL008V1

STEVAL-ILL008V1 LED flashlight evaluation board based on the L6920DA Data Brief Features ■ High efficiency step-up converter ■ Powered from two cell batteries ■ Output voltage Vout = 3.5 V ■ Minimum operating input voltage Vin = 1 V Description STEVAL-ILL008V1 White LEDs are gaining popularity as sources of illumination due to their high efficiency and reliability. Typical forward voltage drop across a white LED is approximately 3.5 V. When these LEDs are powered from a single or two cell batteries, a boost converter is needed to boost the voltage to drive the LEDs. This evaluation board, based on the L6920DA, implements a high efficiency step-up converter which requires very few passive components to perform the conversion from the battery voltage to the selected output voltage or current. Startup is guaranteed at 1 V and the device operates down to 0.6 V. The device has a very low quiescent current of only 10 µA. An internal synchronous rectifier is implemented with a 120 mΩ P-channel MOSFET, replacing the conventional boost diode, to improve efficiency. This also could reduce the cost of the application since no external diode required. March 2008 Rev 1 For further information contact your local STMicroelectronics sales office. 1/4 www.st.com 4 2/4 1 1 CON1 J6 CON1 1 SW1 SPDT SW SLIDE-SP Apem 25136N 5136NH 32 BT1 3V + C2 47uF 47u 6.3V 1 12 1 10uH 10u DO1 08C-103 DO1608C-10 Coilcraf Coi craft L1 51 51k 1/8W 5% R5 C4 1uF 0.1u 2 7 4 2 5 OUT LBO L6920D L6920 REF GND LBI SHD HDN FB LX U1 8 6 3 1 + 3 2 1 Vcc U2 5 1 30k 1/8W 5% R3 1nF 1n C5 2 4 Non onInvInv_In 23-5L TS951ILT_SOT23 Vdd Out C1 7uF 47u 6.3V 6TPB47M PB47M S Sany nyo R4 1k 1/8W 5% C3 0.1u 1uF R1 0.33 1/8W 1% 1 1 J5 CON1 J4 CON1 D1 LED Figure 1. 2 1 1 2 1 J2 Circuit schematic STEVAL-ILL008V1 Circuit schematic Schematic STEVAL-ILL008V1 2 Revision history Revision history Table 1. Document revision history Date Revision 27-Feb-2008 1 Changes Initial release. 3/4 STEVAL-ILL008V1 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 AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT RECOMMENDED, 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. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK. 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. © 2008 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 4/4