STEVAL-ISA094V1 3 A step-down switching power supply demonstration board based on the L7981 (HSOP8) Data brief Features ■ 3 A DC output current ■ 4.5 V to 28 V input voltage ■ Output voltage adjustable from 0.6 V ■ 250 kHz switching frequency, programmable up to 1 MHz ■ Internal soft-start and enable ■ Low dropout operation: 100% duty cycle ■ Voltage feed-forward ■ Zero load current operation ■ Overcurrent and thermal protection ■ RoHS compliant STEVAL-ISA094V1 Description The STEVAL-ISA094V1 is a step-down switching power supply based on STMicroelectronics’ L7981 switching regulator in an HSOP8 package. The L7981 features an embedded power MOSFET and is capable of delivering up to 3 A of current to the load, depending on the application conditions. The input voltage can range from 4.5 V to 28 V, while the output voltage can be set from 0.6 V to VIN. Requiring a minimum number of external components, the device includes an internal 250 kHz switching frequency oscillator that can be externally adjusted up to 1 MHz. December 2011 Doc ID 022621 Rev 1 For further information contact your local STMicroelectronics sales office. 1/4 www.st.com 4 Schematic diagram STEVAL-ISA094V1 1 Schematic diagram Figure 1. STEVAL-ISA094V1 circuit schematic 5 6). 66 6 & 6 # N& ,! 39.# 6 6/54 ## , %. &37 &" '.$ '.$ #/-0 # $ 3403, 6 6/54 # N& 2 # P& !-6 2/4 Doc ID 022621 Rev 1 STEVAL-ISA094V1 2 Revision history Revision history Table 1. Document revision history Date Revision 23-Dec-2011 1 Changes Initial release. Doc ID 022621 Rev 1 3/4 STEVAL-ISA094V1 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 TWO AUTHORIZED ST REPRESENTATIVES, 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. © 2011 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 - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com 4/4 Doc ID 022621 Rev 1