AN1000 APPLICATION NOTE
ZEROPOWER and TIMEKEEPER SUPERVISOR Surface-Mount Solution
INTRODUCTION The ZEROPOWER and TIMEKEEPER SUPERVISORS from STMicroelectronics (such as the M40Z300 and the M48T201Y) offer all the advantages of using surface-mount technology, and are well suited to automatic assembly-line processes. Designed to be highly modular, they interface directly with commodity SRAM, and use a commercially available cell for the internal battery (which is easily replaceable). These devices are designed for lower system costs when compared to designs using competitors' hybrid products. Moreover, even though the ST products need an external SRAM chip, the footprint of the two chips together is still 80% of that of the competitors' single chip solutions. Figure 1 compares the footprint of a competitor's chip (not unlike MAXIM/Dallas Semiconductor's hybrid surface-mount PowerCap module) with an ST device connected to a 1Mbit (128K x 8) low power SRAM chip (perhaps from Hitachi, Sony or Samsung). The former solution might have a footprint of 0.965 by 0.930 inches (0.898 square inches), while the latter leads to a combined footprint of 0.916 by 0.787 inches (0.721 square inches). Figure 1. Footprint Comparison
0.965 inches 0.916 inches
0.930 inches
0.787 inches
AI02446
November 2001
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AN1000 - APPLICATION NOTE
CONTACT INFORMATION If you have any questions or suggestions concerning the matters raised in this document, please send them to the following electronic mail addresses:
apps.nvram@st.com ask.memory@st.com
(for application support) (for general inquiries)
Please remember to include your name, company, location, telephone number, and fax number.
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is registered trademark of STMicroelectronics All other names are the property of their respective owners. 2001 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. www.st.com
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