5 V, 64 Kbit (8 Kb x 8) TIMEKEEPER® SRAM

The M48T08/18/08Y TIMEKEEPER®RAM is an 8 K x 8 non-volatile static RAM and real-time clock which is pin and function compatible with the DS1643. The monolithic chip is available in two special packages to provide a highly integrated battery-backed memory and real-time clock solution.

The M48T08/18/08Y is a non-volatile pin and function equivalent to any JEDEC standard 8 K x 8 SRAM. It also easily fits into many ROM, EPROM, and EEPROM sockets, providing the non-volatility of PROMs without any requirement for special WRITE timing or limitations on the number of WRITEs that can be performed.

The 28-pin, 600 mil DIP CAPHAT™ houses the M48T08/18/08Y silicon with a quartz crystal and a long-life lithium button cell in a single package.

The 28-pin, 330 mil SOIC provides sockets with gold-plated contacts at both ends for direct connection to a separate SNAPHAT® housing containing the battery and crystal. The unique design allows the SNAPHAT®battery package to be mounted on top of the SOIC package after the completion of the surface mount process. Insertion of the SNAPHAT®housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface-mounting. The SNAPHAT®housing is keyed to prevent reverse insertion.

The SOIC and battery/crystal packages are shipped separately in plastic anti-static tubes or in tape & reel form. For the 28-lead SOIC, the battery/crystal package (e.g., SNAPHAT®) part number is “M4T28-BR12SH” or “M4T32-BR12SH”.

Key Features

  • Integrated ultra low power SRAM, real-time clock, power-fail control circuit, and battery
  • BYTEWIDE RAM-like clock access
  • BCD coded year, month, day, date, hours, minutes, and seconds
  • Typical clock accuracy of ±1 minute a month, at 25 °C
  • Automatic power-fail chip deselect and WRITE protection
  • WRITE protect VPFD = power-fail deselect voltage):
    • M48T08: VCC = 4.75 to 5.5 V; 4.5 V ≤ VPFD ≤ 4.75 V
    • M48T18/T08Y: VCC = 4.5 to 5.5 V; 4.2 V ≤ VPFD ≤ 4.5 V
  • Software controlled clock calibration for high accuracy applications
  • Self-contained battery and crystal in the CAPHAT DIP package
  • Packaging includes a 28-lead SOIC and SNAPHAT® top (to be ordered separately)
  • SOIC package provides direct connection for a snaphat top which contains the battery and crystal
  • Pin and function compatible with DS1643 and JEDEC standard 8 K x 8 SRAMs
  • RoHS compliant
    • Lead-free second level interconnect

Circuit Diagram

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circuit_diagram_2411_thumbnail.png

Design

Technical Documentation

Product Specifications
Description Version Size
DS0494 DS0494: 5 V, 64 Kbit (8 Kb x 8) TIMEKEEPER® SRAM 11.1 492 KB
Application Notes
Description Version Size
AN1011 AN1011: Battery technology used in NVRAM and real-time clock (RTC) products from ST 4.0 248 KB
AN934 AN934: How to use the digital calibration feature in TIMEKEEPER® and serial real-time clock (RTC) products 4.1 123 KB
AN923 AN923: Managing century information using serial real-time clocks and TIMEKEEPER® NVRAMs 4.0 142 KB
AN1009 AN1009: Negative undershoot NVRAM data corruption 2.0 82 KB
AN1012 AN1012: Predicting the battery life and data retention period of NVRAMs and serial RTCs 4.1 439 KB
AN925 AN925: Time update in ST's TIMEKEEPER® devices 2.0 119 KB

Quality & Reliability

Product Certifications
Description Version Size
Products Underwriter Laboratories (UL) Information 2.1 543 KB
Products Underwriter Laboratories (UL) Information 2.1 162 KB

Sample & Buy

Part Number Package Packing Type Marketing Status Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
M48T08-100PC1 PDIP 28 .7 Tube Active - NEC EAR99 MALAYSIA MORE INFO DISTRIBUTOR AVAILABILITY
M48T08-150PC1 PDIP 28 .7 Tube Active - NEC EAR99 MALAYSIA MORE INFO DISTRIBUTOR AVAILABILITY
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(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
M48T08-100PC1 ActivePDIP 28 .7IndustrialEcopack1
M48T08-150PC1 ActivePDIP 28 .7IndustrialEcopack1
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(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

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