5.0 or 3.3 V, 256 Kbit (32 Kbit x 8) TIMEKEEPER® SRAM

The M48T37Y/V TIMEKEEPER®RAM is a 32 Kb x 8 non-volatile static RAM and real-time clock. The monolithic chip is available in a special package which provides a highly integrated battery-backed memory and real-time clock solution.

The 44-lead, 330 mil SOIC package 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/crystal 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 packages are shipped separately in plastic anti-static tubes or in tape & reel form. For the 44-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
  • Frequency test output for real-time clock software calibration
  • Automatic power-fail chip deselect and WRITE protection
  • Watchdog timer
  • WRITE protect voltage (VPFD = Power-fail deselect voltage):
    • M48T37Y: VCC = 4.5 to 5.5 V 4.2 V ≤ VPFD ≤ 4.5 V
    • M48T37V: VCC = 3.0 to 3.6 V 2.7 V ≤ VPFD ≤ 3.0 V
  • Packaging includes a 44-lead SOIC and SNAPHAT® top (to be ordered separately)
  • SOIC package provides direct connection for a SNAPHAT® top which contains the battery and crystal
  • Microprocessor power-on reset (valid even during battery backup mode)
  • Programmable alarm output active in the battery backup mode
  • Battery low flag
  • RoHS compliant
    • Lead-free second level interconnect

Circuit Diagram

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Technical Documentation

Product Specifications
Description Version Size
DS1898 DS1898: 5.0 or 3.3 V, 256 Kbit (32 Kbit x 8) TIMEKEEPER® SRAM 9.1 508 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
AN1216 AN1216: Implementing a periodic alarm with TIMEKEEPER® and serial real-time clocks (RTCs) 2.0 192 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
AN968 AN968: VMEbus TIMEKEEPER® requirements 2.0 94 KB

HW Model, CAD Libraries & SVD

HW Model, CAD Libraries & SVD
Description Version Size
Ibis model 1.0 15 KB

Quality & Reliability

Product Certifications
Description Version Size
Products Underwriter Laboratories (UL) Information 2.1 543 KB
Support & Community

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

(*) 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**
M48T37V-10MH1F ActiveSO-44IndustrialEcopack1 0 0

(**) 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.