M34E04B Datasheet, PDF (6/35 Pages) STMicroelectronics – 4-Kbit Serial Presence Detect EEPROM compatible

Description
1
Description
M34E04B
The M34E04B is a 512-byte EEPROM device designed to operate the SMBus bus in the
1.7 V - 3.6 V voltage range, with a maximum of 1 MHz transfer rate in the 2.2 V - 3.6 V
voltage range, over the JEDEC defined ambient temperature of 0°C / 95°C.
The M34E04B includes a 4-Kbit serial EEPROM organized as two pages of 256 bytes each,
or 512 bytes of total memory. Each page is composed of two 128-byte blocks. The device is
able to selectively lock the data in any or all of the four 128-byte blocks. Designed
specifically for use in DRAM DIMMs (Dual Inline Memory Modules) with Serial Presence
Detect, all the information concerning the DRAM module configuration (such as its access
speed, its size, its organization) can be kept write-protected in one or more memory blocks.
The M34E04B device is protocol-compatible with the previous generation of 2-Kbit devices,
M34E02. The page selection method allows commands used with legacy devices such as
M34E02 to be applied to the lower or upper pages of the EEPROM.
Individually locking a 128-byte block may be accomplished using a software write protection
mechanism in conjunction with a high input voltage V_HV on input SA0. By sending the
device a specific SMBus sequence, each block may be protected from writes until the write
protection is electrically reversed using a separate SMBus sequence which also requires
V_HV on input SA0. The write protection for all four blocks is cleared simultaneously.
Figure 1. Logic diagram
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Figure 2. 8-pin package connections (top view)
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1. See the Package information section for package dimensions, and how to identify pin 1.
2. NC: Not connected
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DocID028428 Rev 1