SLE4442 Siemens, SLE4442 Datasheet - Page 10

• Manufacturer Part Number: SLE4442
• Description: (SLE4432 / SLE4442) 256 Byte EEPROM
• Manufacturer: Siemens

2.1
Figure 1
Memory Overwiew
SLE 4432
The SLE 4432 consists of 256 x 8 bit EEPROM main memory and a 32-bit protection memory with
PROM functionality. The main memory is erased and written byte by byte. When erased, all 8 bits
of a data byte are set to logical one. When written, the information in the individual EEPROM cells
is, according to the input data, altered bit by bit to logical zeros (logical AND between the old and the
new data in the EEPROM). Normally a data change consists of an erase and write procedure. It
depends on the contents of the data byte in the main memory and the new data byte whether the
EEPROM is really erased and/or written. If none of the 8 bits in the addressed byte requires a zero-
to-one transition the erase access will be suppressed. Vice versa the write access will be
suppressed if no one-to-zero transition is necessary. The write and the erase operation takes at
least 2.5 ms each.
Each of the first 32 bytes can be irreversibly protected against data change by writing the
corresponding bit in the protection memory. Each data byte in this address range is assigned to one
bit of the protection memory and has the same address as the data byte in the main memory which
it is assigned to. Once written the protection bit cannot be erased (PROM).
Semiconductor Group
Memory Overview
8
SLE 4432
SLE 4442