SA24C1024 Datasheet, PDF (14/27 Pages) List of Unclassifed Manufacturers – 1024Kb EEPROM IIC

Pin Descriptions
Serial Clock (SCL)
The SCL input is used to clock all data into
and out of the device.
Serial Data (SDA)
SDA is a bidirectional pin used to transfer
data into and out of the device. It is an
open drain output and may be wire–ORed
with any number of open drain or open
collector outputs.
Write Protect (WP)
Choice 1: Full Array Write Protect
If pulled HIGH, Write operations are not
executed, and Read operations are
possible. If pulled LOW, normal operation
is enabled, and Read/Write over the entire
memory is possible.
This feature allows the user to assign the
entire memory as ROM, which can then be
protected against accidental programming.
When Write is disabled, the Slave address
and word address are acknowledged but
data is not.
This pin has an internal pulldown circuit.
However, on systems where write
protection is not required, it is
recommended that this pin be tied to V_SS.
SA24C1024 Datasheet
SAIFUN
14
Table 2. Write Protection Truth Table
WP "Less Than"
Pin Comparison
T/B Bit
Write
Allowed
1
YES
0
NO
1
NO
0
YES
1
YES
1
YES
1
NO
1
NO
0
Don't Care
Don't Care
YES
Device Selection Input – A1 (as
Appropriate)
This input serves as a chip select signal to
an EEPROM when multiple EEPROMs are
present on the same IIC bus. These inputs,
if present, should be connected to V_CC or
V_SS in a unique manner to enable proper
selection of an EEPROM among multiple
EEPROMs.
During a typical addressing sequence,
every EEPROM on the IIC bus compares
the configuration of these inputs to the
respective two MSBs of the Device/Page
Block selection information (which is part of
the Slave address) to determine a valid
selection. For example, if the two MSB bits
of the Device/Page Block selection are 0-0,
the EEPROM whose Device Selection
input (A1) is connected to the respective
V_SS is selected.
On the SA24C1024, only A1 is provided,
so the corresponding A2 bit in the
Device/Page Block selection should be set
to 0 during all accesses to the device.
These two pins have a weak internal
pulldown circuit.