IS34C02
The IS34C02 is a device specifically designed for use in the vastly popular DDR
memory module. During computer boot-up this EEPROM provides serial presence detect
(SPD) data for the Bios, such as module manufacturer, DRAM configuration, speed,
etc. A permanent write protection feature can be enabled by the module manufacturer
to protect the contents of half the array. The IS34C02 can also be used in other
types of memory modules or even non-module applications, depending on the needs
of the OEM. The most popular package type for this application is TSSOP(8).
An
electrically erasable PROM device that uses the standard 2-wire interface for
communications, the IS34C02 contains a memory array of 2,048-bits (256 x 8),
and is further subdivided into 16 pages of 16 bytes each for page-write mode.
The software write-protection feature is initiated with a unique irreversible
instruction. After this command is transmitted, the first 128 bytes of the array
become permanently read-only. This feature is popular in applications like DRAM
DIMMs to retain DRAM related data. This EEPROM is offered in wide operating voltages
of 1.8V to 5.5V (IS34C02-2) and 2.5V to 5.5V (IS34C02-3) to be compatible with
most application voltages. ISSI designed the IS34C02 as a low-cost and low-power
2-wire EEPROM solution. The devices are packaged in 8-pin SOIC, and 8-pin TSSOP,
and 8-pin MSOP.
IS24C02B
The IS24C02B is a general purpose I²C EEPROM, but there is a strong demand
for this type of device in various types of DRAM modules. Memory module manufacturers
might use this general purpose EEPROM instead of IS34C02 if they do not need permanent
write protection. IS24C02B conforms to industry-standard functionality, so it
can be used in a wide variety of applications. The most popular package types
for memory modules are SOIC(8) and TSSOP(8).
The
IS24C01B/02B maintains compatibility with the popular 2-wire bus protocol, so
it is easy to use in applications implementing this bus type. The simple bus consists
of the Serial Clock wire (SCL) and the Serial Data wire (SDA). Using the bus,
a Master device such as a microcontroller is usually connected to one or more
Slave devices such as this device. The bit stream over the SDA line includes a
series of bytes, which identifies a particular Slave device, an instruction, an
address within that Slave device, and a series of data, if appropriate. The IS24C01B/02B
has a Write Protect pin (WP) to allow blocking of any write instruction transmitted
over the bus. |
