CAT24C02C Datasheet, PDF (5/9 Pages) Catalyst Semiconductor – 2K-Bit Serial E2PROM

CAT24C02C
START Condition
The START Condition precedes all commands to the
device, and is defined as a HIGH to LOW transition of
SDA when SCL is HIGH. The CAT24C02C monitor the
SDA and SCL lines and will not respond until this
condition is met.
STOP Condition
A LOW to HIGH transition of SDA when SCL is HIGH
determines the STOP condition. All operations must end
with a STOP condition.
DEVICE ADDRESSING
The bus Master begins a transmission by sending a
START condition. The Master then sends the address
of the particular slave device it is requesting. The four
most significant bits of the 8-bit slave address are fixed
as 1010 for the CAT24C02C (see Fig. 5). The next three
significant bits are all zeros. The last bit of the slave
address specifies whether a Read or Write operation is
to be performed. When this bit is set to 1, a Read
operation is selected, and when set to 0, a Write opera-
tion is selected.
After the Master sends a START condition and the slave
address byte, the CAT24C02C monitors the bus and
responds with an acknowledge (on the SDA line). The
CAT24C02C then performs a Read or Write operation
depending on the state of the R/W bit.
Acknowledge
After a successful data transfer, each receiving device is
required to generate an acknowledge. The acknowledg-
ing device pulls down the SDA line during the ninth clock
cycle, signaling that it received the 8 bits of data.
Figure 4. Acknowledge Timing
The CAT24C02C responds with an acknowledge after
receiving a START condition and its slave address. If the
device has been selected along with a write operation,
it responds with an acknowledge after receiving each 8-
bit byte.
When the CAT24C02C is in a READ mode it transmits
8 bits of data, releases the SDA line, and monitors the
line for an acknowledge. Once it receives this acknowl-
edge, the CAT24C02C will continue to transmit data. If
no acknowledge is sent by the Master, the device
terminates data transmission and waits for a STOP
condition.
WRITE OPERATIONS
Byte Write
In the Byte Write mode, the Master device sends the
START condition and the slave address information
(with the R/W bit set to zero) to the Slave device. After
the Slave generates an acknowledge, the Master sends
the byte address that is to be written into the address
pointer of the CAT24C02C. After receiving another
acknowledge from the Slave, the Master device trans-
mits the data byte to be written into the addressed
memory location. The CAT24C02C acknowledge once
more and the Master generates the STOP condition, at
which time the device begins its internal programming
cycle to nonvolatile memory. While this internal cycle is
in progress, the device will not respond to any request
from the Master device.
Page Write
The CAT24C02C writes up to 16 bytes of data in a single
write cycle, using the Page Write operation. The Page
Write operation is initiated in the same manner as
counter will ‘wrap around’ to address 0 and continue to
SCL FROM
1
MASTER
DATA OUTPUT
FROM TRANSMITTER
DATA OUTPUT
FROM RECEIVER
START
5
8
9
ACKNOWLEDGE
5020 FHD F06
Doc. No. 25086-00 8/99 S-1