AT24CS04 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'AT24CS04' PDF : 24 Pages View PDF
8. Device Addressing
Standard EEPROM Access: The 4-Kbit and 8-Kbit EEPROM device requires an 8-bit device address word following a
Start condition to enable the chip for a read or write operation.
The device address word consists of a mandatory ‘1010’ (Ah) sequence for the first four most significant bits as shown
in Figure 8-1 below. This is common to all Serial EEPROM devices.
The 4K EEPROM only uses the A2 and A1 device address bits with the third bit being a memory page address bit (P0).
The two device address bits must compare to their corresponding hard-wired input pins. Pin 1 is a no connect. The 8K
EEPROM only uses the A2 device address bit with the next two bits being for memory page addressing (P1, P0). The A2
must compare to its corresponding hard-wired A2 input pin. Pins 1 and 2 are not connected.
The eighth bit of the device address is the read/write operation select bit. A read operation is initiated if this bit is high and
a write operation is initiated if this bit is low.
Upon a compare of the device address, the EEPROM will output a zero. If a compare is not made, the chip will return to
a standby state.
Note:
For the SOT23 package offering, the 4-Kbit EEPROM software A2 and A1 bits in the device address word
must be set to zero to properly communicate. The 8-Kbit EEPROM software A2 bit in the device address
word must be set to zero to properly communicate in the SOT23 paclkage.
Serial Number Access: The AT24CS04 and AT24CS08 utilizes a separate memory block containing a factory
programmed 128-bit serial number. Access to this memory location is obtained by beginning the device address word
with a ‘1011’ (Bh) sequence.
The behavior of the next three bits remain the same as during a standard EEPROM addressing sequence. These three
bits must compare to their corresponding hard-wired input pins A2 and A1 (4-Kbit only) in order for the part to
acknowledge. The restrictions for these bits with a SOT23 package are the same when accessing the serial number
feature.
The eighth bit of the device address needs be set to a one to read the Serial Number. A zero in this bit position, other
than during a dummy write sequence to set the address pointer, will result in a unknown data read from the part. Writing
or altering the 128-bit serial number is not possible.
Further specific protocol is needed to read the serial number from of the device. See Read Operations on page 11 for
more details on accessing the special feature.
Table 8-1. Device Address
Density
4-Kbit
8-Kbit
Access Area
EEPROM
Serial Number
EEPROM
Serial Number
Bit 7
1
1
1
1
MSB
Bit 6
0
0
0
0
Bit 5
1
1
1
1
Bit 4
0
1
0
1
Bit 3
A2
A2
A2
A2
Bit 2
A1
A1
P1
0
Bit 1
P0
0
P0
0
Bit 0
R/W
1
R/W
1
LSB
Atmel AT24CS04/08 [PRELIMINARY DATASHEET] 10
8766B–SEEPR–8/12
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