24AA64/24LC64/24FC64
7.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 7-1.
TABLE 7-1:
Name
A0
A1
A2
V
SS
SDA
SCL
WP
V
CC
PIN FUNCTION TABLE
PDIP
1
2
3
4
5
6
7
8
SOIC
1
2
3
4
5
6
7
8
TSSOP
1
2
3
4
5
6
7
8
DFN
1
2
3
4
5
6
7
8
MSOP
1
2
3
4
5
6
7
8
Description
Chip Address Input
Chip Address Input
Chip Address Input
Ground
Serial Address/Data I/O
Serial Clock
Write-Protect Input
+1.7V to 5.5V Power Supply
7.1
A0, A1, A2 Chip Address Inputs
7.3
Serial Clock (SCL)
The A0, A1 and A2 inputs are used by the 24XX64 for
multiple device operation. The levels on these inputs
are compared with the corresponding bits in the slave
address. The chip is selected if the compare is true.
Up to eight devices may be connected to the same bus
by using different Chip Select bit combinations. These
inputs must be connected to either V
CC
or V
SS
.
In Most applications, the chip address inputs A0, A1
and A2 are hard-wired to logic ‘0’ or logic ‘1’. For
applications in which these pins are controlled by a
microcontroller or other programmable device, the chip
address pins must be driven to logic ‘0’ or logic ‘1’
before normal device operation can proceed.
The SCL input is used to synchronize the data transfer
from and to the device.
7.4
Write-Protect (WP)
This pin must be connected to either V
SS
or V
CC
. If tied
to V
SS
, write operations are enabled. If tied to V
CC
,
write operations are inhibited but read operations are
not affected.
7.2
Serial Data (SDA)
SDA is a bidirectional pin used to transfer addresses
and data into and out of the device. Since it is an open-
drain terminal, the SDA bus requires a pull-up resistor
to V
CC
(typical 10 kΩ for 100 kHz, 2 kΩ for 400 kHz).
For normal data transfer, SDA is allowed to change
only during SCL low. Changes during SCL high are
reserved for indicating the Start and Stop conditions.
DS21189L-page 12
©
2007 Microchip Technology Inc.
MICROCHIP [ MICROCHIP TECHNOLOGY ]
