24AA1026_15 Datasheet, PDF (6/30 Pages) Microchip Technology – 1024K I2C�� Serial EEPROM

24AA1026/24LC1026/24FC1026
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
Name
NC
A1
A2
VSS
SDA
SCL
WP
VCC
PIN FUNCTION TABLE
PDIP
SOIC
SOIJ
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
Function
Not Connected
User Configurable Chip Select
User Configurable Chip Select
Ground
Serial Data
Serial Clock
Write-Protect Input
+1.7 to 5.5V (24AA1026)
+2.5 to 5.5V (24LC1026)
+1.8 to 5.5V (24FC1026)
2.1 A1, A2 Chip Address Inputs
The A1 and A2 inputs are used by the 24XX1026 for
multiple device operations. The levels on these inputs
are compared with the corresponding bits in the slave
address. The chip is selected if the comparison is true.
Up to four devices may be connected to the same bus
by using different Chip Select bit combinations. In most
applications, the chip address inputs 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.
3.0 FUNCTIONAL DESCRIPTION
The 24XX1026 supports a bidirectional 2-wire bus and
data transmission protocol. A device that sends data
onto the bus is defined as a transmitter and a device
receiving data as a receiver. The bus must be
controlled by a master device which generates the
Serial Clock (SCL), controls the bus access, and
generates the Start and Stop conditions while the
24XX1026 works as a slave. Both master and slave
can operate as a transmitter or receiver, but the master
device determines which mode is activated.
2.2 Serial Data (SDA)
This is a bidirectional pin used to transfer addresses
and data into and data out of the device. It is an
open-drain terminal, therefore, the SDA bus requires a
pull-up resistor to VCC (typical 10 k for 100 kHz, 2 k
for 400 kHz and 1 MHz).
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.
2.3 Serial Clock (SCL)
This input is used to synchronize the data transfer from
and to the device.
2.4 Write-Protect (WP)
This pin must be connected to either VSS or VCC. If tied
to VSS, write operations are enabled. If tied to VCC,
write operations are inhibited, but read operations are
not affected.
DS20002270E-page 6
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