24AA256UID Datasheet, PDF (4/28 Pages) Microchip Technology – 256K I2C™ Serial EEPROM

24AA256UID
FIGURE 1-1:
BUS TIMING DATA
SCL
SDA
IN
SDA
OUT
5
7
3
6
14
2
8
D3
9
11
4
10
12
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Name
8-pin
PDIP
8-pin 8-pin
SOIC TSSOP
Function
A0
1
1
1 User Configurable Chip Select
A1
2
2
2 User Configurable Chip Select
A2
3
3
3 User Configurable Chip Select
VSS
SDA
4
4
5
5
4 Ground
5 Serial Data
SCL
6
6
6 Serial Clock
NC
7
7
7 Not Connected
VCC
8
8
8 +1.7V to 5.5V
2.1 A0, A1, A2 Chip Address Inputs
The A0, A1 and A2 inputs are used by the 24AA256UID
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 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 VCC or VSS.
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.
2.2 Serial Data (SDA)
This is a bidirectional pin used to transfer addresses
and data into and 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).
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 to
and from the device.
DS20005215A-page 4
 2013 Microchip Technology Inc.