I C™ Serial EEPROM Family Data Sheet - Microchip

3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1: PIN FUNCTION TABLE
Pin Name
8-Pin PDIP
and SOIC
8-Pin
TSSOP and
MSOP
A0 1 1 (1)
5-Pin SOT-23
24XX00
3.1 A0, A1, A2 Chip Address Inputs
The A0, A1 and A2 pins are not used by the 24XX01
through 24XX16 devices.
The A0, A1 and A2 inputs are used by the 24C01C,
24C02C, 24XX014, 24XX024, 24XX025 and the
24XX32 through 24XX1025 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.
For the 24XX128 and 24XX256 in the MSOP package
only, pins A0 and A1 are not connected.
Up to eight devices (two for the 24XX128 and
24XX256 MSOP package) may be connected to the
same bus by using different Chip Select bit
combinations.
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.
24AAXX/24LCXX/24FCXX
5-Pin SOT-23
All except
24XX00
8-Pin
5x6 DFN and
2x3 DFN
3.2 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 kΩ for 100 kHz, 2 kΩ 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.
3.3 Serial Clock (SCL)
This input is used to synchronize the data transfer to
and from the device.
3.4 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. See Table 1-1 for the write-protect
scheme of each device.
3.5 Power Supply (VCC)
Function
— — 1 User configurable Chip Select (3)(4)
A1 2 2 (1) — — 2 User configurable Chip Select (3)(4)
A2 3 3 — — 3 User configurable Chip Select (3)(4)
VSS 4 4 2 2 4 Ground
SDA 5 5 3 3 5 Serial Data
SCL 6 6 1 1 6 Serial Clock
(NC) — — 4 — — Not Connected
WP 7 (2)
7 (2)
— 5 7 Write-Protect Input
VCC 8 8 5 4 8 Power Supply
Note 1: Pins 1 and 2 are not connected for the 24XX128 and 24XX256 MSOP packages.
2: Pin 7 is not used for 24XX00, 24XX025 and 24C01C.
3: Pins A0, A1 and A2 are not used by some devices (no internal connections). See Table 1-1 for details.
4: Pin A2 should be tied to a Logic High in the 24XX1025 for proper operation.
Note: In the 24XX1025, the A2 pin is not configurable,
it must be tied to VCC in order for
this device to operate properly.
A VCC threshold detect circuit is employed which
disables the internal erase/write logic if VCC is below
1.5V at nominal conditions. For the 24C00, 24C01C
and 24C02C devices, the erase/write logic is disabled
below 3.8V at nominal conditions.
© 2007 Microchip Technology Inc. DS21930C-page 9