AT24C256C
Pin Descriptions
2.
Pin Descriptions
The descriptions of the pins are listed in
Table 2-1. Pin Function Table
Name
A0(2)
A1(2)
A2(2)
GND
SDA
SCL
WP(2)
VCC
8‑Lead SOIC
1
2
3
4
5
6
7
8
8‑Lead TSSOP
1
2
3
4
5
6
7
8
8‑Pad UDFN(1)
1
2
3
4
5
6
7
8
8‑Ball VFBGA
1
2
3
4
5
6
7
8
Function
Device Address Input
Device Address Input
Device Address Input
Ground
Serial Data
Serial Clock
Write-Protect
Device Power Supply
Note:
1. The exposed pad on this package can be connected to GND or left floating.
2. If the A0, A1, A2 or WP pins are not driven, they are internally pulled down to GND. In order to
operate in a wide variety of application environments, the pull‑down mechanism is intentionally
designed to be somewhat strong. Once these pins are biased above the CMOS input buffer’s trip
point (~0.5 x V
CC
), the pull‑down mechanism disengages. Microchip recommends connecting these
pins to a known state whenever possible.
2.1
Device Address Inputs (A0, A1, A2)
The A0, A1 and A2 pins are device address inputs that are hard-wired (directly to GND or to V
CC
) for
compatibility with other 2-wire Serial EEPROM devices. When the pins are hard-wired, as many as eight
devices may be addressed on a single bus system. A device is selected when a corresponding hardware
and software match is true. If these pins are left floating, the A0, A1 and A2 pins will be internally pulled
down to GND. However, due to capacitive coupling that may appear in customer applications, Microchip
recommends always connecting the address pins to a known state. When using a pull‑up resistor,
Microchip recommends using 10 kΩ or less.
2.2
Ground
The ground reference for the power supply. GND should be connected to the system ground.
2.3
Serial Data (SDA)
The SDA pin is an open‑drain bidirectional input/output pin used to serially transfer data to and from the
device. The SDA pin must be pulled high using an external pull‑up resistor (not to exceed 10 kΩ in value)
and may be wire-ORed with any number of other open‑drain or open‑collector pins from other devices on
the same bus.
2.4
Serial Clock (SCL)
The SCL pin is used to provide a clock to the device and to control the flow of data to and from the
device. Command and input data present on the SDA pin is always latched in on the rising edge of SCL,
©
2018 Microchip Technology Inc.
Datasheet
DS20006042A-page 5
MICROCHIP [ MICROCHIP TECHNOLOGY ]
