CAT24FC32A

6

Doc. No. 1048, Rev. F

WP: Write Protect

This input controls the device write protect feature. WP

memory. When this pin is connected to Vcc, the entire

memory is write protected. When left floating, an internal

pull-down resistor on this input will keep the memory

unprotected. Read operations are not affected.

A0, A1, A2: Device Address Inputs

These inputs are used for extended addressing capability.

left unconnected. When hardwired, up to eight

CAT24FC32As may be addressed on a single bus

system. When the pins are left unconnected, the default

values are zero. The levels on these inputs are compared

with corresponding bits, A2, A1, A0, from the slave

address byte.

PIN DESCRIPTION

SCL: Serial Clock

The serial clock input clocks all data transferred into or

out of the device. The SCL line requires a pull-up resistor

if it is driven by an open drain output.

SDA: Serial Data/Address

The bidirectional serial data/address pin is used to

transfer all data into and out of the device. The SDA pin

is an open drain output and can be wire-ORed with other

open drain or open collector outputs. A pull-up resistor

must be connected from SDA line to Vcc. The value of

the pull-up resistor, Rp, can be calculated based on

minimum and maximum values from Figure 4 and Figure

5. (see Note).

Figure 4

Figure 5

can be a resistor. For bus loads between 200pF and 400pF, the pull-up device can be a current source

(Imax=3mA) or a switched resistor circuit.

Minimum RP as a Function of Supply Voltage

(IOL = 3mA @ VOLmax)

1

0.5

0

1.6

2

2.4

2.8

3.2

3.6

VCC (V)

Minimum RP Value versus Bus Capacitance

(Fast Mode I2C Bus / tr max = 300ns)

8.00

7.00

6.00

5.00

4.00

3.00

2.00

1.00

0.00

50

100

150

200

250

300

350

400

Cbus (pF)