 2004 Microchip Technology Inc.

DS21140F-page 13

24LC41

8.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 8-1.

TABLE 8-1:

PIN FUNCTION TABLE

8.1

DSDA

This pin is used to transfer addresses and data into and

out of the DDC Monitor Port, when the device is in the

Bidirectional mode. In the Transmit-only mode, which

only allows data to be read from the device, data is also

transferred on the DSDA pin. This pin is an open drain

terminal, therefore the DSDA bus requires a pull-up

Ω for 100 kHz, 2 KΩ for

400 kHz).

For normal data transfer in the Bidirectional mode,

DSDA is allowed to change only during DSCL or MSDA

low. Changes during DSCL high are reserved for

indicating the Start and Stop conditions.

8.2

DSCL

This pin is the clock input for the DDC Monitor Port

while in the Bidirectional mode, and is used to synchro-

nize data transfer to and from the device. It is also used

as the signaling input to switch the device from the

Transmit-only mode to the Bidirectional mode. It must

remain high for the chip to continue operation in the

Transmit-only mode.

8.3

VCLK/DWP

This pin is the clock input for the DDC Monitor Port

while in the Transmit-only mode. In the Transmit-only

mode, each bit is clocked out on the rising edge of this

signal. In the Bidirectional mode, a high logic level is

required on this pin to enable write capability.

8.4

MSCL

This pin is the clock input for the Microcontroller Access

Port, and is used to synchronize data transfer to and

from the device.

8.5

MSDA

This pin is used to transfer addresses and data into and

out of the Microcontroller Access Port. This pin is an

open drain terminal, therefore the MSDA bus requires

Ω for 100 kHz,

2K

Ω for 400 kHz).

MSDA is allowed to change only during MSCL low.

Changes during MSCL high are reserved for indicating

the Start and Stop conditions.

8.6

MWP

This pin is used to write-protect the 4K memory array

for the Microcontroller Access Port.

If tied to Vss, normal memory operation is enabled

(read/write the entire memory).

memory will be write-protected. Read operations are

not affected.

Name

Function

DSCL

Serial Clock for DDC Bidirectional

mode (DDC2)

DSDA

Serial Address and Data I/O

(DDC Bus)

VCLK/DWP

Serial Clock for DDC Transmit-only

mode (DDC1)/Write-Protect

MSCL

Serial clock for 4 Kbit MCU port

MSDA

Serial Address and Data I/O for

4 Kbit MCU port

MWP

Hardware write-protect for 4 Kbit

MCU port

Ground

+2.5V to +5.5V power supply