24LC22A-I Datasheet, PDF (13/24 Pages) Microchip Technology – 2K VESA E-EDID Serial EEPROM

24LC22A
FIGURE 7-3:
SEQUENTIAL READ
Bus Activity
Master
Control
Byte
Data n
Data n + 1
Data n + 2
SDA Line
A
A
A
A
C
C
C
C
Bus Activity
K
K
K
K
S
Data n + x
T
O
P
P
N
O
A
C
K
8.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 8-1.
TABLE 8-1: PIN FUNCTION TABLE
Name
VSS
SDA
SCL
VCLK
VCC
NC
Function
Ground
Serial Address/Data I/O
Serial Clock (Bidirectional mode)
Serial Clock (Transmit-Only mode)
+2.5V to 5.5V Power Supply
No Internal Connection
8.1 Serial Address/Data Input/Output
(SDA)
This pin is used to transfer addresses and data into and
out of the device, 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 SDA pin. This pin 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).
For normal data transfer in the Bidirectional mode, SDA
is allowed to change only during SCL low. Changes
during SCL high are reserved for indicating the Start
and Stop conditions.
8.2 Serial Clock (SCL)
This pin is the clock input for the Bidirectional mode,
and is used to synchronize 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 Bidirec-
tional mode. It must remain high for the chip to continue
operation in the Transmit-Only mode.
8.3 Serial Clock (VCLK)
This pin is the clock input for the Transmit-Only mode
(DDC1). 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.
© 2007 Microchip Technology Inc.
DS21683B-page 13