24lcs21 Microchip Technology Inc., 24lcs21 Datasheet - Page 13

• Manufacturer Part Number: 24lcs21
• Description: 1k 2.5v Dual Mode I 2 C? Serial Eeprom
• Manufacturer: Microchip Technology Inc.

8.0
TABLE 8-1:
8.1
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
V
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.
FIGURE 8-1:
© 2005 Microchip Technology Inc.
CC
Master
SDA Line
Bus Activity
Bus Activity
(typical 10 K
Name
V
SDA
SCL
V
V
WP
NC
CLK
CC
SS
PIN DESCRIPTIONS
SDA
Control
Byte
PIN FUNCTION TABLE
Serial Clock (Transmit-Only mode)
for 100 kHz, 2 K for 400 kHz).
Serial Clock (Bidirectional mode)
A
C
K
+2.5V to 5.5V Power Supply
SEQUENTIAL READ
Write-protect (active low)
Serial Address/Data I/O
No Connection
Data n
Function
Ground
C
A
K
Data n+1
A
C
K
8.2
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
Bidirectional mode. It must remain high for the chip to
continue operation in the Transmit-Only mode.
8.3
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.
8.4
This pin is used for flexible write protection of the
24LCS21. When the last memory location (7Fh) is
written with any data, this pin is enabled and
determines the write capability of the 24LCS21
(Figure 6-1).
Data n+2
SCL
VCLK
WP
A
C
K
24LCS21
Data n+X
DS21127F-page 13
N
O
A
C
K
O
S
T
P
P