X40420 Datasheet, PDF (11/25 Pages) Xicor Inc. – Dual Voltage Monitor with Integrated CPU Supervisor and System Battery Switch

X40420/X40421 – Preliminary
Figure 10. Byte Write Sequence
Signals from
the Master
SDA Bus
S
t
a
r
Slave
Address
t
0
Byte
Address
S
t
Data
o
p
Signals from
the Slave
A
A
A
C
C
C
K
K
K
Page Write
The device is capable of a page write operation. It is
initiated in the same manner as the byte write opera-
tion; but instead of terminating the write cycle after the
first data byte is transferred, the master can transmit
an unlimited number of 8-bit bytes. After the receipt of
each byte, the device will respond with an acknowl-
edge, and the address is internally incremented by
one. The page address remains constant. When the
counter reaches the end of the page, it “rolls over” and
goes back to ‘0’ on the same page.
This means that the master can write 16 bytes to the
page starting at any location on that page. If the mas-
ter begins writing at location 10, and loads 12 bytes,
then the first 6 bytes are written to locations 10 through
15, and the last 6 bytes are written to locations 0
through 5. Afterwards, the address counter would point
to location 6 of the page that was just written. If the
master supplies more than 16 bytes of data, then new
data over-writes the previous data, one byte at a time.
Figure 11. Page Write Operation
Signals from
the Master
SDA Bus
S
t
a
Slave
Address
r
t
101 00 0
Byte
Address
(1 ≤ n ≤ 16)
Data
(1)
S
Data
t
(n)
o
p
Signals from
the Slave
A
A
A
A
C
C
C
C
K
K
K
K
Figure 12. Writing 12 bytes to a 16-byte page starting at location 10.
6 Bytes
6 Bytes
address
=5
address pointer
ends here
Addr = 6
address
10
address
n-1
The master terminates the Data Byte loading by issuing
a stop condition, which causes the device to begin the
nonvolatile write cycle. As with the byte write operation,
all inputs are disabled until completion of the internal
write cycle. See Figure 11 for the address, acknowl-
edge, and data transfer sequence.
REV 1.2.14 7/12/02
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Characteristics subject to change without notice. 11 of 25