x45620 Intersil Corporation, x45620 Datasheet - Page 17

• Manufacturer Part Number: x45620
• Description: Dual Voltage Monitor With Integrated System Battery Switch And Eeprom
• Manufacturer: Intersil Corporation

Figure 15. Random Read Sequence
Figure 16. Sequential Read Sequence
Sequential Read
Sequential reads can be initiated as either a current
address read or random read. The first Data Byte is
transmitted as with the other modes; however, the
master now responds with an acknowledge, indicating
it requires additional data. The device continues to
output data for each acknowledge received. The master
terminates the read operation by not responding with an
acknowledge and then issuing a stop condition.
The data output is sequential, with the data from
address n followed by the data from address n + 1.
The address counter for read operations increments
through all byte addresses, allowing the entire memory
contents to be read during one operation. At the end of
the address space the counter “rolls over” to address
0000h and the device continues to output data for
each acknowledge received. Refer to Figure 16 for the
acknowledge and data transfer sequence.
CONTROL REGISTER (CR)
The Control Register is located in an area logically
separated from the array and is only accessible via a
byte write to the register address of FFFFH. The Con-
trol Register is physically part of the array.
The CR can only be modified by performing a byte write
operation directly to the address of the register and only
one data byte is allowed for each register write operation.
Prior to initiating a nonvolatile write to the CR, the WEL
and RWEL bits must be set using a two step process,
with the whole sequence requiring 3 steps.
Signals from
Signals from
the Master
SDA Bus
the Slave
Signals from
Signals from
the Master
SDA Bus
the Slave
R
S
T
A
T
S
1 0 1 0
Address
S
Slave
17
Address
Slave
0
S
1
S
S
1
0
S
1
0
0
A
C
K
A
C
K
Word Address
Data
Byte 1
(1)
C
A
K
X45620
A
C
K
Word Address
Data
(2)
Byte 0
The user must issue a stop, after sending this byte to
the register, to initiate the high voltage cycle that
writes PUP, WD1, WD0, BP1, BP0 and WPEN to the
nonvolatile bits. The part will not acknowledge any
data bytes written after the first byte is entered. A stop
must also be issued after a volatile register write oper-
ation to put the device into Standby. After a write to the
CR, the address counter contents are undefined.
The state of the CR can be read by performing a ran-
dom read at the address of the register at any time.
Only one byte is read by the register read operation.
The part will reset itself after the first byte is read. The
master should supply a stop condition to be consistent
with the bus protocol, but a stop is not required to end
this operation. After the read of the CR, the address
counter contents are reset to zero, but the user will be
told these bits are undefined and instructed to do a
random read.
Table 1. Control Register
RWEL: Register Write Enable Latch (Volatile)
The RWEL bit must be set to “1” prior to a write to
Control Register.
WPEN WD1
7
C
A
K
(n is any integer greater than 1)
A
C
K
S
R
S
T
A
T
6
(n–1)
Data
Address
Slave
WD0 BP1 BP0 RWEL WEL PUP
5
A
C
K
1
4
A
C
K
Data
(n)
3
Data
2
O
S
T
P
P
O
P
S
P
T
1
July 29, 2005
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