Datasheet

ADM1062
Rev. C | Page 32 of 36
8
• To set up a 2-byte EEPROM address for a subsequent read,
write, block read, block write, or page erase. In this case, the
command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The only data byte is the low
byte of the EEPROM address, as shown in Figure 45.
04433-042
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 76
Figure 45. Setting an EEPROM Address
Because a page consists of 32 bytes, only the three MSBs
of the address low byte are important for page erasure. The
lower five bits of the EEPROM address low byte specify the
addresses within a page and are ignored during an erase
operation.
• To write a single byte of data to the EEPROM. In this case,
the command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The first data byte is the low
byte of the EEPROM address, and the second data byte is
the actual data, as shown in Figure 46.
04433-043
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
AA
2413 5 7
A
9
DATA
86
P
10
Figure 46. Single Byte Write to the EEPROM
Block Write
In a block write operation, the master device writes a block of
data to a slave device. The start address for a block write must
have been set previously. In the ADM1062, a send byte opera-
tion sets a RAM address, and a write byte/word operation sets
an EEPROM address, as follows:
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address followed by
the write bit (low).
3.
The addressed slave device asserts an ACK on SDA.
4.
The master sends a command code that tells the slave
device to expect a block write. The ADM1062 command
code for a block write is 0xFC (1111 1100).
5.
The slave asserts an ACK on SDA.
6.
The master sends a data byte that tells the slave device how
many data bytes are being sent. The SMBus specification
allows a maximum of 32 data bytes in a block write.
7.
The slave asserts an ACK on SDA.
8.
The master sends N data bytes.
9.
The slave asserts an ACK on SDA after each data byte.
10.
The master asserts a stop condition on SDA to end the
transaction.
04433-044
SLAVE
ADDRESS
SWA
2
COMMAND 0xFC
(BLOCK WRITE)
413
A
5
BYTE
COUNT
6
A
7
A
910
A PA
DATA
1
8
DATA
N
DATA
2
Figure 47. Block Write to the EEPROM or RAM
Unlike some EEPROM devices that limit block writes to within
a page boundary, there is no limitation on the start address
when performing a block write to EEPROM, except when
• There must be at least N locations from the start address to
the highest EEPROM address (0xFBFF) to avoid writing to
invalid addresses.
• An address crosses a page boundary. In this case, both
pages must be erased before programming.
Note that the ADM1062 features a clock extend function for
writes to EEPROM. Programming an EEPROM byte takes
approximately 250 μs, which limits the SMBus clock for repeated
or block write operations. The ADM1062 pulls SCL low and
extends the clock pulse when it cannot accept any more data.
READ OPERATIONS
The ADM1062 uses the following SMBus read protocols.
Receive Byte
In a receive byte operation, the master device receives a single
byte from a slave device, as follows:
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address followed by the
read bit (high).
3.
The addressed slave device asserts an ACK on SDA.
4.
The master receives a data byte.
5.
The master asserts a NACK on SDA.
6.
The master asserts a stop condition on SDA, and the
transaction ends.
In the ADM1062, the receive byte protocol is used to read a
single byte of data from a RAM or EEPROM location whose
address has previously been set by a send byte or write
byte/word operation, as shown in Figure 48.
04433-045
23145
SLAVE
ADDRESS
S R DATA PA
6
A
Figure 48. Single Byte Read from the EEPROM or RAM