ADM1064 Analog Devices, ADM1064 Datasheet - Page 24

• Manufacturer Part Number: ADM1064
• Manufacturer: Analog Devices

Specifications of ADM1064

• # Supplies Monitored: 10
• Volt Monitoring Accuracy: 1%
• # Output Drivers: 10
• Fet Drive/enable Output: Both
• Voltage Readback: 12-bit ADC
• Package: 40 ld LFCSP ,48 ld TQFP

ADM1064
The device also has several identification registers (read-only)
that can be read across the SMBus. Table 11 lists these registers
with their values and functions.
Table 11. Identification Register Values and Functions
Name
MANID
REVID
MARK1
MARK2
General SMBus Timing
Figure 31, Figure 32, and Figure 33 are timing diagrams for
general read and write operations using the SMBus. The SMBus
specification defines specific conditions for different types of
read and write operations, which are discussed in the Write
Operations and Read Operations sections.
The general SMBus protocol operates as follows:
Step 1
The master initiates data transfer by establishing a start condition,
defined as a high-to-low transition on the serial data line SDA,
while the serial clock-line SCL remains high. This indicates that
a data stream follows. All slave peripherals connected to the serial
bus respond to the start condition and shift in the next eight bits,
consisting of a 7-bit slave address (MSB first) plus an R/ W bit.
This bit determines the direction of the data transfer, that is,
whether data is written to or read from the slave device (0 =
write, 1 = read).
The peripheral whose address corresponds to the transmitted
address responds by pulling the data line low during the low
period before the ninth clock pulse, known as the acknowledge
bit, and by holding it low during the high period of this clock pulse.
Address
0xF4
0xF5
0xF6
0xF7
(CONTINUED)
(CONTINUED)
SDA
SCL
START BY
SDA
SCL
MASTER
0x41
0x02
0x00
0x00
Value
1
0
1
D7
1
Silicon revision
Function
Manufacturer ID for Analog
Devices
Software brand
Software brand
D6
SLAVE ADDRESS
0
FRAME 1
D5
0
D4
1
DATA BYTE
FRAME 3
A1
D3
Figure 31. General SMBus Write Timing Diagram
A0
D2
R/W
ACK. BY
D1
SLAVE
Rev. D | Page 24 of 32
9
D0
ACK. BY
SLAVE
1
9
D7
D6
1
All other devices on the bus remain idle while the selected device
waits for data to be read from or written to it. If the R/ W bit is
a 0, the master writes to the slave device. If the R/ W bit is a 1, the
master reads from the slave device.
Step 2
Data is sent over the serial bus in sequences of nine clock pulses:
eight bits of data followed by an acknowledge bit from the slave
device. Data transitions on the data line must occur during the
low period of the clock signal and remain stable during the high
period because a low-to-high transition when the clock is high
could be interpreted as a stop signal. If the operation is a write
operation, the first data byte after the slave address is a command
byte. This command byte tells the slave device what to expect next.
It may be an instruction telling the slave device to expect a block
write, or it may be a register address that tells the slave where
subsequent data is to be written. Because data can flow in only
one direction, as defined by the R/ W bit, sending a command to
a slave device during a read operation is not possible. Before a
read operation, it may be necessary to perform a write operation
to tell the slave what sort of read operation to expect and/or the
address from which data is to be read.
Step 3
When all data bytes have been read or written, stop conditions
are established. In write mode, the master pulls the data line high
during the 10th clock pulse to assert a stop condition. In read
mode, the master device releases the SDA line during the low
period before the ninth clock pulse, but the slave device does
not pull it low. This is known as a no acknowledge (NACK).
The master then takes the data line low during the low period
before the 10th clock pulse, and then high during the 10th clock
pulse to assert a stop condition.
D7
D5
COMMAND CODE
D4
D6
FRAME 2
D5
D3
D4
D2
DATA BYTE
FRAME N
D3
D1
ACK. BY
D2
D0
SLAVE
9
D1
D0
ACK. BY
SLAVE
9
MASTER
STOP
BY