ADT7411 Datasheet, PDF (30/36 Pages) Analog Devices – SPI/I2C Compatible, 10-Bit Digital Temperature Sensor and 8-Channel ADC

ADT7411
1
9
1
9
SCL
SDA
1
START BY
MASTER
0
0
1 A2 A1 A0 R/W
P7
FRAME 1
SERIAL BUS ADDRESS BYTE
ACK. BY
ADT7411
1
SCL (CONTINUED)
P6 P5 P4 P3 P2 P1 P0
FRAME 2
ADDRESS POINTER REGISTER BYTE
9
ACK. BY
ADT7411
SDA (CONTINUED)
D7 D6 D5 D4 D3 D2 D1 D0
FRAME 3
DATA BYTE
ACK. BY STOP BY
ADT7411 MASTER
Figure 35. I²C—Writing to the Address Pointer Register Followed by a Single Byte of Data to the Selected Register
1
9
1
9
SCL
SDA
1
START BY
MASTER
0
0
1 A2 A1 A0 R/W
D7
ACK. BY
ADT7411
FRAME 1
SERIAL BUS ADDRESS BYTE
D6 D5 D4 D3 D2 D1 D0
NO ACK. BY STOP BY
MASTER MASTER
FRAME 2
SINGLE DATA BYTE FROM ADT7411
Figure 36. I²C—Reading a Single Byte of Data from a Selected Register
The part operates in a slave mode and requires an externally
applied serial clock to the SCLK input. The serial interface is
designed to allow the part to be interfaced to systems that
provide a serial clock that is synchronized to the serial data.
There are two types of serial operation: a read and a write.
Command words are used to distinguish between a read and a
write operation. These command words are given in Table 60.
Address auto-incrementing is possible in SPI mode.
Table 60. SPI Command Words
Write
Read
90h (1001 0000)
91h (1001 0001)
Write Operation
Figure 37 shows the timing diagram for a write operation to the
ADT7411. Data is clocked into the registers on the rising edge
of SCLK. When the CS line is high, the DIN and DOUT lines
are in three-state mode. Only when the CS goes from a high to a
low does the part accept any data on the DIN line. In SPI mode,
the address pointer register is capable of auto-incrementing to
the next register in the register map without having to load the
address pointer register each time. In Figure 37, the register
address portion of the diagram gives the first register that will
be written to. Subsequent data bytes will be written into sequen-
tial writable registers. Thus, after each data byte has been writ-
ten into a register, the address pointer register auto-increments
its value to the next available register. The address pointer
register will auto-increment from 00h to 3Fh and then loop
back to start over again at 00h.
Read Operation
Figure 38 to Figure 40 show the timing diagrams of correct read
operations. To read back from a register, first write to the add-
ress pointer register with the address to be read from. This
operation is shown in Figure 38. Figure 39 shows the procedure
for reading back a single byte of data. The read command is first
sent to the part during the first eight clock cycles, during the
following eight clock cycles the data contained in the register
selected by the address pointer register is output onto the
DOUT line. Data is output onto the DOUT line on the falling
edge of SCLK. Figure 40 shows the procedure when reading
data from two sequential registers.
Multiple data reads are possible in SPI interface mode as the
address pointer register is auto-incremental. The address
pointer register will auto-increment from 00h to 3Fh and will
loop back to start all over again at 00h when it reaches 3Fh.
SMBus/SPI INT/INT
The ADT7411 INT/INT output is an interrupt line for devices
that want to trade their ability to master for an extra pin. The
ADT7411 is a slave-only device and uses the SMBus/SPI
INT/INT to signal the host device that it wants to talk. The
SMBus/SPI INT/INT on the ADT7411 is used as an over/under
limit indicator.
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