Datasheet
AT30TSE752A/754A/758A [DATASHEET]
Atmel-8854G-DTS-AT30TSE752A-754A-758A-Datasheet_102014
18
After each temperature measurement and digital conversion is complete, the new temperature data is loaded into the
Temperature Register if the register is not currently being read. If a Read is in progress, then the previous temperature
data will be output. Accessing the Temperature Register continuously without waiting the maximum conversion time
(t
CONV
) for the selected resolution may prevent the device from properly updating the Temperature Register with new
temperature data.
In order to read the most recent temperature measurement data, the Pointer Register must be set or have been
previously set to 00h. If the Pointer Register has already been set to 00h, the Temperature Register can be read by
having the Master first initiate a Start condition followed by the AT30TSE752A/754A/758A device address byte
(1001AAA1 where “AAA” corresponds to the hard-wired A
2-0
address pins). After the AT30TSE752A/754A/758A has
received the proper address byte, the device will send an ACK to the Master. The Master can then read the upper byte of
the Temperature Register. After the upper byte of the Temperature Register has been clocked out of the
AT30TSE752A/754A/758A, the Master must send an ACK to indicate that it is ready for the lower byte of the temperature
data. The AT30TSE752A/754A/758A will then clock out the lower byte of the Temperature Register, after which the
Master must send a NACK to end the operation. When the AT30TSE752A/754A/758A receives the NACK, it will release
the SDA line so that the Master can send a Stop or repeated Start condition. If the Master does not send a NACK but
instead sends an ACK after the lower byte of the Temperature Register has been clocked out, then the device will repeat
the sequence by outputting new temperature data starting with the upper byte of the Temperature Register.
If 8-bit temperature resolution is satisfactory, then the lower byte of the Temperature Register does not need to be read.
In this case, the Master would send a NACK instead of an ACK after the upper byte of the Temperature Register has
been clocked out of the AT30TSE752A/754A/758A. When the AT30TSE752A/754A/758A receives the NACK, the device
will know that it should not send out the lower byte of the Temperature Register and will instead release the SDA line so
the Master can send a Stop or repeated Start condition.
The Temperature Register defaults to 0000h after device power-up or reset; therefore, the system should wait the
maximum conversion time (t
CONV
) for the selected resolution before attempting to read valid temperature data. If the
device is configured to power-up in the Shutdown mode, then the device will make a single temperature measurement
immediately after power-up so that valid temperature data can be output from the Temperature Register after the
maximum t
CONV
time. Since the Temperature Register is a Read-only Register, any attempts to write to the register will
be ignored, and the device will subsequently respond by sending a NACK back to the Master for any data bytes that are
sent.
Figure 6-2. Read Temperature Register — 16 Bits
Note: Assumes the Pointer Register was previously set to point to the Temperature Register.
Figure 6-3. Read Temperature Register — 8 Bits
Note: Assumes the Pointer Register was previously set to point to the Temperature Register.
SCK
SDA
Address Byte Temperature Register Upper Byte Temperature Register Lower Byte
Start
by
Master
ACK
from
Slave
ACK
from
Master
MSB
MSB
NACK
from
Master
Stop
by
Master
MSB
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
1 0 0 1 A A A 1 0 D15 D14 D13 D12 D11 D10 D9 D8 0 D7 D6 D5 D4 D3 D2 D1 D0 1
SCK
SDA
Address Byte Temperature Register Upper Byte
Start
by
Master
ACK
from
Slave
MSB MSB
NACK
from
Master
Stop
by
Master
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
1 0 0 1 A A A 1 0 D15 D14 D13 D12 D11 D10 D9 D8 1