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SBOS383C − DECEMBER 2006 − REVISED MAY 2008
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10
TEMPERATURE REGISTERS
The TMP411 has four 8-bit registers that hold temperature
measurement results. Both the local channel and the
remote channel have a high byte register that contains the
most significant bits (MSBs) of the temperature
analog-to-digital converter (ADC) result and a low byte
register that contains the least significant bits (LSBs) of the
temperature ADC result. The local channel high byte
address is 00h; the local channel low byte address is 15h.
The remote channel high byte is at address 01h; the
remote channel low byte address is 10h. These registers
are read-only and are updated by the ADC each time a
temperature measurement is completed.
The TMP411 contains circuitry to assure that a low byte
register read command returns data from the same ADC
conversion as the immediately preceding high byte read
command. This assurance remains valid only until another
register is read. For proper operation, the high byte of a
temperature register should be read first. The low byte
register should be read in the next read command. The low
byte register may be left unread if the LSBs are not
needed. Alternatively, the temperature registers may be
read as a 16-bit register by using a single two-byte read
command from address 00h for the local channel result o r
from address 01h for the remote channel result. The high
byte will be output first, followed by the low byte. Both bytes
of this read operation will be from the same ADC
conversion. The power-on reset value of both temperature
registers is 00h.
LIMIT REGISTERS
The TMP411 has 11 registers for setting comparator limits
for both the local and remote measurement channels.
These registers have read and write capability. The High
and Low Limit Registers for both channels span two
registers, as do the temperature registers. The local
temperature high limit is set by writing the high byte to
pointer address 0Bh and writing the low byte to pointer
address 16h, or by using a single two-byte write command
(high byte first) to pointer address 0Bh. The local
temperature high limit is obtained by reading the high byte
from pointer address 05h and the low byte from pointer
address 16h or by using a two-byte read command from
pointer address 05h. The power-on reset value of the local
temperature high limit is 55h/00h. The power-on reset
value of the local temperature high limit is 55h/00h (+85°C
in standard temperature mode; +21°C in extended
temperature mode).
Similarly, the local temperature low limit is set by writing
the high byte to pointer address 0Ch and writing the low
byte to pointer address 17h, or by using a single two-byte
write command to pointer address 0Ch. The local
temperature low limit is read by reading the high byte from
pointer address 06h and the low byte from pointer address
17h, or by using a two-byte read from pointer address 06h.
The power-on reset value of the local temperature low limit
register is 00h/00h (0°C in standard temperature mode;
−64°C in extended mode).
The remote temperature high limit is set by writing the high
byte to pointer address 0Dh and writing the low byte to
pointer address 13h, or by using a two-byte write
command to pointer address 0Dh. The remote
temperature high limit is obtained by reading the high byte
from pointer address 07h and the low byte from pointer
address 13h, or by using a two-byte read command from
pointer address 07h. The power-on reset value of the
Remote Temperature High Limit Register is 55h/00h
(+85°C in standard temperature mode; +21°C in extended
temperature mode).
The remote temperature low limit is set by writing the high
byte to pointer address 0Eh and writing the low byte to
pointer address 14h, or by using a two-byte write to pointer
address 0Eh. The remote temperature low limit is read by
reading the high byte from pointer address 08h and the low
byte from pointer address 14h, or by using a two-byte read
from pointer address 08h. The power-on reset value of the
Remote Temperature Low Limit Register is 00h/00h (0°C
in standard temperature mode; −64°C in extended mode).
The TMP411 also has a THERM limit register for both the
local and the remote channels. These registers are eight
bits and allow for THERM limits set to 1°C resolution. The
local channel THERM limit is set by writing to pointer
address 20h. The remote channel THERM limit is set by
writing to pointer address 19h. The local channel THERM
limit is obtained by reading from pointer address 20h; the
remote channel THERM limit is read by reading from
pointer address 19h. The power-on reset value of the
THERM limit registers is 55h (+85°C in standard
temperature mode; +21°C in extended temperature
mode). The THERM limit comparators also have
hysteresis. The hysteresis of both comparators is set by
writing to pointer address 21h. The hysteresis value is
obtained by reading from pointer address 21h. The value
in the Hysteresis Register is an unsigned number (always
positive). The power-on reset value of this register is 0Ah
(+10°C).
Whenever changing between standard and extended
temperature ranges, be aware that the temperatures
stored in the temperature limit registers are NOT
automatically reformatted to correspond to the new
temperature range format. These values must be
reprogrammed in the appropriate binary or extended
binary format.