TMP435
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SBOS495A –MARCH 2010–REVISED APRIL 2010
Pointer Register
Limit Registers
Figure 14 shows the internal register structure of the
TMP435. The 8-bit Pointer Register is used to
address a given data register. The Pointer Register
identifies which of the data registers should respond
to a read or write command on the two-wire bus. This
register is set with every write command. A write
command must be issued to set the proper value in
The TMP435 has 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 Pointer Register before executing
a read
command. Table 3 describes the pointer address of
the registers available in the TMP435. The power-on
reset (POR) value of the Pointer Register is 00h
(0000 0000b).
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 (+85°C in standard temperature
mode; +21°C in extended temperature mode).
Temperature Registers
The TMP435 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 for the TMP435
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.
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 TMP435 contains circuitry to assure that a low
byte register read command returns data from the
same analog-to-digital (A/D) 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, or from
address 01h for the remote channel result (23h for
the second remote channel result). The high byte is
output first, followed by the low byte. Both bytes of
this read operation are from the same A/D
conversion. The power-on reset value of both
temperature registers is 00h.
The remote temperature high limit for the TMP435 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 for the TMP435 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).
Copyright © 2010, Texas Instruments Incorporated
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