TMP435
SBOS495A –MARCH 2010–REVISED APRIL 2010
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The TMP435 also has a THERM limit register for both
the local and the remote channels. These are 8-bit
registers 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.
Status Register
The TMP435 has a Status Register to report the state
of the temperature comparators. Table 4 shows the
Status Register bits. The Status Register is read-only
and is read by reading from pointer address 02h.
The BUSY bit reads as ‘1’ if the ADC is making a
conversion. It reads as ‘0’ if the ADC is not
converting.
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).
The OPEN bit reads as ‘1’ if the remote transistor
was detected as open since the last read of the
Status Register. The OPEN status is only detected
when the ADC attempts to convert
temperature.
a remote
The RTHRM bit reads as ‘1’ if the remote
temperature has exceeded the remote THERM limit
and remains greater than the remote THERM limit
less the value in the shared Hysteresis Register; see
Figure 20.
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.
The LTHRM bit reads as ‘1’ if the local temperature
has exceeded the local THERM limit and remains
greater than the local THERM limit less the value in
the shared Hysteresis Register; see Figure 20.
Table 4. TMP435 Status Register Format
TMP435 STATUS REGISTER (Read = 02h, Write = NA)
BIT #
BIT NAME
D7
BUSY
0(1)
D6
LHIGH
0
D5
LLOW
0
D4
RHIGH
0
D3
RLOW
0
D2
OPEN
0
D1
RTHRM
0
D0
LTHRM
0
POR VALUE
(1) The BUSY bit changes to ‘1’ almost immediately (<< 100ms) following power-up, as the TMP435 begins the first temperature conversion.
It is high whenever the TMP435 is converting a temperature reading.
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