TMP435

SBOS495A – MARCH 2010 – REVISED APRIL 2010

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The TMP435 also has a THERM limit register for both

Status Register

the local and the remote channels. These are 8-bit

The TMP435 has a Status Register to report the state

registers and allow for THERM limits set to 1°C

of the temperature comparators. Table 4 shows the

resolution. The local channel THERM limit is set by

Status Register bits. The Status Register is read-only

writing to pointer address 20h. The remote channel

and is read by reading from pointer address 02h.

THERM limit is set by writing to pointer address 19h.

The BUSY bit reads as ‘1’ if the ADC is making a

The local channel THERM limit is obtained by reading

conversion. It reads as ‘0’ if the ADC is not

from pointer address 20h; the remote channel

converting.

THERM limit is read by reading from pointer address

19h. The power-on reset value of the THERM limit

The OPEN bit reads as ‘1’ if the remote transistor

registers is 55h (+85°C in standard temperature

was detected as open since the last read of the

mode; +21°C in extended temperature mode). The

Status Register. The OPEN status is only detected

THERM limit comparators also have hysteresis. The

when the ADC attempts to convert a remote

hysteresis of both comparators is set by writing to

temperature.

pointer address 21h. The hysteresis value is obtained

The

RTHRM

bit

reads

as

‘1’

if

the

remote

by reading from pointer address 21h. The value in the

temperature has exceeded the remote THERM limit

Hysteresis Register is an unsigned number (always

and remains greater than the remote THERM limit

positive). The power-on reset value of this register is

less the value in the shared Hysteresis Register; see

0Ah (+10°C).

Figure 20.

Whenever changing between standard and extended

The LTHRM bit reads as ‘1’ if the local temperature

temperature ranges, be aware that the temperatures

has exceeded the local THERM limit and remains

stored in the temperature limit registers are NOT

greater than the local THERM limit less the value in

automatically reformatted to correspond to the new

the shared Hysteresis Register; see Figure 20.

temperature range format. These values must be

reprogrammed in the appropriate binary or extended

binary format.

Table 4. TMP435 Status Register Format

TMP435 STATUS REGISTER (Read = 02h, Write = NA)

BIT #

D7

D6

D5

D4

D3

D2

D1

D0

BIT NAME

BUSY

LHIGH

LLOW

RHIGH

RLOW

OPEN

RTHRM

LTHRM

POR VALUE

0

0

0

0

0

0

0

(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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