For proper operation, read the high byte of the temperature result first. Read the low byte register in the next

read command; if the LSBs are not needed, the register can be left unread. The power-on reset value of all

temperature registers is 00h.

8.1.3 Status Register

The status register reports the state of the temperature ADC, the temperature limit comparators, and the

connection to the remote sensor. Table 8-2 lists the status register bits. The status register is read-only and is

read by accessing pointer address 02h.

Table 8-2. Status Register Format

STATUS REGISTER (Read = 02h, Write = N/A)

BIT NUMBER

BIT NAME

FUNCTION

7

BUSY

= 1 when the ADC is converting

6

LHIGH(1)

= 1 when the local high temperature limit is tripped

5

LLOW(1)

= 1 when the local low temperature limit is tripped

4

RHIGH(1)

= 1 when the remote high temperature limit is tripped

3

RLOW(1)

= 1 when the remote low temperature limit is tripped

2

OPEN(1)

= 1 when the remote sensor is an open circuit

1

RTHRM

= 1 when the remote THERM limit is tripped

0

LTHRM

= 1 when the local THERM limit is tripped

(1)

These flags stay high until the status register is read or are reset by a POR when pin 10 is configured as ALERT. Only bit 2 (OPEN)

stays high until the status register is read or is reset by a POR when pin 10 is configured as THERM2.

The BUSY bit = 1 if the ADC is making a conversion. This bit is set to 0 if the ADC is not converting.

The LHIGH and LLOW bits indicate a local sensor overtemperature or undertemperature event, respectively.

The RHIGH and RLOW bits indicate a remote sensor overtemperature or undertemperature event, respectively.

The HIGH bit is set when the temperature exceeds the high limit in alert mode and therm mode, and the low

bit is set when the temperature goes below the low limit in alert mode. The OPEN bit indicates an open-circuit

condition on the remote sensor. When pin 10 is configured as the ALERT output, the five flags are NORed

together. If any of the five flags are high, the ALERT interrupt latch is set and the ALERT output goes low.

Reading the status register clears the five flags, provided that the condition that caused the setting of the flags

is not present anymore (that is, the value of the corresponding result register is within the limits, or the remote

sensor is connected properly and functional). The ALERT interrupt latch (and the ALERT pin correspondingly)

is not reset by reading the status register. The reset is done by the controller reading the temperature sensor

device address to service the interrupt, and only if the flags are reset and the condition that caused them to be

set is no longer present.

The RTHRM and LTHRM flags are set when the corresponding temperature exceeds the programmed THERM

limit. These flags are reset automatically when the temperature returns to within the limits. The THERM output

goes low in the case of overtemperature on either the local or remote channel, and goes high as soon as the

measurements are within the limits again. The THERM hysteresis register (21h) allows hysteresis to be added

so that the flag resets and the output goes high when the temperature returns to or goes below the limit value

minus the hysteresis value.

When pin 10 is configured as THERM2, only the high limits matter. The LHIGH and RHIGH flags are set if the

respective temperatures exceed the limit values, and the pin goes low to indicate the event. The LLOW and

RLOW flags have no effect on THERM2, and the output behaves the same way when configured as THERM.

8.1.4 Configuration Register

The configuration register sets the temperature range, the ALERT/ THERM modes, and controls the shutdown

mode. The configuration register is set by writing to pointer address 09h, and is read by reading from pointer

address 03h. Table 8-3 summarizes the bits of the configuration register.

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TMP9R01-SEP, TMP9R01-SP

SNIS238A – JULY 2025 – REVISED JULY 2026

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