50

60

70

80

90

100

ALERT

THERM Limit

THERM Limit - Hysteresis

High Temperature Limit

THERM

110

120

130

140

150

Temperature Conversion Complete

Time

Measured

Temperature

ALERT output

serviced by master

50

60

70

80

90

100

THERM2

THERM Limit

THERM Limit - Hysteresis

THERM

110

120

130

140

150

Temperature Conversion Complete

Time

Measured

Temperature

THERM2 Limit

THERM2 Limit - Hysteresis

13

TMP461-SP

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SBOS876B – SEPTEMBER 2017 – REVISED FEBRUARY 2020

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7.3.5 Sensor Fault

The TMP461-SP device can sense a fault at the D+ input resulting from an incorrect diode connection. The

TMP461-SP device can also sense an open circuit. Short-circuit conditions return a value of –64°C. The

detection circuitry consists of a voltage comparator that trips when the voltage at D+ exceeds (V+) – 0.3 V

(typical). The comparator output is continuously checked during a conversion. If a fault is detected, then OPEN

(bit 2) in the status register is set to 1.

When not using the remote sensor with the TMP461-SP device, D+ must be connected to D– or GND to prevent

meaningless fault warnings.

7.3.6

ALERT and THERM Functions

Operation of the ALERT (pin 7) and THERM (pin 4) interrupts is shown in Figure 13. Operation of the THERM

(pin 4) and THERM2 (pin 7) interrupts is shown in Figure 14. The ALERT and THERM pin setting is determined

by bit 5 of the configuration register.

The hysteresis value is stored in the THERM hysteresis register and applies to both the THERM and THERM2

interrupts. The value of the CONAL[2:0] bits in the consecutive ALERT register (see Table 5) determines the

number of limit violations before the ALERT pin is tripped. The default value is 000b and corresponds to one

violation, 001b programs two consecutive violations, 011b programs three consecutive violations, and 111b

programs four consecutive violations. The CONAL[2:0] bits provide additional filtering for the ALERT pin state.

Figure 13. ALERT and THERM Interrupt Operation

Figure 14. THERM and THERM2 Interrupt Operation

7.4 Device Functional Modes

7.4.1 Shutdown Mode (SD)

The TMP461-SP shutdown mode enables the user to save maximum power by shutting down all device circuitry

other than the serial interface, and reducing current consumption to typically less than 3 μA; see Figure 10

(Shutdown Quiescent Current vs Supply Voltage). Shutdown mode is enabled when the SD bit (bit 6) of the

configuration register is high; the device shuts down after the current conversion is finished. When the SD bit is

low, the device maintains a continuous-conversion state.