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

11

TMP464

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SBOS835 – MAY 2017

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Both local and remote temperature data use two bytes for data storage with a two's-complement format for

negative numbers. The high byte stores the temperature with 2°C resolution. The second or low byte stores the

decimal fraction value of the temperature and allows a higher measurement resolution, as shown in Table 1. The

measurement resolution for both the local and the remote channels is 0.0625°C.

7.3.2 Series Resistance Cancellation

Series resistance cancellation automatically eliminates the temperature error caused by the resistance of the

routing to the remote transistor or by the resistors of the optional external low-pass filter. A total up to 1-kΩ series

resistance can be cancelled by the TMP464 device, which eliminates the need for additional characterization and

temperature offset correction. See Figure 6 for details on the effects of series resistance on sensed remote

temperature error.

7.3.3 Differential Input Capacitance

The TMP464 device tolerates differential input capacitance of up to 1000 pF with minimal change in temperature

error. The effect of capacitance on the sensed remote temperature error is illustrated in Figure 7.

7.3.4 Sensor Fault

The TMP464 device can sense a fault at the D+ resulting from an incorrect diode connection. The TMP464

device can also sense an open circuit. Short-circuit conditions return a value of –256°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 the RxOP bit in the

Remote Channel Status register is set to 1.

When not using the remote sensor with the TMP464 device, the corresponding D+ and D– inputs must be

connected together to prevent meaningless fault warnings.

7.3.5

THERM Functions

Operation of the THERM (pin 10) and THERM2 (pin 11) interrupt pins are shown in Figure 12.

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

interrupts.

Figure 12. THERM and THERM2 Interrupt Operation