SNIS218A September 2019 – April 2020 TMP390-Q1
The resistor to ground values on the SETA input sets the TTRIP threshold of Channel A. The resistor to ground value on the SETB input sets the TTRIP threshold of Channel B as well as the THYST 5°C and 10°C options. TI recommends that the resistors at SETA and SETB have a 1% tolerance at room temperature. Each resistor can range from 1.05 KΩ to 909 KΩ, representing one of 48 unique values. The exact temperature thresholds and trip points are shown in Table 1 and Table 2. The pullup resistors should be at least 1 kΩ to minimize internal power dissipation. To get the correct threshold for resistor values, take care to minimize the board level capacitance and leakage at the SETA and SETB pins.
The waveform for the TMP390-Q1 output under the hot/cold thresholds is shown in Figure 10. The hysteresis can be set to 5°C, 10°C or 20°C. When the temperature exceeds the hot trip point threshold, OUTA goes low until the temperature drops below the hysteresis threshold. When the temperature drops below the cold trip threshold, OUTB goes low and returns high after the temperature rises above the hysteresis threshold. If the switch has already tripped and the temperature is in the hysteresis band, a POR event will cause the output to go high after the power is restored.