8.2.1.2 Detailed Design Procedure

The resistor to ground values on the SETA input sets the T_TRIP threshold of Channel A. The resistor to ground value on the SETB input sets the T_TRIP threshold of Channel B—as well as the T_HYST 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 TMP392 output for hot/warm 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 exceeds the warm trip threshold, OUTB goes low and returns high after the temperature drops below 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.