measurements match. When the measurements match, the channel output is released. Note that it is possible to

connect some device outputs together by shorting the OUTA or OUTB line.

8.2.1.2 Detailed Design Procedure

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 7-1 and Table 7-2. 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 output under the hot/cold thresholds is shown in Figure 8-2. 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.

8.2.1.3 Application Curves

Time (s)

Time (s)

OUTA

OUTB

Hysteresis

5°C, or 10°C

Hot threshold

Cold threshold

(Channel A)

(Channel B)

Figure 8-2. TMP390 Output With Hot/Cold Thresholds With Hysteresis

TMP390

SBOS904A – MAY 2019 – REVISED AUGUST 2020

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