TMP392

VDD

SETA

SETB

OUTA

OUTB

GND

Microprocessor

VCC

GND

78.7 kŸ

249 kŸ

10 kŸ

10 kŸ

0.1 µF

3.3 V

VDD = 3.0 V

Channel A Trip Temp = +90°C

and Hysteresis = 10°C

Channel B Trip Temp = 60°C

and Hysteresis = 10°C

13

TMP392

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SNIS216 – NOVEMBER 2019

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Typical Applications (continued)

8.2.2 TMP392 With 10°C Hysteresis

Figure 11 shows an example circuit for dual overtemperature protection using the TMP392. In this example, the

trip points are set at +60°C and +90°C with 10°C hysteresis. This circuit is useful in cases where a lower

overtemperature detection may be used to warn the application of rising system temperature and take software

corrective actions such as lowering the performance, while the higher overtemperature detection may be used to

start a fan to cool the system to a lower temperature.

Figure 11. TMP392 Example Circuit at +90°C and +60°C Thresholds With 10°C Hysteresis

8.2.2.1 Design Requirements

In this example, VDD can be

≥ 3 V. The output pins may be tied to a switch to control a fan or other analog

circuitry. Figure 11 uses 10-kΩ pullup resistors at the OUTA and OUTB outputs. Place a 0.1-µF bypass capacitor

close to the TMP392 device to reduce noise coupled from the power supply. If needed, the output of multiple

parts can be connected together.

8.2.2.2 Detailed Design Procedure

SETA sets the +90°C threshold using 78.7 kΩ. SETB sets the +60°C trip point and 10°C hysteresis using 249

kΩ. These values were determined using Table 1 and Table 2. These resistors should have maximum of 1%

tolerance at room temperature and 100 ppm/°C or less over the desired temperature range. A summary of the

resistor settings used in this example is shown in Table 3. See Table 1 and Table 2 for additional trip points and

hysteresis configurations.

The switching output of the TMP392 can be visualized with the output diagram shown in Figure 12. It is key to

notice that hysteresis is subtracted from both Channel A and Channel B threshold values. OUTA remains high

until the sensor reaches +90°C where the output goes low, and returns high after the temperature drops back

down to +80°C. OUTB remains high until the sensor reaches +60°C where the output goes low, and returns high

after the temperature drops back down to +50°C.

Table 3. Example Resistor Settings and Trip Points

CHANNEL

RESISTOR SETTING (kΩ)

HYSTERESIS (°C)

TRIP TEMPERATURE (°C)

SETA

78.7

10

+90

SETB

249

+60