4.8.3 Overtemperature protection (OVTP)
The temperature of the IC is continuously monitored by a temperature sensor. Excessive IC temperature may
indicate that either the operating power is too high, or an internal fault occurred. It should be considered that PCB
design may affect thermal performance as well. If the temperature exceeds a set threshold, power transfer is
terminated, and an OVTP interrupt is generated by the transmitter. The threshold is configurable in the GUI and
can be set in a range of 0 to 151 °C.
Figure 19. OVTP settings
4.8.4 NTC
An external NTC can be used to further monitor the operational temperature of the board. The user may choose a
component/board region to be monitored by placing the NTC on it/nearby, although monitoring the transmitting
coil is presumably the most common practice.
Together with a pull-up resistor, the NTC forms a voltage divider, which is connected to the STWBC86 NTC pin.
The NTC pin is 1.98 V tolerant, although an internal ADC supports only up to 1.5 V NTC voltage reading.
Therefore, it is recommended to design the voltage divider to reach the (low) NTC threshold at the highest
allowed temperature, while leaving a large enough margin for accurate temperature monitoring (the NTC voltage
should be kept below 1.5 V).
UM3161
Protections overview
UM3161 - Rev 1
page 19/78
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