• Hardware thermal shutdown (TSHUT)
– Can be configured to disable VOUT when triggered
– The threshold can be set from 105 to 135 °C with a 10 °C step.
• Firmware OVTP
– Can be configured to disable VOUT when triggered
– Can also be configured to force the receiver to send EPT packet when triggered
– The threshold can be set from 105 to 135 °C with 0.1 °C step.
• NTC OVTP
– Senses NTC voltage, usually used for coil temperature monitoring
– Can be configured to disable VOUT when triggered
– Can also be configured to force the receiver to send EPT packet when triggered
– The threshold can be set from 0 to 2.5 V.
5.9.1 Soft overvoltage protection (SOVP)
SOVP protects the device against excessive rectifier voltage. When VRECT rises above a set threshold, the
device will try to lower its value by connecting external power resistors (connected to IEXT pin) from VRECT to
ground through internal transistors. This approach should achieve lowering the rectifier voltage without losing
communication with the transmitter. Therefore, triggering this protection does not necessarily lead to regulation
failure or power transfer termination. The protection can also be configured to disable the output and/or force the
receiver to send EPT packet when triggered.
The SOVP can be set to either dynamic or static operation. In dynamic mode , when VRECT > VOUT SET +
SOVP threshold, IEXT switch will be turned-on.
In static mode , when VRECT > 12 V + SOVP threshold, IEXT switch will be turned-on.
The SOVP threshold is programmable from 2 V to 5 V in step sizes of 0.2 V. It can be set by STSW-WPSTUDIO
PC GUI tool or host controller via I
2
C. SOVP is released when VRECT < SOVP threshold - 1 V.
In dynamic mode, the SOVP threshold is output setting dependent:
• Output enabled: the threshold is set as output voltage + margin
• Output disabled: the threshold is set to 12 V + margin
In dynamic mode the user may accidentally trigger protection. As previously mentioned, the threshold is set
relative to the output voltage. When changing the output voltage setting, the SOVP threshold is adjusted
automatically. However, the regulation loop is quite slow and may not be fast enough to accommodate a large
voltage change. This might cause the rectifier voltage to temporarily exceed the SOVP threshold. Therefore, it is
advised to change the output voltage slowly (in multiple smaller steps).
Figure 17. SOVP Rx protection threshold setting
UM3154
Protections overview
UM3154 - Rev 2
page 18/81
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