SLUAB11 November 2025 AMC23C12-Q1 , TMCS1126-Q1 , UCC21750-Q1
All three analyzed short-circuit protection methods are able to turn-off the SiC MOSFET under a SCT 1 condition safely. However, there are differences between the presented designs.
Table 5-2 lists a comparison of short-circuit protection methods. Among the evaluated methods, the shunt-based design stands out in terms of response time and accuracy. However, the limitation of this method is the highest overshoot of the drain-source voltage in the hard turn-off event. This issue can be mitigated by optimizing the PCB layout to minimize the stray inductance, allowing the SiC MOSFETs to operate at higher turn-off speeds without excessive overshoots in the drain-source voltage.
The Hall-effect sensor-based method meets the typical requirements for response time and accuracy, and it has lower power loss compared with shunt-based solution. However, basically hall-effect sensor is more susceptible in case of high diSC/dt during short-circuit events, which makes the PCB layout critical.
The desaturation-based protection incorporates a soft turn-off feature, which helps to gradually switch off the short-circuit current, significantly reducing the drain-source voltage overshoot. This relaxes the PCB design constraints which allows for higher stray inductance circuits, and also allows SiC MOSFETs to operate at maximum switching speed, minimizing energy losses during normal operation. However, the main limitation of the desaturation method is the relatively longer response time during SCT 1 faults. Design optimizations are necessary to lower this response time to maintain a safe turn-off in case of a short-circuit event.
| Parameter | Shunt | Hall Effect | Desaturation+ Soft Turn-Off |
|---|---|---|---|
| Response time | 380ns | 820ns | 1.55μs |
| Accuracy | ±3.4% | ±10% | Not applicable |
| Losses at 20A | 0.4W | 0.28W | Negligible |
| Overshoot | 1190V | 1090V | 940V |
In summary, these three options have their own benefits and limitation in different aspects.
Therefore, these three solutions are suitable for different scenarios, depending on the customer's requirement. Shunt-based method is particularly suitable for situations that require high response speed and accuracy. Hall-effect-based method is particularly suitable for situations that require lower losses and also current values for redundant software protection. Desaturation-based method is particularly good for situations that require lower voltage overshoot and easy PCB layout.