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- The ground isolation of The upper device can only guarantee The dielectric withstand voltage - A floating power supply is required for series gate voltages - When connected in series, since The temperature coefficient of The on resistance is positive, in order to prevent thermal runaway it is necessary to consider sufficient derating - taking into account product variations - When used as A single high voltage switch in series it is recommended to implement appropriate voltage dividing measures such as inserting A large resistance in parallel - The switch timing must be matched to prevent destruction due to breakdown voltage
This is because the operating temperatures are different. For modules, the junction temperature Tj is 150°C and case temperatures Tc is 60°C, while for MOSFETs Tj is 175°C and Tc 25°C.
Although specific guidelines are not offered, please note that the wiring length from the device gate terminal to the gate drive circuit PC terminal has the greatest impact. The wiring inductance from the device source pin to the board ground pattern must also be taken into account.
Body diodes in SiC MOSFETs that consist of a pn junction feature a shorter minority carrier lifetime. This makes it difficult to see the accumulation effect of the minority carriers, enabling ultra-high-speed recovery performance (tens of ns) equivalent to SBDs. Also, the recovery time is constant and independent of forward injection current - similar to SBDs (if dI/dt is constant).
The bandgap of SiC is 3x that of silicon, resulting in a 3V larger rise voltage in the pn diode and consequently a relatively large forward voltage drop. However, since reverse conduction in the bridge circuit etc. is possible due to gate ON signal input during commutation, substantive steady-state loss should not be an issue.
Advantages of the trench design include 1) Lower ON resistance, 2) Smaller parasitic capacitance, and 3) Improved switching performance. One drawback, however, is reduced short-circuit tolerance due to the lower ON resistance.
Since the diode is connected internally, it is not possible to externally isolate characteristics. However, because the Vf of the SiC SBD is small, forward current within the normal operating range will flow only through the SiC SBD. Therefore, the If-Vf and reverse recovery characteristics can be considered a part of the SiC SBD characteristics.
The exposed metal sections (heat sink at back of package and bare metal section at the notch) are at the same potential as the drain. As a result, for products where the package includes a backside heat sink the creepage distance may be insufficient. Therefore, we ask that the user confirm the guidelines for creepage distance, taking into account the operating environment.
The operating check environment is compatible with 1) SIMetrix, 2) LTSpice, 3) OrCAD, and others using PSpice software. Hspice may not work since it does not support hyperbolic functions.