SiC technology vs. silicon

AN3152

14/17

Doc ID 17056 Rev 1

4

SiC technology vs. silicon

When using very fast power MOSFETs, the use of very fast diodes is also necessary in

order to prevent failures. Unfortunately, due to the relatively slow recovery of silicon diodes,

(even ultra-fast silicon diodes) they cannot be used in this project. In order to meet the new

requirements, ST has developed and introduced a new family of diodes using the new

silicon carbide technology. Silicon carbide diodes are virtually free of recovery current, even

if, due to the charge and discharge of the parasitic capacitance, a peak current is still

present during commutation. But this peak value is very low compared to a silicon diode

using the same forward and breakdown voltage. These devices are the best choice for a

high-end solar application where performance is the primary target. A comparison between

SiC and silicon diodes has been performed in a side-by-side test between a silicon ultra-fast

diode and a SiC with the same forward parameters, and using a di/dt = 800 A/µs.

Table 2

provides the results of this comparison.

Figure 11 shows the recovery at I

power MOSFET if it is used on the converter prototype. In other words, silicon diodes cannot

be used in this type of design where the di/dt is very high (from 800 A/µs to 2000 A/µs).

Figure 11.

Table 2.

Parameter

STPCS1006D

STTH8L06D

1.12

1.2

1.12

0.9

26

293

3.7

9.9

13

44