My application is single pulse for few mS, I think the desat function might not be able to use, could you please let me know the control signal timing for the inside MOSFET connected to DESAT pin?
Thanks,
Hailong Xu
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My application is single pulse for few mS, I think the desat function might not be able to use, could you please let me know the control signal timing for the inside MOSFET connected to DESAT pin?
Thanks,
Hailong Xu
Hello Hailong,
I'm an applications engineer in the high power drivers group.
DESAT is only operational during the on-state of the switching device (IGBT or MOSFET). The first level of timing is the blanking time, which is set by your external capacitor based on the equation given in Section 10.2.2.8. This is the first delay, which is typically within the nanoseconds range because of the time it takes for the IGBT/MOSFET to turn on. What kind of device are you using?
After the blanking time is complete, and the device has gone into desaturation then the DESAT fault is triggered as shown in the timing diagram of Figure 40. The timing specifications for DESAT are given in Table 7.10. The output will be driven low when DESAT is triggered based on the timing of t_desat(10%) to protect the system, which is defined as max 500ns. OUT is now held low. You are correct that the FAULT signal does take longer to transmit, at around 2us. However, you will not be able to turn on the device during this period of time after OUT has been pulled low, so the timing of t_desat(10%) should be sufficient to meet your timing requirements.
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Thanks,
Audrey