1EDI3020 For low voltage MOSFETs

[cluccitti]

Hello, for the purpose of driving power MOSFETs in a 48V high current inverter i am looking at the drivers 1EDI3020AS and 1EDI3030AS. My concerns are about overcurrent protection: is there a known way (reference design, app note, any suggestion...) to adapt DESAT or OCP features to the application? I think they have to be adapted because we cannot use a shunt (and so OCP) because of the current levels, and DESAT has too high a threshold. Power switch will be 80V high current TOLL MOSFETs, probably up to 4/5 paralleled.

Many Thanks in advance

Cesare

[AZIZ_HASSAN · Accepted solution]

Hi,

Thank you for posting your query at Infineon community.

Since, you have requested for the DESAT or OCP calculation application note , I have attached a link below which contains the detailed calculation as per your requirement.

https://www.infineon.com/dgdl/Infineon-EiceDRIVER-1EDI302xAS-1EDI303xAS-ApplicationNotes-v01_00-EN.p...

Regarding your concern related to usage of DESAT or OCP pin mainly for high current application, I suggest you to use one MOSFET leg (out of parallel MOSFET) and put shunt resistor to measure the current and you can calibrate in your microcontroller software based upon number of parallel switches. By this way you will measure only 1/4 current (if 4 parallel switches are there) and will solve your problem.

In same way you can use your DESAT also. Since the switches are connected in parallel, you can connect the DESAT circuit across any one parallel switch and do the calculations accordingly.

This is the one of the basic and proper way to use your DESAT protection when you connect your devices in parallel. It is not necessary to connect the external circuit across all the devices instead you can connect across any leg/switch to reduce the burden and the threshold value.

I hope the information will be  useful for you.

BR,

AZIZ HASSAN

[cluccitti]

Hi Aziz, many thanks for the reply. I found an interesting circuit at page 17 in the app note you linked that i think can solve the problem: it consists of using the OCP pin but measuring the voltage drop on the semiconductor instead of the shunt voltage. This can be useful although not very accurate and it has all the requirements i need because using a shunt is impossible for my application. 

Thank you

Cesare