LM5069: Large FET driving capabilities (MMIX1F520N075T2)

Nicolas CLOES

Part Number: LM5069

Dear TI Team,

I already implemented solutions using LM5069 for reasonable power levels (24V, 40A). I have now some requests for higher power designs.

What is the capability of the LM5069 to drive big FETs? I'm thinking about the Ixys MMIX1F520N075T2.

Do you think the LM5069 could drive two of them? What are the key points to take care while doing so? Any resources to help with the calculations?

Thanks,

Nicolas

over 2 years ago

0 Avishek Pal over 2 years ago

TI__Mastermind 30915 points

Hi Nicolas,

Welcome to E2E and thanks for your interest on LM5069.

LM5069 can drive two MMIX1F520N075T2. The MOSFET turn-off time after the short-circuit fault needs to be taken care of when the effective MOSFET C_GS is more.

Please fill-up the design calculator and share with us for review. The design calculator is available at https://www.ti.com/lit/zip/snvu050. If required, a PNP transistor based fast pull-down circuit can be incorporated to significantly reduce the turn-off time.

0 Nicolas CLOES over 2 years ago in reply to Avishek Pal

Prodigy 10 points

Hi Avishek,

Thank you for your quick answer and very useful information. Attached you will find the filled design calculator (very preliminary design). LM5069_Design_Calculator_REV_C_MMIX1F520N075T2_TI.xlsx

Can you confirm this pull-down circuit can do the job (found on another post here on the forum)? In this case, where should I connect the dv/dt control (between LM5069 and resistor or between resistor and FET)?

Best regards,

Nicolas

0 Avishek Pal over 2 years ago in reply to Nicolas CLOES

TI__Mastermind 30915 points

Hi Nicolas,

I will get back to you by Monday.

+1 Avishek Pal over 2 years ago in reply to Avishek Pal

TI__Mastermind 30915 points

Hi Nicolas,

Thanks for sharing the filled-up design calculator. Please see the edited one and let me know if there is any query. Cell F52 should be the MOSFET junction to ambient thermal resistance. I didn't find this parameter in the MMIX1F520N075T2 datasheet. Please confirm with the MOSFET manufacturer. This is a very important design parameter. Cell F54 should be the MOSFET R_DSON at the maximum steady-state MOSFET junction temperature calculated in cell F62.

LM5069_Design_Calculator_MMIX1F520N075T2_TI_Edited by TI.xlsx

Please see the below schematic regarding DVDT and the fast pull-down circuit.

0 Nicolas CLOES over 2 years ago in reply to Avishek Pal

Prodigy 10 points

Hi Avishek,

Everything is clear for me, thanks a lot for your support.

For you (or anyone interested) to know, MMIX1F520N075T2 is specially designed for very efficient heat transfert, as there is an electrically isolated metal pad for direct contact with a heatsink. Junction to ambient will then depend on the heatsink choice or design (Junction to Case and Case to Heatsink are specified in the datasheet, 0.23 °C/W).

Best regards,

Nicolas

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LM5069: Large FET driving capabilities (MMIX1F520N075T2)