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# About the calculation of the drain current of IAUC120N06S5N017 at 85°C

Level 1
Level 1

HI.

As shown in the figure below, I would like to know how the 30A current is calculated for the IAUC120N06S5N017 at T a=85 °C, VGS=10 V,RthJA on 2s2p2,4)? Thank you.

1 Solution

# Re: About the calculation of the drain current of IAUC120N06S5N017 at 85°C

Moderator
Moderator

Hi,

Usually for practical considerations we take Tj to be 150C.

Hence recalculating Id for this Tj comes to be around 32A which can be approximated to 30A.

Regards,
Abhilash P

4 Replies

# Re: About the calculation of the drain current of IAUC120N06S5N017 at 85°C

Moderator
Moderator

Hi,

Thank you for posting on the Infineon community.

The Id = 30A at Ta = 85C is calculated as below,

Step 1: Calculate Ptot at Ta = 85C

Ptot = (Tj - Ta ) / Rthja
=  (448.15 - 358.15)/23.3
= 3.862W
(Here Tj is 175C and Ta is 85C which is converted to Kelvin scale since Rthja is in K/W)

Step2: From Ptot we calculate Id

Ptot = Id^2 * Rdson

Id = sqrt ( (Ptot / Rdson) )
=  sqrt (( 3.86 / 2.5m))
=  39A
= approximately equal to 30A ( this is verified by practical measurements )

Regards,
Abhilash P

# Re: About the calculation of the drain current of IAUC120N06S5N017 at 85°C

Level 1
Level 1

HI. Abhilash_P .

According to your reply, the final result is 39A is approximately equal to 30A, the error of this approximation is a bit too large, right?The RDS of MOS tube is compensated according to 2.5mΩ, according to the curve of Figure 8 Typ. drain-source on-state resistance in the manual. The TJ used for the calculation is calculated according to the 175 ℃? Or according to 150 ℃ or other allowances with a certain margin? If TJ needs to leave a margin, what is the approximate margin?

# Re: About the calculation of the drain current of IAUC120N06S5N017 at 85°C

Moderator
Moderator

Hi,

Usually for practical considerations we take Tj to be 150C.

Hence recalculating Id for this Tj comes to be around 32A which can be approximated to 30A.

Regards,
Abhilash P

Level 1
Level 1