Electronic – Placing multiple inductors (buck) close to each other on PCB

buckinductor

I have three buck converters on my PCB.

  1. 12V to 0.82V @ 25A –FP1308-R21-R, Fsw = 650 kHz, TPS548D21

  2. 12V to 1V @ 8A – IHLP2525CZERR47M01, Fsw = 1 MHz, TPS548A20

  3. 12V to 5V @ 3A – Inductor is XAL5030-332ME, 400 kHz (can be increased), TPS568215

Due to thermal issues and heatsink optimization, we need place all three of these inductors very close (3-5 mm) to each other.

All the inductors are shielded.

What will the inductor shielding effectiveness be? There is no specification on distance vs field.

Can we place all three inductors close to each other? If we can place them close together, what considerations do I need to take care of?

Added a PIC of this.enter image description here

Best Answer

What will the inductor shielding effectiveness be? There is no specification on distance vs field.

You can do a simple test - use 100 kHz (from a signal generator) applied to one inductor and see how much induced voltage is in another inductor when placed close to the driven inductor. I wouldn't want more than (say) 2% coupling (2% voltage induction). Rotate orientation to find least coupling and then design your PCB.