LT3471

Hi chchaa ,

I am afraid you'll need to be more expressive in describing the condition.

Question: While the SW1 and SW2 are shorted to ground, do you still see +5V at Vin?

If yes, then your inductors L1, L3 are not correctly assembled or they are fake.

If no, then your +5V supply may not be adequate or the chip is assembled 180 degrees wrong way.

Cheers, heke

Hi heke,

Thank you very much for your prompt and insightful advice. I truly appreciate your support in helping me troubleshoot this issue.

I’d like to share the observations from my latest test:

1. After applying the 5V input voltage, the chip started to smoke. Once I disconnected the power supply, I used a multimeter in continuity mode and found a short between the Vin(+5V) and ground (GND).

2. I have double-checked the chip orientation, and it is correctly mounted — the pinout matches exactly with the datasheet.

   I’d greatly appreciate any further suggestions you might have.Below is my PCB layout.

The inductor used is FXL0420-6R8-M, with specifications: 6.8 μH, 2.4 A, ±20%, SMD 4.2 × 4.4 mm.Please note that due to a footprint mismatch, I had to solder the inductor using wires to connect it to the board, rather than mounting it directly.