SPV1040 IC Burns

MANIPILLAI · ‎2025-09-18

@TDK , @Peter BENSCH we are facing SPV1040 IC failure (burns) in the field, after around 3 months of installation, attached schematic and our solar Panel speciation Voc:4.55V, Vm:3.85V, ISC:1026mA, Im:950mA.
Battery spec - 9000mAh, 4.2V Lithium ion.

Peter BENSCH · ‎2025-09-19

Welcome @MANIPILLAI, to the community!

It looks like you based your design on the STEVAL-ISV012V1. However, if all components are assembled as shown in your schematics, you have at least one error: R35 is 82k in your design, which causes the SPV1040 to try to generate an output voltage of 34.79V (VCTRL is compared to 1.25V). So if you actually have 82k on the board, that could be the explanation and you should replace it with 820k.

Hope that helps?

Regards
/Peter

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MANIPILLAI · ‎2025-09-19

Thanks for your quick response.

sorry it's a typo error in schematic, actually we are using 820k in our assembled boards also all the other components are assembled as per schematic.

Peter BENSCH · ‎2025-09-19

OK, the next possible fault is the boost coil, whose maximum saturation current is somewhat low. It is possible that the peak current exceeds the saturation current limit when the solar panel is poorly lit, i.e. when the input voltage is low, causing the inductance to collapse and suddenly become a short circuit. You could therefore test a boost coil with a higher saturation current.

If this is not the cause, the defective SPV1040 would need to be analysed more closely to determine the possible causes.

Regards
/Peter

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MANIPILLAI · ‎2025-09-19

Thanks for your quick response.

we will test with replacing the boost coil, can you please suggest any spec for it.

regarding defective SPV1040, we found short with Lx and GND.

Peter BENSCH · ‎2025-09-19

The short between LX and GND confirms my suspicion that the boost coil may be undersized. Its magnetic field collapses while the boost transistor is switched on, causing a short circuit between the solar panel and GND, which will overload / kill the boost transistor.

I recommend a coil with a minimum saturation current of 4A, but this will probably be bulkier because the coil wire is thicker.

Regards
/Peter

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