I have been trying to get a PowerShield working and recently tried to populate the board with an IFX007T instead of a BTN8982, the datasheets for the two (IFX, BTN) as well as a post in the original PowerShield thread seem to indicate that they are drop-in replacements for one another.
However, when I populated the PowerShield with the IFX chip, during the encoder alignment it draws all available power from the power supply while failing to turn the motor. Whereas with the BTN it draws around 3 amps and completes the alignment just fine.
They are two different boards so there is a chance that something else on the board is causing the problem, but from what I can tell there are no differences and no obvious shorts between pins or anything. So I am just curious if anyone has had any luck swapping out these chips for one another in one of their designs.
They are, indeed, one is the automotive version (expensive and high quality) and the IFX is the general use (cheap and lower quality).
Where did you get your mosfets?
May be the boards are a problem.
I’ve done this, and had no problem at all, but I acquired my chips from the official distributor, and used the exact same board for both.
There are too many variables here, different boards, probably different distributors / manufacturers of the chips. Just because it says IFX or BTN means nothing unless you got them from Mouser, DigiKey or straight from Infineon.
@Valentine, thanks for the quick response. It’s encouraging to know you have done this in the past.
The IFX chips were taken off of an Infineon BLDC-Shield that was purchased from DigiKey. The BTN chips were not from a particularly reputable source, which is why I was attempting to validate things with the IFX chips.
But thinking on it now maybe I wasn’t careful enough in the recovery step. Though the different board theory also seems like it could be the culprit.
Hmmm… that sounds actually like a good way to get the mosfets, if executed properly.
However the IFX have a low temperature threshold, unlike the BTN which are high temperature automotive version. The IFX may not be capable of reflowing twice (actually 3 times, counting the desoldering). Usually these silicon chips have very limited reflow temperature cycle with a very strict temperature profile. If you did not for example dry the chips in an oven for 24 hours before desoldering and resoldering, you may have cracked the epoxy, where the trapped moisture inside would damage the tiny wires on the silicon. That’s only one of the things that could go wrong.
Please read the following before attempting this type of surgery
@Valentine, thanks for the insights. I did not do the drying in the oven, so will definitely read through those assembly recommendations and then potentially give it another shot.
Oven drying for 24 hours or keeping your packages in a dry box is an absolute must when dealing with the thick ceramic epoxy of the high power modules else it cracks. Most people never do that because they are used to soldering small and thin components which are not really moisture sensitive and also the packages when hand soldered don’t overheat. Soldering the thick TO packages requires heating up the entire package for a long period of time to get it to wet nicely, especially if you use lead-based solder paste. Even touching with fingers will transfer moisture from your fingers into the dry package. Gloves, face mask, and metal tweezers only.