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I need your help to try to repair a battery charger of a Black & Decker drill.

The charger is composed of two devices; one is a simple power supply, and the second one is the BMS. Unfortunately my father reversed the polarity on the input of the BMS.

As you can see in the image, in the BMS there is this small burned SOT89 component, connected immediately after the 20 V input. My assumption is that it is a 5 V voltage regulator but I can't find any information without the full part number, and most of the ICs on the PCB seem to be proprietary. The brand of this SMD recovered from the logo is Advanced Analog Circuits.

Can anybody help me please?

Battery charger

BMS PCB

SOT89 to be identified

ocrdu
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itseeder
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  • Buying another one is perhaps an option. You can then use it to figure out the function of the damaged device. Then repair the broken BMS, and you can sell it, or keep it as a spare. – Kuba hasn't forgotten Monica Aug 18 '22 at 22:33
  • Unfortunately is not so simple. I already have a spare one and they have different hardware revision with completely different logic and ICs. – itseeder Aug 18 '22 at 22:37
  • Perhaps you can try reverse engineering the schematic. Does not look like that large a circuit. Maybe then it becomes obvious what it's function is and a replacement could be chosen. – Unimportant Aug 18 '22 at 23:48
  • BMS IC are often custom and with strange brands. Even if you know what that IC is, it might be hard to find a place to purchase it. – Lundin Aug 19 '22 at 06:28

1 Answers1

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The manufacturer of this chip is Advanced Analogic Crcuits which was later bought by Skyworks.

Information beyond that is hard to find. There is a AAT3220 which has the same package. But the marking is not listed in the table, so it's probably a different device.

You can get a list of all datasheets for devices starting with AAT here. I've been going through quite a lot, but so far only the LDOs come in a SOT89 package.

I've found another LDO regulator by AAC, named AP2315, but that carries the markings E27E or E27F. But that opens another list of possible part numbers. The datasheet also mentions a BCD Semiconductor Manufacturing Limited. So that's another possible company to search for.

AHK* seems also to be a possible candidate for parts by AAC.

After going down the route of BCD Semiconductor Manufacturing Limited I found the following:

AS78LXX which has a marking of E78x with x from E to I depending on the output voltage. E being 5 V.

So that might be a hit, but sadly the marking in the picture is damaged.

This part is now sold under Diodes Inc. So there is another acquisition...

Arsenal
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