BQ25790 Interposer Board

YveltalGriffin

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As everyone knows, the silicon shortage has made it hard to get many different ICs for our hobby. I'm especially sad about the BQ25792 being unavailable for all of 2022. It's one of TI's latest li-ion chargers and combines the best features of the BQ24292i and BQ25895. 24V input, 5A charging for 1 to 4 cells, and integrated 16-bit ADC in a sleek HotRod QFN package.

bq25792.png


Since the BQ25792 is totally unavailable, a number of my projects using it are on hold. Luckily the chip-scale BGA cousin of the BQ25792, the BQ25790, is still available from AliExpress resellers. It uses the exact same silicon as the BQ25792 and is functionally identical. But it requires a high-density interconnect (HDI) PCB, which is very expensive.

So rather than converting all my designs to HDI and paying through the nose for each one, I have designed a 4x4mm HDI interposer PCB that adapts the BQ25790 to the BQ25792 footprint. This way I can use the BQ25790 in place of the BQ25792 on a standard low-cost PCB, keeping prototyping costs down in the long run.

1638804168122_hdi_interposer2d.png
1638804164796_hdi_interposer3d.png

Like I mentioned, HDI PCBs are expensive, so I'm posting to see if anyone else is interested in getting a few (or a lot) of these interposer boards, group buy style. If you are, please let me know by replying here or DMing me on Discord! (YveltalGriffin#8080) I'm happy to share design/pinout information if you want to integrate the interposer into your own custom board.
 

YveltalGriffin

First Wii U Trimmer
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Joined
Jun 7, 2016
Messages
292
Likes
1,050
Location
South Florida
Portables
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Welp, no sooner than I designed this PCB and posted about it, a Chinese supplier (stockpiler? hoarder?) got back to me and said they have BQ25792s in stock for $31 each. I'd rather buy 15 actual chips than a single panel of interposer PCBs for the same price. Desperate times indeed... :P
 
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