u/IllustriousFan3350

Hi guys,

First time using a fuel gauge IC (BQ27621) with an ESP32 and a single 18650 cell — would appreciate a sanity check on my schematic!

Here's my reasoning for the key connections.

Reasoning:

GPOUT — connected to an ESP32 GPIO with a 10k pull-up resistor (open-drain output, as per datasheet)
BIN — pulled low, as the battery is embedded and not user-replaceable
VSS — tied to GND with a 0.47µF decoupling cap as recommended
SDA/SCL — connected to ESP32 I2C pins; added 1M resistors to GND to prevent floating when the ESP32 is off or on low power mode (section 11), plus 5.1k pull-ups on the lines
VBAT — connected to the positive battery terminal with a 1µF decoupling cap

spec sheet: https://www.ti.com/lit/ds/symlink/bq27621-g1.pdf?ts=1777134556819

Cheers!

u/IllustriousFan3350 — 23 days ago

▲ 10 r/PCB

Hi guys,

I'm currently working on implementing a fuel gauge and the cheapest options are from TI at around $0.30 — but most of them come in a 9-ball BGA (0.5mm pitch) . The next best option with visible, accessible pins is from Maxim at around $1.14.

Should I pay four times more to avoid the BGA?

What are people's real life experiences with BGA in production — yield, repairability, gotchas? Would you bite the bullet and pay more, or just go for the BGA?

Cheers!

reddit.com

u/IllustriousFan3350 — 27 days ago