Update PCB Stackup to 2 Layers
Thought for 15 sec
Yes, Senhor Vasquez — it is possible, but you need two resistors and must break the existing direct FB-to-3.3 V connection. Adding only one resistor will not fix it.
For the adjustable TPS62827:
A suitable 1% resistor pair is:
- R_TOP = 453 kΩ: output to FB
- R_BOTTOM = 100 kΩ: FB to GND
This produces approximately:
That is suitable for a nominal 3.3 V rail.
Required modification
Text
3.3 V output ── 453 kΩ ──┐ ├── TPS62827 FB GND ────────── 100 kΩ ───┘
Procedure:
- Completely disconnect USB and the LiPo.
- Locate the PCB trace directly connecting U6 FB pin 3 to the 3.3 V output.
- Carefully cut that trace and confirm with a multimeter that FB is no longer shorted to the output.
- Solder 453 kΩ between the 3.3 V output and FB.
- Solder 100 kΩ between FB and GND.
- Keep both resistors and wires extremely close to U6; FB is sensitive to switching noise.
- Check for shorts under magnification.
- Initially power the board from a current-limited bench supply or USB current limiter, without the battery.
- Measure the output before allowing the ESP32-S3 and other loads to run. Expect approximately 3.3 V.
- U6 is a tiny 1.5 mm VSON package, so soldering directly to FB pin 3 is difficult.
- If the FB trace cannot be isolated cleanly, replacing the IC with TPS6282533DMQR may be safer.
- Do not power the board until the modification is complete. With FB directly connected to the output, the adjustable part will attempt to regulate near 0.6 V, not 3.3 V.
- Use 1% resistors. Avoid long jumper wires around the SW pin and inductor because those carry noisy switching signals.
Document and check mod
Show solder points
Calculate resistor options
Create rework guide
Check replacement option
