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Revision B

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@slintak slintak released this 14 Sep 09:46
· 29 commits to main since this release
revB
7a42282

This is the second manufactured revision of the LinHT PCB, tagged as revB for reference and documentation.

Revision B is a major step forward from revA: it introduces the complete RF transmit chain, USB-C charging, GNSS, and proper power management. Several prototypes were manufactured and tested successfully.

⚠️ Important: While revB is functional and was used for extensive testing, we do not recommend manufacturing this revision. Testing revealed several issues that are corrected in Revision C.

What's new in revB

  • RF power amplifier (GRF5604) with SKY13330-397LF RF switch and two PE4312C-Z digital step attenuators in the RF input path.
  • USB-C battery charging based on BQ25792, including a battery PPTC fuse and thermistor interface.
  • GNSS receiver (Quectel LG77L) with an on-board chip antenna.
  • New audio codec TLV320AIC3100 (replacing the WM8960) with a dedicated 1.8 V I/O supply.
  • ATtiny826 power-management controller and a new 5 V converter (TPS565242).
  • Panelized fabrication outputs compliant with PCBWay and JLCPCB.

Known issues in revB

  • The side button voltage domains are not isolated — the button signal drives the 1.8 V SoM input directly.
  • The audio codec reset input is not connected to the SoM, so the codec cannot be reset from software.
  • The 12.288 MHz audio oscillator and codec MCLK arrangement proved problematic.
  • The on-board GNSS chip antenna underperforms; an external antenna connector is needed.
  • Some inductors are obsolete and hard to source.
  • Small ground-connected footprints lack thermal relief, making hand soldering difficult.

All of the above are addressed in Revision C.

Purpose of this release

This tag preserves the exact design state that was manufactured and tested, and documents what was learned from it.

What's Changed

  • Revision B -- first iteration by @slintak in #39
  • Add GNSS supoprt (LG77L module) by @slintak in #40
  • Add PPTC fuse to the battery by @slintak in #41
  • Add high-side MOSFET switch for GRF5604 V_EN inputs by @slintak in #42
  • Update README with more up-do-date info by @slintak in #43
  • Panelize PCB before making fabrication files by @slintak in #44

Full Changelog: revA...revB

Contributors

slintak
Assets 2
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