- I ordered the prototype in yellow, and while generally I don't like this color, here it suits the RJ45 port and other
black connectors.
- I feared the high screw terminal would be in the way of the cable to the spring terminals, but actually this is not an issue
issues:
- the ESP32-MINI-1U uses x.FL IPEX3/MHC3 antenna connector, instead of the classical u.FL MHC1 used by the ESP32-WROOM. IPEX3 pigtails are hard to find though. The ESP32-MINI-1U comes with a PCB antenna, which would avoid the issue, but it requires standard assembly, which the ESP32-MINI-1U does not.
- change buck voltage regulator to LMR16030, limiting to 3A output, since the board can't dissipate the heat generated by 5A buck (even in highest efficiency)
I tested the power supply to see if it capable of delivering 5A.
It was, but only for a couple of seconds.
It could provide 4A, but only for a 1-2 minutes.
Then the temperature protection would kick in.
There was no voltage drop, but stable 5V.
Putting a tiny aluminium heat sink would make it last a bit more.
What surprised me was that the SS510 diode D2 would get as warm as the TPS45460 voltage regulator, according to the infrared camera.
I changed the configuration for the TPS45460 to switch it from economic to efficient, hoping it would get less hot:
- inductor L1 from 6.8 uH to 2x6.8=13.6uH
- CLK resistor R18 from 200k to 470k to change switching frequency from 484 kHz to ~200 kHz
- AEC output capacitor was already large enough
It could now deliver 5A for one minute, before D2 SS510 died (short).
After changing the diode, it could deliver 4A for 5 minutes (without additional active/passive cooling), before the inductor desoldered from the board (the solder melted).
It could hold 3A for at least 30 minutes, stabilizing at around 140 degC.
There the IR camera confirmed that the diode was warmer than the regulator.
Conclusion: the regulator could be used with an average 3A output, with 4-5A peaks.
To continuously provide more than 3A I need to change the switching diode to a 50WQ10FN.
This has a much larger package (DPAK vs SMA) to better dissipate heat.
It has also a lower voltages drop (770mV vs 880mV), using less power.
But it is also much more expensive ($ 0.26 vs 0.05).
I would still strongly recommend to also put a heat sink on it, and if possible with forced air flow.
But this makes it more complicated to use, and not the intended usage of the board.
This also explains why commercial 60V to 5V 5A modules have such a large heat sink.
The board cannot be advertised as 5A capable anymore because it won't be able to hold it.
Because of that, I will downgrade it to 3A.
This way it can't damage itself.
I will probably change the TPS45460 to a LMR16030.
It has a 3A over-current protection, is simpler to use (fewer external components), and cheaper ($ 1.3 vs 0.7).
I will still use the lower frequency higher efficiency configuration.
- DMX RX is connected to DMX TX through R7+R11. I wanted to both activated the LED, but did not think of the interconnection. Just remove R7 to light on TX activity, or R11 for RX activity.
- add switch configure DMX512 line termination (loop back to D2 so the XLR chain can continue, end using a termination resistor, or continue forwarding to other port
- change DC-DC buck converter to TPS54560 for large input voltage (e.g. 48V power supply and batteries)
- WiFi does not work because of missing [copper clearance around the antenna](https://espressif.com/sites/default/files/documentation/esp32-s2_hardware_design_guidelines_en.pdf).
- KF141R footprint is not long enough (not really an issue)
- LED cables need to be stripped ~ 10 mm to fit it KF141R (minor inconvenience)