93 lines
4.1 KiB
Markdown
93 lines
4.1 KiB
Markdown
v3
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changes:
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- more appropriate LED resistor values
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- change LED meaning
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- use only PDM mic
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- replace ESP32-S2 with ESP32 for PDM support, and better WLED support
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- make USB optional (only needed for debug)
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- add one I/O to port (allowing 3-line protocols like SPI or I2S)
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- change input capacitors (for manufacturability)
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tests:
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I tested the power supply to see if it capable of delivering 5A.
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It was, but only for a couple of seconds.
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It could provide 4A, but only for a 1-2 minutes.
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Then the temperature protection would kick in.
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There was no voltage drop, but stable 5V.
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Putting a tiny aluminium heat sink would make it last a bit more.
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What surprised me was that the SS510 diode D2 would get as warm as the TPS45460 voltage regulator, according to the infrared camera.
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I changed the configuration for the TPS45460 to switch it from economic to efficient, hoping it would get less hot:
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- inductor L1 from 6.8 uH to 2x6.8=13.6uH
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- CLK resistor R18 from 200k to 470k to change switching frequency from 484 kHz to ~200 kHz
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- AEC output capacitor was already large enough
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It could now deliver 5A for one minute, before D2 SS510 died (short).
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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).
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It could hold 3A for at least 30 minutes, stabilizing at around 140 degC.
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There the IR camera confirmed that the diode was warmer than the regulator.
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Conclusion: the regulator could be used with an average 3A output, with 4-5A peaks.
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To continuously provide more than 3A I need to change the switching diode to a 50WQ10FN.
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This has a much larger package (DPAK vs SMA) to better dissipate heat.
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It has also a lower voltages drop (770mV vs 880mV), using less power.
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But it is also much more expensive ($ 0.26 vs 0.05).
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I would still strongly recommend to also put a heat sink on it, and if possible with forced air flow.
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But this makes it more complicated to use, and not the intended usage of the board.
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This also explains why commercial 60V to 5V 5A modules have such a large heat sink.
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The board cannot be advertised as 5A capable anymore because it won't be able to hold it.
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Because of that, I will downgrade it to 3A.
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This way it can't damage itself.
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I will probably change the TPS45460 to a LMR16030.
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It has a 3A over-current protection, is simpler to use (fewer external components), and cheaper ($ 1.3 vs 0.7).
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I will still use the lower frequency higher efficiency configuration.
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v2
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fixes:
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- ESP antenna not surrounded by copper
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changes:
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- use larger barrier terminal for power ports to carry more current, clamp more wires, and allow wiring when the board is mounted in the enclosure
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- remove 5V jack to save space, 5V power can be provided by USB port, and to avoid plugging 8-60V into 5V port (frying all the electronics)
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- add board hole to fit in other enclosure version
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- use ESP32-S2-MINI instead of WROOM to save space and avoid Not Recommended for New Design part
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- use top spring terminal for LED data wires so they can be inserted when the board is mounted in the enclosure
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- add status LED and change LED meanings
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- complete re-layout, more compact
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- add I²S and PDM MEMS microphone (I²S is present because I did not test PDM yet)
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v1
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--
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fixes:
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- both pins of the spring terminals are connected
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changes:
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- use screw terminal for power input/output to support more current
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- add power input protection: PPTC and reverse polarity
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- 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
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- change DC-DC buck converter to TPS54560 for large input voltage (e.g. 48V power supply and batteries)
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issues: all the same as v0
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v0
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first prototype, with the bare features
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issues:
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- the case has actually other mounting holes
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- 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).
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- KF141R footprint is not long enough (not really an issue)
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- LED cables need to be stripped ~ 10 mm to fit it KF141R (minor inconvenience)
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