External 5.35 power supply?

[Randy Merkel]

I have some confusion over using an external power supply via the KEYSWITCH_POWER header (Hacks) and the 5.00v vs 5.35b power supply (Connection-options).

I want to use the hard key switch and an external power supply.Does the above mean that if I adjust my RS-15-5 power supply to 5.35v I should not short the voltage drop diode?

Thanks!

-- Randy

[oscarv]

Randy,

Unless the Pi 4 is designed differently from the Pi 3, the reason for the 5.35V (at least 5.1V) of the Pi's recommended power supply is in the circuitry from the Pi's onboard voltage regular. It is just not very good.

If you feed power in to the PiDP's 5V connector, you should not need it, and 5.0000V should be OK. Still, 5.1 or 5.2V is better (almost all Pi power supplies now deliver it anyway). You can then indeed short that voltage drop diode, the LEDs will burn a bit brighter for it.

BUT! Do make sure you add a wire from the keyswitch to close to the Pi's 40 pin connector. I designed the PiDP PCB in the Pi 2 times, and never thought the traces needed to carry this much current. The Pi 4 is power hungry... so running the power just over the PCB traces is marginal. With 5.35V you'll still be OK, with 5.0000V maybe not. There have been postings about this issue in the group.

Feel free to experiment, no risk of damage.

Kind regards,

Oscar

(not quite an electrical engineer, as it turned out...)

[Randy Merkel]

Thanks Oscar,

By "keyswitch to close to the Pi's 40 pin connector" do you mean "keyswitch close to the PI's 40 pin connector" I assume the later. I'll give it a try this weekend!

Randy

(a surly firmware engineer ;)

[Tim Boan]

With a well regulated external supply running at 5.15V the Pi4b was throwing a

low voltage alert. Adjusted the supply to 5.35V and it's been trucking along

fine. There is note inthe Pi4 manual that states a supply voltage of 5.35V

is desired, and the Pi4 wall warts typically supply the increased voltage.

Tim Boan

Virus-free.www.avast.com

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[Randy Merkel]

Hum... my official PI power supply says 5.1v on the brick, specs say 5v, but I'm seeing 4.7 V to 5.25 V here (https://raspberrypi.stackexchange.com/questions/99961/powering-the-pi-4-safe-voltage-levels-and-current-requirements).

Been running 2.11bsd for a few hours the the PI is more than toasty warm. Maybe a heatsync and/or fan?

[andy]

even a tiny fan on a Pi4 will help a lot :-)

[Randy Merkel]

Ordered a set of heat synchs to start, still thinking of adding a fan … later.

[Tim Boan]

There is a 5 VDC heatsink/fan combo that works great. Will run off the 5 VDC GPIO pin.

I speak from experience with this setup!!

Tim Boan

Virus-free.www.avast.com

To view this discussion on the web visit https://groups.google.com/d/msgid/pidp-11/77331d35-db89-40f5-9ed2-2b4865f2a284n%40googlegroups.com.

[Tim Boan]

GeeekPi Raspberry Pi 4 Aluminum Heatsink with PWM Controllable Fan, Raspberry Pi 4 Armor Lite Heatsink with PWM Speed Control Fan for Raspberry Pi 4 M

$10!!

Tim Boan

Virus-free.www.avast.com

On Fri, Mar 17, 2023 at 9:37 PM Randy Merkel <slowyb...@gmail.com> wrote:

To view this discussion on the web visit https://groups.google.com/d/msgid/pidp-11/77331d35-db89-40f5-9ed2-2b4865f2a284n%40googlegroups.com.