Powering the C2 - MicroUSB Vs Barrel Jack

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RChadwick
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Powering the C2 - MicroUSB Vs Barrel Jack

Unread post by RChadwick » Fri Jan 04, 2019 6:12 am

I have a C2 paired with a 4TB USB drive and wireless Wifi/Bluetooth adapters, and want to power everything by the USB OTG connector. I understand there are lots of crappy cables and power adapters, but I want to use this in more of a portable application, and want the versatility of running from USB (Which is everywhere). I have a number of thick USB cables with little voltage drop, and 3 to 4 Amp (Measured, I don't trust labels) power adapters and battery packs. I found everything works fine with certain power adapters, but with others the HD isn't recognized. I haven't checked anything on a scope yet, but I'm assuming the power adapters that don't work are either full of nasty ripple, or maybe rated just slightly below what everything needs to start up. I took my setup apart to add a RTC and a needed fan, and was looking at the schematic to see what I could do. As the HD, and to a lesser degree the C2, require relatively low current with high spikes, my ideas so far:

1) Put a 0 Ohm at R10. I haven't looked up U6 yet (The NCP372), but I'm assuming it may be some overvoltage protection.
2) Put a 100uF cap and a pF cap in parallel with C114 (I believe it's the cap at the USB OTG connector)
3) Put a 47uF Cap and a pF cap in parallel with C102A/B or C103A/B (USB Connectors)
4) Make a barrel to Female MicroUSB adapter, and hope I don't lose it.

As I'm not familiar with why the Engineer(s) made certain choices, I'm looking for feedback before blindly moving forward.
Thanks!

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odroid
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Re: Powering the C2 - MicroUSB Vs Barrel Jack

Unread post by odroid » Fri Jan 04, 2019 9:31 am

The USB OTG power path is not efficient due to the host mode power switch and other components.
So you have to consider using the DC barrel jack to save more than 1 Watt.
https://wiki.odroid.com/odroid-c2/hardw ... wer_enable

If your power supply has a type-A USB host port, you can use a USB-Barrel power cable something like this.
https://www.hardkernel.com/shop/usb-dc- ... 2-5x0-8mm/

And measure the voltage on 5V rails of the 40pin header to make sure it is always higher than 4.7Volt when the USB HDD is spinning.
https://wiki.odroid.com/odroid-c2/hardw ... _2x20_pins

RChadwick
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Re: Powering the C2 - MicroUSB Vs Barrel Jack

Unread post by RChadwick » Fri Jan 04, 2019 3:41 pm

Thanks for your response!

I'm worried about losing that barrel connector cable. As it has worked fine in the past, I'd really like to power it through the USB port. What can I do to minimize losses? I looked up that NCP372, and it is an overvoltage cutoff switch. I'm guessing the spot at R10 was designed to bypass that? As I'm not using the barrel connector, the NCP372 wouldn't offer me much value. Are there other spots to look at? I haven't looked close yet, but is there a possibility to cut the +5V line at the MicroUSB connector, and run a wire to the center connector of the barrel connector? Would I even need to cut the trace?

Also, I'm a little confused about J1. If it's left connected while being powered by the barrel connector, the warning is that the C2 will draw more current and get hot. Is that the MOSFETs in the NCP372? Or something else?

Thanks again!

RChadwick
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Re: Powering the C2 - MicroUSB Vs Barrel Jack

Unread post by RChadwick » Sun Jan 06, 2019 1:18 am

Nevermind, I looked at the schematics closer. I think I was mixing up J1 and J4. It appears J1 makes a direct connection between the barrel jack and the MicroUSB port, and it appears the NCP372 doesn't need to be disabled.
Thanks again for your help!

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