Questions on Power « Jee Labs Talk

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Questions on Power

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rudivd

Hi all,
I have some questions regarding power on the Jnode USB (v.4), carrier board and ethercard... Right now I'm getting the complete setup powered from my laptop / desktop through USB. Weird thing is that if I plug in the ethercard the orange LiPo charge led is "on" (no LiPo connected). If I remove the Ethercard then it is off.... This is kinda weird to me I think. The host supplies a quite ok 4.95 V to the boards... If I supply 5.0 V to the board directly (no USB connected) the charge LED does not light..
Furthermore, I suspect that the power connector on the Carrier board is 5 V?? So if I want to use it I have to make sure that the voltage from the powersupply is <= 5V, right ?
Rudi.

Posted 07/06/2010 09:42:55
jcw

The charge light also comes on when there is no LiPo and the circuit draws more than just the JeeNode's 20..30 mA or so. It's a (slightly unfortunate) side-effect of using the charge chip for powering everything. This is normal.
The CarrIer Board PWR line is tied directly to the PWR line on the various plugs and cards, and the JeeNode. For use with a JeeNode USB, you'll need to take the MAX1555 charge chip into consideration, since PWR is connected to the BAT side. I'd say up to 5V, but it's probably fine up to 6V. With a plain JeeNode or a JeeSMD, PWR can go up to 13V. The JeeNodes and JeeSMD have an on-board low-dropout regulator, so they'll run at 3.3V internally as long as the PWR voltage is above 3.5V (roughly).

Posted 07/06/2010 10:54:24
lvdbor

Hi,
I have an JeeNode USB v3, and after reading I could (http://cafe.jeelabs.net/ref/pinouts/), I put 12v on the pwr line and it ran fine. But now it won't do anything when connected to USB anymore. The leds will blink a couple of times, but that's it. I need to attach power to the pwr pin to be able to connect with it. I guess I broke this MAX1555 chip right? Is it replaceable?
Best, Leon

Posted 29/10/2010 18:26:48
jcw

> after reading I could (http://cafe.jeelabs.net/ref/pinouts/), I put 12v on the pwr line
Whoa - that must indeed have fried the MAX1555 (I hope not your USB port!). If you don't use the LiPo charge capability, the what you could do is remove the MAX1555 and short IN to OUT to bypass this circuitry. You do lose some safety: don't put anything on PWR with such a modified JN, because you'll be attached directly to your computer's USB circuitry.
(BTW, I don't see how that page you mention suggests you can place 12V on a JN USB?)

Posted 29/10/2010 23:53:32
lvdbor

Hi Jean-Claude, Thank you for the answer. I'll try to take it off, and connect the in and out pins. Or maybe I shouldn't connect the in and out pins. If I don't then I'd always have to supply external power, but I can't make the mistake of frying my usb. Right?
As for how I got the impression that I could put 12v on the pwr of a JN USB: on the page is says: "PWR = input power, usually 3.5...13V", then below it shows a picture, with the text "JeeNode USB" in it. I guess I guessed wrong =/

Posted 30/10/2010 01:23:04
jcw
> maybe I shouldn't connect the in and out pins. If I don't then I'd always have to supply external power, but I can't make the mistake of frying my usb. Right?
Yes, leave it off to be safe. And yes, then you'll always need external power.
The "pinouts" page says:
```
        PWR = input power, usually 3.5 .. 13V
        (on JN USB: 3.5 .. 5V, or 4.2V with LiPo)
```
The second line is the one to watch out for...
Posted 30/10/2010 01:43:49
lvdbor

Okay, my bad. Well, the MAX chip is off and everything works "fine" =) Thanks for the help!

Posted 31/10/2010 09:56:32