Hi,
The datasheet for the Carambola2 says that it draws 0.5W, but for a new design I need to know what the peak current requirement is for the 3.3v power supply.

I've got a design here with a 600mA limit but the device reboots shortly after enabling wifi, and I suspect that the power supply is shutting down.

Can somebody post some specifics on the 3.3v power requirements?

Thanks,

dean

You could test using the USB power of your computer, normally it is not more than 500 mA. If it works with the USB power and not with your power supply, maybe you have a problem with your power supply.

Also, do you have something connected to the Carambola2 ? If yes, try with nothing connected and if it works, try to find what is the peripherals that creates the problem.

This is without any peripherals (no ethernet), just trying to boot and enable wifi.

I replaced the 600mA rated 3.3v power supply with a 1A capable supply and it boots and wifi works and is stable.

I see peak current draw on the 5v of 452mA (or 2.26W), so it seems the 0.5W rating on the datasheet is not a peak rating...

I did notice that the reference motherboard has a switching supply that appears to be rated for 2A.

Hi,
I have the same problem. I have Carambole2 module (not dev board). it doesnot even respond when it is on 3.23V. it strictly needs 3.25V+. It restarts when tries to make wireless up. I used a 36V-10A adjustable power supply. I configured the power supply as Constant Voltage mode and V=3.5V (that way i have 3.3V on Carambola2). On this mode, curent depends on how much carambola derives. It starts without wifi. if i enable wifi, it restarts repeatedly. Do you have any other idea, beacuse power supply can supply up to 10A? Then I gave 4.5V instead of 3.3V and wifi was on but there was a lot of heat, as well. I read current as 210mA. I've just wired all the ground pins and 3.3V pins and TX/RX (GPIO10,9).

Hi,
do you have a picture how your module is connected ?

I dont have a picture right now. I'll try to upload later.

But I've tried 2 setups:
1-) I soldered all the pins to headers then used 20cm(max.) wires for power
2-) Soldered on a PCB just for extending the pins to 1inch

All the grounds and 3.3V pins were wired/soldered including hardReset and TX pins. I dont think the distance from the source is a problem. which is on PCB less then 5cm. I've used LM117-SOT223 (http://www.ti.com/lit/ds/symlink/lm117.pdf) for 3.3V but no hope (with wifi). Still using DC source and reading 3.32V on carambola2 3.3V pins while module+wifi is up.

Thanks in advance.

Can you check voltage drops using oscilloscope when wifi turns on ?

Carambola2 works fine with any 3.3V fixed regulators such as LM1117, LD33 etc and a couple of capacitors. C2's power consumption that i've managed to measure is the same with this link: http://jeelabs.org/2013/05/07/carambola ... nsumption/
I didnot encounter any high peak current circumstance. There seems to be my electrical installation of the building was the problem. Additionally, it seems that C2 blows with 5V and if it derives more current then normal (3.3V / 400-500mA with only connected to a network) it also means blow up. Lastly, my tiny advice is to use solder as much as possible instead of wiring.

Thanks a lot @gedass