A20-OLinuXino-MICRO available power

[ealex]

Hello

Are there any specification for the available power form the on-board power supplies ?
I'm having the following issue:

set-up:
- a20 micro board, no NAND
- 7'' LCD, back light set to 200 form script.bin
- SATA hard drive
- 6600mAh LiPo cell
- usb keyboard
- usb RTL2xxx SDR
- 9V, 2A switch mode power supply

With the power supply attached the board works perfect in that set-up, including battery charging with a peak current of ~ 1A.

When I remove the external power supply the 5V power rail starts glitching after ~ 5 minutes, and the hdd enters an infinite spin up / down loop - I've correlated this with the battery voltage falling below 4.15V. It seems that the 5V boost converter is not able to provide the requested power - U16 (SY7208) in the rev F1 schematic

I could not find in the available documentation some limits on how much power the user can pull out of the board.

Something like this will be useful:
- 3.3V rail max. current when running from external psu / battery ( ex: 800mA/500mA )
- 5V rail max. current when running from external psu / battery ( ex: 1A /800mA )
- total power available to the user when running from psu / battery - i don't know if the power controller will be able to supply max. values for 3.3 and 5v rails at the same time ( for example 0.5A on the 3.3V and 800mA on the 5V rails -> 1.65W + 4W -> 5.65W max available power )

[JohnS]

What does/do the datasheet(s) for the chips show?

(I doubt you can run a hard drive but if you can it won't be for long.)

John

[dave-at-axon]

I am finding that even with an LCD powered from the 3.3V rail, that the battery can't get as low as you would like simply because the 3.3V supply is not buck/boost but buck only so anything below around 3.4V spells disaster and I start to see flickering on the LCD.

I've setup the system to shutdown at around 3.7V which is not ideal and gives a lower operating life on battery but at least it works this way and the user does not see any flickering.

[jess]

... I've setup the system to shutdown at around 3.7V ....

Can you elaborate on how did you do it - in fex or some kind of hardware?

[dave-at-axon]

It's in the FEX file.

pmu_suspendpwroff_vol = 3700 (original was 3400)

I also changed this one as it was the same value.

pmu_pwroff_vol = 3700

[jess]

Thanks