Pulster fixe(s) and rework

Helge Hafting helge.hafting at hist.no
Thu Mar 5 10:38:56 CET 2009

Andy Green wrote:
> Hash: SHA1
> Somebody in the thread at some point said:
> | On Thu, Mar 05, 2009 at 01:19:07AM +0100, Fox Mulder wrote:
> |> Andy Green wrote:
> |>> Johnny Tenfinger is right despite it sounds strange.  On some or all A5s
> |>> there is no base current limit resistor on the bipolar transistor used
> |>> to light the AUX LED.
> |>>
> |>> This "50mA" fault current then flows not through the LED (which has a
> |>> reasonable series current limit resistor), but through the GPIO IO cell
> |>> and the driver transistor base.
> |> If this is the problem than it really is a bad design flaw...
> |> Maybe i should test the AUX LED on my gta02v5 how much current it uses
> |> when it is on.
> |
> | Ouch. I just tested mine, and the AUX LED really uses that much (about
> | 50mA). Does a SOP exist to fix this?
> No there's no real hardware fix that's practical.
> We could have done something extreme like PWM the enable by software in
> FIQ ISR, but it would result in dim AUX LED even so, since the LED is
> not seeing the excess current but just normally lit.
> It was fixed on A6, I'm afraid we just have to let it lie and not use
> the AUX LED much as pointed out unless we're on external power.

Now that's an idea. How about using it as a battery charging indicator? 
the orange thing can be used for other purposes then.

Helge Hafting

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