3v Or 3.3v Power Supply

[HenkZw]

I have seen several posts on the external power supply requirements.
But I'm not sure what voltage it should supply.

I read here and there that it should be 3V or 3.3V.
I'v tried a power supply at home which can generate 3V (at 1000 mA, 16VA).
The LCD flashes like mad, while the LCD is relatively peaceful when it is
battery operated. Or maybe my power supply is malfunctioning
(but looks in good condition).

Should the power supply be 3V or 3.3V ? :huh:

 

[Vimacs]

evrything vom 2.4 to 3.4 should be fine,
Sounds like your psu isnt working right, probably cheapass crap.
Make sure you get a regulated switching psu.

 

[Silberstein]

I have seen several posts on the external power supply requirements.
But I'm not sure what voltage it should supply.

I read here and there that it should be 3V or 3.3V.
I'v tried a power supply at home which can generate 3V (at 1000 mA, 16VA).
The LCD flashes like mad, while the LCD is relatively peaceful when it is
battery operated. Or maybe my power supply is malfunctioning
(but looks in good condition).

Should the power supply be 3V or 3.3V ? :huh:

​

Sounds like your psu isn't regulated, That is not good.

 

[HenkZw]

No, it wasn't cheap ! :unsure:
It could still be crap. I'll have to check.
How can you check the quality of the DC ripple of a power
supply (without a scope) ?

 

[luteijn]

No, it wasn't cheap ! :unsure:
It could still be crap. I'll have to check.
How can you check the quality of the DC ripple of a power
supply (without a scope) ?

​

if it's rel. low freq, you might be able to see on an _analogue_ volt meter, if it's +- 50 hz (likely), maybe with a crystal earpiece. I got a relatively cheap adapter from conrad, model sng12-24W-A, which works fine at 3v dc, upto 2A.

Pieter

 

[Squidge]

Not a 100% proof test, but...

Check the voltage without a load attached to the power supply, and then check the voltage again with a decent load (eg. 400 - 500ma or so) attached to the power supply.

If you find a massive difference, then you definitely need a new power supply, as the one you have doesn't regulate well enough. Some adaptors without regulation (or faulty) give out well over 4V when on the 3V setting and no load attached.

As a comparison, I can run my GP2X perfectly well enough to run things like power hungry emu's and movie playing at anything from 2V to 4V (I've not tried higher as I don't want to fry it). It'll boot up at 1.8V, but the power hungry stuff falls over. I never got a flashing LCD whilst doing the tests however.

 

[Dimacus]

Hello, this is my first post here, nice to meet you all.
Anyway, if you dont mind some soldering,
you can always build a regulated power converter that uses 5-20v to 3.3v
either using the LM2937IMP (3.3v regulator) alone
(depends on how mutch powe the GP2X needs, the LM2937IMP have a max rating of 600mA)

or you can use a LM317T along with a couple of other componets (since it's a varible voltage regulator) if the GP2X requires more power then 600mA.

I could make a small guide if there is any interesst.

 

[Vimacs]

if it's rel. low freq, you might be able to see on an _analogue_ volt meter, if it's +- 50 hz (likely), maybe with a crystal earpiece. I got a relatively cheap adapter from conrad, model sng12-24W-A, which works fine at 3v dc, upto 2A.

Pieter

​

hehe, i am useing the sng12-12w-a, works perfecktly and is cheaper

 

[HenkZw]

Thank you for your replies everyone.

I started this topic because I believed that I needed a
3.3 V power supply. Now that I know that the gp2x can
handle voltages from 2.4V to 3.4V without this having
an effect on the LCD, I'll look into checking my power supply.

This isn't my only power supply. I just picked this one because
it looked more robust (> 1000mA).

By the way, those screen images for music, games,
movies and other stuff. Can anyone read the small
print ? Why did they put it there ?
I tried using the 'loading.png' image in the update archive
(gp2xpatch-1.2.1.tar.gz). There seems to be something about
the US in there... :rolleyes:

 

[BradN]

Why doesn't someone find the voltage regulator part on the gp2x and look up the datasheet to find what its acceptable voltages are? I would but I don't have one...

 

[Silberstein]

Besides, doesn't the Gpx2 raise the voltage if to low, if there is enough current? Thought I read that somewhere here on this board.

 

[Dimacus]

Well im guessing that 2.4-3.0 is what it's "supposed" to get from the batteries (2x1.2v when on rechargeble, and 2x1.5v when on normal batteries).

But according to the specs on the GPX2 page it's 3.3v
so the range should be around 2.4-3.3v


Also, Silberstein:
Most electronic devices do have that effect , and generaly that's a bad thing.

Still, im more intressted in how mutch current it needs.
If we assume (I haven't seen any information about this) that it runs about 6h on 2850mAh batteries, that would give us about 475mA.

so a supply of 3.3v and 500mA should be enugh.

Ok, according to the Wikipage
"At 3.3V the unit draws ~380-480mA continuously (Firmware 1.0.1)"

 

[Squidge]

I posted a list somewhere of the current consumption at various voltage levels upto about 4V, a quick search will probably find it.

 

[furikuri]

I posted a list somewhere of the current consumption at various voltage levels upto about 4V, a quick search will probably find it.

​

Here is that topic: Latest Firmware Current Consumption

hmmm, lets do some idle tests in an attempt to find the optimal voltage

@ 2.5V = 410mA.
@ 2.9V = 340mA.
@ 3.3V = 300mA.
@ 3.4V = 290mA.
@ 3.6V = 280mA.
@ 3.7V = 270mA.
@ 3.8V = 260mA.
@ 4.0V = 260mA.

I think a battery capable of providing 3.7V is the winning one here. Who would have thought by just increasing the voltage by 1.3V, you would drop the consumption by 150mA ?

So, judging from these tests, for rechargable batteries, 3xAA (giving 3.6V) would give a LOT more playtime than 2xAA, simply due to the fact that the 2X doesn't have to waste as much energy to increase the voltage to it's preferred range.

Lets try this on mplayer:

2.5V - upto 850mA
2.9V - upto 690mA
3.1V - upto 650mA
3.3V - upto 590mA
3.7V - upto 530mA (270mA in stop mode)

Hmmm, a saving of over 300mA by just increasing the battery voltage. Nice

​

 

[donny662]

Well im guessing that 2.4-3.0 is what it's "supposed" to get from the batteries (2x1.2v when on rechargeble, and 2x1.5v when on normal batteries).

But according to the specs on the GPX2 page it's 3.3v
so the range should be around 2.4-3.3v


Also, Silberstein:
Most electronic devices do have that effect , and generaly that's a bad thing.

​

It's not a bad thing. It's essential to have a voltage regulator to supply the correct voltages neccessary to power sensitive devices like the processor without overheating it due to high voltage or underpowering it due to low voltage. Although, the built in voltage regulator won't be robust enough to handle too much variation.

Still, im more intressted in how mutch current it needs.
If we assume (I haven't seen any information about this) that it runs about 6h on 2850mAh batteries, that would give us about 475mA.

so a supply of 3.3v and 500mA should be enugh.

Ok, according to the Wikipage
"At 3.3V the unit draws ~380-480mA continuously (Firmware 1.0.1)"

​

It draws ~380-480mA continuously even when the unit is idle. When it is under load, watching a movie or playing a game, it will draw much more. I believe around 800mA is needed under load. GPH recommends a 1000mA (1A) power supply for a reason.

 

[Silberstein]

​

It draws ~380-480mA continuously even when the unit is idle. When it is under load, watching a movie or playing a game, it will draw much more. I believe around 800mA is needed under load. GPH recommends a 1000mA (1A) power supply for a reason.

​

But the official PSU is 2000mA right?

 

[donny662]

I don't know; I don't have one. I think I do remember reading that the official was 2A.

In the sparse user manual, it recommends 1A minimum.

 

[Dimacus]

Well im guessing that 2.4-3.0 is what it's "supposed" to get from the batteries (2x1.2v when on rechargeble, and 2x1.5v when on normal batteries).

But according to the specs on the GPX2 page it's 3.3v
so the range should be around 2.4-3.3v


Also, Silberstein:
Most electronic devices do have that effect , and generaly that's a bad thing.

​

It's not a bad thing. It's essential to have a voltage regulator to supply the correct voltages neccessary to power sensitive devices like the processor without overheating it due to high voltage or underpowering it due to low voltage. Although, the built in voltage regulator won't be robust enough to handle too much variation.

Yeah, but i was not reffering to the voltage regulator, but the side-effect (or what you should call it) that occurs when a battery is running low.

Still, im more intressted in how mutch current it needs.
If we assume (I haven't seen any information about this) that it runs about 6h on 2850mAh batteries, that would give us about 475mA.

so a supply of 3.3v and 500mA should be enugh.

Ok, according to the Wikipage
"At 3.3V the unit draws ~380-480mA continuously (Firmware 1.0.1)"

​

It draws ~380-480mA continuously even when the unit is idle. When it is under load, watching a movie or playing a game, it will draw much more. I believe around 800mA is needed under load. GPH recommends a 1000mA (1A) power supply for a reason.

​

ok, well i based my 500 on 2850mAh/6h
but that enormus current consumption could explain some of the firmware update problems we have today (just came of reading the firmware update/sd card problem thread).

Hmm, i just tought of this:
you take a standard computer psu Peripheral connector (standard power cable to harddrives and sutch)
take the +12 and gnd, connect it to a smal voltage regulation circuit (that gives 3.3v 1.5A max)

Well, not for portable use (for obvius reasons ), but when your updating firmware and sutch.

 

[Silberstein]

I don't know; I don't have one. I think I do remember reading that the official was 2A.

In the sparse user manual, it recommends 1A minimum.

​

Well, my thought was to bait someone explaining why it is so... I was really just a rethorical question . I mean, will the gpx2 be happier / just as happy with 2A? I have heard that tv-out requires a bit more juice, but 2A seems abit... overkill. And still, GP would be very stupid to supply a psu that could in some way hurt the unit.. :huh:

 

[reaper79]

I don't know; I don't have one.  I think I do remember reading that the official was 2A.

In the sparse user manual, it recommends 1A minimum.

​

Well, my thought was to bait someone explaining why it is so... I was really just a rethorical question . I mean, will the gpx2 be happier / just as happy with 2A? I have heard that tv-out requires a bit more juice, but 2A seems abit... overkill. And still, GP would be very stupid to supply a psu that could in some way hurt the unit.. :huh:

​

Just because a PS is rated at 2A(2000ma) doesn't mean that it will force 2 amps into the device. This is just the limit the PS can provide should the device want it. If the movie player is used, along with the TV-out, then I believe the drain is around 1100ma or 1.1 amps. Even a 1A PS wouldn't be happy at that range, and the power signal could become degraded/unregulated. This all depends on the quality of the PS of course, and whether it performs as rated. I've seen dinky little 1A power supplies that are good for 750ma, and I've seen 3 pound (weight not money) 1A power supplies that are happy @ 1.2 amps or more.