powering up a lilliput thru a regulator

**masch** · 01-24-2004, 10:24 AM

Hola

I read somewhere here that you need less than 1A to power a lilliput touchscreen.

I think the LM7812 should be able to power it up then no?

I'm sorry, I remember a year or so ago people are saying linear regulators are bad, but how come?

**R3l0ad** · 01-24-2004, 11:33 AM

I am running my Lilliput off of my PW-120 that has the ITPS connected as well.. Works great!!! Haven't had a problem as of yet!

**masch** · 01-24-2004, 11:56 PM

wha? hehe that wasnt the question.

but anyway, i got the molex DC2DC adapter.. its quite different than the PW120.. If you got your lilliput working on the PW120, I'm tempted to try on mine.. which is connected straight to the battery. Is this a bad idea?

I didnt know the PW120 regulated the 12V incomer

**Pudge** · 01-25-2004, 12:55 AM

Originally Posted by masch

I didnt know the PW120 regulated the 12V incomer

That's what the ITPS is for. So...

Battery-->ITPS-->PW120-->molex connector (molex is connector, morex is your PSU, just clarifying cuz you called your PSU a molex.) to the lilliput (12v is yellow, red is 5v)

**masch** · 01-25-2004, 01:58 AM

Doh, hehe. Thanks for the clarification.

So you run your lilliput of the ITPS eh? Doesnt that need something like 13V min to run? Can you run with the engine off and survive cranking? So I guess you arent running the lilliput off the 14.3V alternator while driving.. I wondered about that.

I just got my lilliput in the mail about an hour ago.. w00t. I guess most of my worries were unfounded. The lilliput came in with a cigarette lighter adapter.. meaning I dont have to build my own regulator for the power as I initially thought! (I guess I will have to build it anyway so that it will look better later)

I think I'll run a multimeter on my MOREX adapter to see if the 12V output is 14+V while running or if its safe enough to connect the lilliput directly to it.

**mportobello** · 01-25-2004, 02:05 AM

I saw somewhere the Lilliput uses about 500mA when up and running.

I asked a question about power supplies at avrfreaks and got some great answers:
http://www.avrfreaks.net/phorum/read...&t=59971#59971

7805 is simple, reliable, easy to use, but only 50% efficient and will probably require a significant heat sink

A switching regulator: 80% efficient, requires more external components, more expensive

Brian