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I am looking to replace a 4.3 inch TFT (480*270 px - 400-500 mA @ 5V) by a more energy efficient one (other sizes welcome) to go with my raspberry pi driven handheld emulation console.
What is the minimum intake that I have to take account, if I can find a screen that runs natively on the 5V or 3.3V that my battery or the Raspberry supplies?

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    \$\begingroup\$ Look for ones with led back lights. But most tfts will have the same energy consumption as that. That said, if the idle screen off consumption is too high, look at replacing the convertor or adding a relay to turn it off completely. \$\endgroup\$ – Passerby Nov 2 '15 at 16:33
  • \$\begingroup\$ Thanks for your input. I don't mind the idle consumption in general, but I have the feeling that it is an indicator that somewhere power could be saved in general. I will try to find one with an LED backlight. \$\endgroup\$ – kamuro Nov 3 '15 at 10:10
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Mobile phones give quite a good benchmark on display power consumption.

For example a Samsung Galaxy S5 has a 5", 1920x1080 pixels display. And it has a 2800 mAh battery and is able to do a benchmark at 200 nit for around 7.5 hours (based on phonearena).

So the phone needs an average of 375 mA during that time. I'd guess that most of it goes in the display, so there is not that much current to be saved, but they run on a lower voltage, so you can save some power. (If you calculate pixels per milliamp they are insanely more efficient)

It's quite easy to get your hands on those mobile phone displays, but it's a lot harder to get your hands on an efficient driver to use the displays outside of their normal environment (at least that's my experience).

I don't know which interface you want to use, but I think that's part of the problem, going from RPi -> HDMI -> Display is more power hungry than say a display which goes µP -> Display (embedded displayport).

The 3.3 V of the RPi is very weak, you won't be able to power a display directly from it. It's limited to 50 mA if I remember correctly.

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  • \$\begingroup\$ At the moment I am using a car monitor tft, which needs a DC DC converter (on-board) and produces a lot of heat. The connection is made via the component out of the RPi. I don't need more pixels since the original games were written for CRT TV's as display units. The low pixelcount should help to save energy compared to cellphones. The screen has an idle intake of 140 mA @ 5V (backlighting and TFT off), which I hope could almost completely saved by using a better energy conversion. Is that true? \$\endgroup\$ – kamuro Nov 2 '15 at 16:07
  • \$\begingroup\$ @kamuro 150 mA @ 5 V without anything going on sounds quite high yes. I don't know how that thing is built, so it's hard to guess why that is the case, maybe it's still converting the composite signal. You could use a relay or something similar to turn off the monitor completely. \$\endgroup\$ – Arsenal Nov 2 '15 at 20:47
  • \$\begingroup\$ As said just now in the comment above, I don't mind the idle consumption in general. I think the problem lies in a bad DC-DC conversion, but I don't know whether that is the trugh. I will try to find out by trial and error, the screen was quite cheap, so the learning effect is worth the loss if things go wrong. Thanks for your input, I learned from your answer and comment. \$\endgroup\$ – kamuro Nov 3 '15 at 10:13

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