Question Power suggestion for the 5” ZJ050NA-08C?

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I’m building an N64 portable and have been researching/collecting parts for the build based on the BOM and various threads posted here. For video, I’ve settled on the 5” ZJ050NA-08C using the KYV-N2 V6 driver board. Before I order the display I wanted to confirm it will work with my power plan.

I am planning to use a 7.4V battery system and have a converter regulating the voltage down to 3.3V for the N64 and audio amplifier. I see the display can run on anything from 6.5-13.5V so I should be able to run it directly from the 7.4V. However, the driver board says it wants 12V. I cannot seem to find a voltage range spec on the driver board. Does anyone know if I can run it on the 7.4V? If not, how do you work around the supply issue? Another power converter?

Thank you for your time and help.
 

jefflongo

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Most displays just step the voltage down from 12v to 5v so it will probably just work on 7.4v. If it doesn't, depending on the drive board, it might be possible to run on 3.3v with some modifications.
 
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I think you are looking at the wrong section of the datasheet - that power range you mentioned is listed in the "absolute maximum ratings" section - these are stress ratings, and are just the range that if you go outside you might damage the part, not values that the part can be expected to correctly operate at.

The numbers you should be looking at are the ones in the "typical operation conditions' table (3.2 in my datasheet) - and that specifies a range for AVdd of 10.2-10.6V with a typical value of 10.4V - this is what you want to aim for to make the panel actually work.

You also have the two LCD drive voltages - Vgh (17V) and Vgl (-7V) - both of these can be easily generated using simple regulator typologies from stated 9-16V input range of the driver board - but it might be a problem getting them from a depleted 2S Li+ battery pack, even using a conservative 6.8V cutoff (I.E. 3.4V/cell).

I would recommend testing the driver board on a bench PSU @9V and then slowly reducing the supply while monitoring the LCM drive voltages and see when they start to go out of spec.
 

Aurelio

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I think you are looking at the wrong section of the datasheet - that power range you mentioned is listed in the "absolute maximum ratings" section - these are stress ratings, and are just the range that if you go outside you might damage the part, not values that the part can be expected to correctly operate at.

The numbers you should be looking at are the ones in the "typical operation conditions' table (3.2 in my datasheet) - and that specifies a range for AVdd of 10.2-10.6V with a typical value of 10.4V - this is what you want to aim for to make the panel actually work.

You also have the two LCD drive voltages - Vgh (17V) and Vgl (-7V) - both of these can be easily generated using simple regulator typologies from stated 9-16V input range of the driver board - but it might be a problem getting them from a depleted 2S Li+ battery pack, even using a conservative 6.8V cutoff (I.E. 3.4V/cell).

I would recommend testing the driver board on a bench PSU @9V and then slowly reducing the supply while monitoring the LCM drive voltages and see when they start to go out of spec.
All the LCD driving voltages you have mentioned are handled by regulators on the driver board. On there, all of them are obtained from a 3.3V input (got by previous regulating stages). VGH and VGL are usually driven by charge pumps, since they need very low current. AVDD is obtained with a switching step-up.
As Jeff said, these boards can all run easily with 5V or less. The bottleneck is given by the backlight driver, which sometimes requires 5V, some other times it's fine with 3.3V (it depends on the specific regulator and the load)
 
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All the LCD driving voltages you have mentioned are handled by regulators on the driver board. On there, all of them are obtained from a 3.3V input (got by previous regulating stages). VGH and VGL are usually driven by charge pumps, since they need very low current. AVDD is obtained with a switching step-up.
As Jeff said, these boards can all run easily with 5V or less. The bottleneck is given by the backlight driver, which sometimes requires 5V, some other times it's fine with 3.3V (it depends on the specific regulator and the load)
OK, it sounds like that specific board has already been tested - but the general advice of putting in on a bench PSU and testing it still holds since it's being used outside of the stated spec.

My personal bias would be to run the step-up regs from Vbatt (or Vsys if you're using a BMS chip) simply for efficiency reasons, since running them from 3.3V means you have two sets of losses (in the initial buck converter and then the boost converter) and would also result in the boost converter having to run at a higher peak inductor current, which typically doesn't help efficiency either.
 

Noah

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I think you are looking at the wrong section of the datasheet - that power range you mentioned is listed in the "absolute maximum ratings" section - these are stress ratings, and are just the range that if you go outside you might damage the part, not values that the part can be expected to correctly operate at.

The numbers you should be looking at are the ones in the "typical operation conditions' table (3.2 in my datasheet) - and that specifies a range for AVdd of 10.2-10.6V with a typical value of 10.4V - this is what you want to aim for to make the panel actually work.

You also have the two LCD drive voltages - Vgh (17V) and Vgl (-7V) - both of these can be easily generated using simple regulator typologies from stated 9-16V input range of the driver board - but it might be a problem getting them from a depleted 2S Li+ battery pack, even using a conservative 6.8V cutoff (I.E. 3.4V/cell).

I would recommend testing the driver board on a bench PSU @9V and then slowly reducing the supply while monitoring the LCM drive voltages and see when they start to go out of spec.
Honestly as good as this explanation is I think it would go over many of our member's heads (mine included!) and cause more confusion than anything. :P

As Aurelio said we've tested these boards as well as various others to work with lower voltages.

@Lab Minion I'm pretty sure I've used the exact panel you're talking about. If you post a picture here I can tell you which components to remove from the driver board and where to put 5V.
 
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Thank you for all the advice! The display+control board is on order so I can't provide a closeup at the moment. I attached the largest pic I could find of the board for now. I certainly will try the bench test to see how low it will go when it comes in. Here's my power and video parts I'm sourcing so far:
Trying to go by the book as much as possible based on the expertise here. Ideally, I'd like a display/board that I don't have to modify since I have to build a few of these. Does anyone know of a new, available display that can run reliably with a 7.4V input?

Edit: Just found this one being used in a modification for N64 with input voltages of Vcc = 3.3, Vled = 5.0: https://www.ebay.com/itm/AT056TN53-...704347?hash=item443a4a001b:g:58wAAOSwft9cpmoT
Perhaps a better option?

Edit 2: Well that was only the screen. The control board imposes the same issues it appears: https://www.ebay.com/itm/VGA-AV-LCD...477053?hash=item56c502b77d:g:pQwAAOSwyzxc38WS
 

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@Noah were you ever able to deliver an answer to Lab Minion on which componet to remove and where to apply 5v for this board? I am running this exact board for a portable I am working on and this information would be very helpful to use and reference in the future.
 

tzmwx

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3D0BA401-7C0B-4185-9413-B4701F121E1C.jpeg
@Noah were you ever able to deliver an answer to Lab Minion on which componet to remove and where to apply 5v for this board? I am running this exact board for a portable I am working on and this information would be very helpful to use and reference in the future.
 
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