Current requirements for 20x4 VFDs

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paramotor
LCD?
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Joined: Wed Apr 18, 2007 2:57 am

Current requirements for 20x4 VFDs

Post by paramotor » Wed Apr 18, 2007 3:02 am

I had 16x2 VFD display for my project that worked fine. I needed more space to display stuff so I replaced it with 20x4 VFD display. The way this new display behaves is it comes on displaying my info for about a second, then comes off. It is connected to MCU. MCU continues to work, but VFD doesnt come on anymore. If I reset the power, it does come on for a second, then immediately off. I suspect it draws more current. Does it sound like it is an issue of insufficient current for VFD? How much current does 20x4 actually draw? I have 1A 5V regulator.

Henry
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Post by Henry » Fri Apr 20, 2007 7:06 am

Hello,

The 4x20 VFD can have a 550mA in rush power requirement. The current draw after is dependent on how many pixels are ON, so I would recommend a 350mA power supply or so... But Raquel will double check on that for you.
Henry J.
President
Matrix Orbital

Raquel
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Post by Raquel » Fri Apr 20, 2007 2:13 pm

Hello paramotor,

The power supply current for when all of the dots in the screen is lit is 350mA max (275mA typical). The in-rush current is anticipated to be twice as the normal current. So a power supply that can handle 700mA should be sufficient.
Raquel Malinis
Design and Development
Matrix Orbital

paramotor
LCD?
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Joined: Wed Apr 18, 2007 2:57 am

Post by paramotor » Fri Apr 20, 2007 4:35 pm

thanks guys. i found out what the problem was. it was NOT a power supply. 20x4 parallel VFD (from M-O) is not exactly Toshiba compatible and would malfunction on some commands that 16x2 VFD (or any truly compatible LCD) would support fine.

Raquel
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Post by Raquel » Fri Apr 20, 2007 4:46 pm

Glad to hear that you've figured it out.

Best Regards,
Raquel Malinis
Design and Development
Matrix Orbital

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