Hello all. I have a power supply that I threw together using a linear replacement switching regulator made by CUI, part number is V7805-1000. I followed the reference circuit in the datasheet and added the caps that it recommends. I feed it 12VDC and I get a really nice and consistent 5VDC on the output. So, I would say the regulator works well.
My issue is when I attach my load to the power supply. My load is an intelligent LCD touch screen by 4D systems, part number uLCD-70. According to the data sheet, I supply 5VDC to it and they recommend a minimum of 500mA but preferred up to 1A for current. I am right within those specs and am even at the preferred max current of 1A. For the most part, everything works and the screen runs fine. I measured actual current draw of 610mA and it holds pretty stable at that.
The issue or question is, I happened to notice that I read a lower voltage of 4.3VDC when the screen is hooked up. As soon as I unplug the screen, it jumps right back to 5VDC and is pretty stable there. I am not driving any other loads with this supply/regulator, it is just for the screen. Is this normal to see this much of a voltage drop on my supply when my load is hooked up? Is there anything I can/should do to prevent this? Like I said, the screen still runs fine but I am .7VDC under their 5V requirement so I am concerned that the screen could act up.
I have attached datasheets for the regulator and the screen. Any ideas would be appreciated!
Thanks!
Mike
My issue is when I attach my load to the power supply. My load is an intelligent LCD touch screen by 4D systems, part number uLCD-70. According to the data sheet, I supply 5VDC to it and they recommend a minimum of 500mA but preferred up to 1A for current. I am right within those specs and am even at the preferred max current of 1A. For the most part, everything works and the screen runs fine. I measured actual current draw of 610mA and it holds pretty stable at that.
The issue or question is, I happened to notice that I read a lower voltage of 4.3VDC when the screen is hooked up. As soon as I unplug the screen, it jumps right back to 5VDC and is pretty stable there. I am not driving any other loads with this supply/regulator, it is just for the screen. Is this normal to see this much of a voltage drop on my supply when my load is hooked up? Is there anything I can/should do to prevent this? Like I said, the screen still runs fine but I am .7VDC under their 5V requirement so I am concerned that the screen could act up.
I have attached datasheets for the regulator and the screen. Any ideas would be appreciated!
Thanks!
Mike
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