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I'm interfacing a TFT display with MCU which requires 450mA current & 3.3V.

In power supply section I have used regulator ICs to get 5V & by using two diodes I'm getting 3.3V. For filtering in power supply I have used inductor.

but the display requires a 450 mA current which is not provided. & my display was getting reset because of not enough supply current. It led me to remove inductor & shorting it. now section is working & display is stable. But it will led to noise in power.

One remedy to this scenario I heard ( NOTE - I don't know exactly about it & I'm not sure Whether i'm saying it right. If it's wrong then please correct it) - we can use winding around an Inductor & then we can use it to provide enough current supply to display.

If any alternate solution is available with this please let me know.

NOTE - I'm not asking about how to regulate supply to 5V or 3.3V. I'm talking about the inductor which is used in filtering of power supply. How it is related to current if it is. power supply section schematic

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  • \$\begingroup\$ Link to the inductor's datasheet would be helpful, the information you need is probably in there. \$\endgroup\$
    – user16324
    Commented Dec 17, 2014 at 11:48
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    \$\begingroup\$ Also, 1N4148 is not a power diode. It's only supposed to handle about 75 mA of average forward current. At 450 mA, the voltage drop will be about 1.2V per diode. \$\endgroup\$
    – Dave Tweed
    Commented Dec 17, 2014 at 12:21

2 Answers 2

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First of all the 2 diodes will not reduce the voltage from 5 to 3.3. Additionally you make the output voltage more noisy as the amount of voltage dropped depends on the current drawn. Use LM1117-3.3 regulator instead.

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Inductors are far from being ideal components.
Yours could have a significant resistance component to it which will cause a voltage drop when you try to draw any current through it.
Have a look at its datasheet (or measure it with a reasonable accurate meter) to see if this is causing your trouble.
And as others have already mentioned, the 1N4148 is not at all suitable for anything close to 450mA, nor is that a good way to regulate from 5V to 3.3V if you need any degree of reliability.

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