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So i want to make a rgb led strip setup with irfz44n mosfets. The datasheet says that once 4.5v is applied on the gate the mosfet will start to let through about 9 amps. My psu is only 5 amps. Does this mean i can't dim the colors when using the arduino's analog pins?

EDIT: Sorry for not being clear. I want to power my common anode led strip with a 12v 5a psu. Every color (red, green blue obviously) is connected to his own mosfet's drain, source pin going back to the psu's and arduino's ground. The gate i want to power with an arduinos analog pin. My question now is, will i be able to dim the leds since the gate-to-source picture on the datasheet says at 4.5 volts on the gate the mosfet will start to let 9 amps flowing from drain to source.

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  • \$\begingroup\$ It means you haven't enough power to light your LEDs. \$\endgroup\$ – Transistor Aug 5 '17 at 16:33
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    \$\begingroup\$ I don't see a link to your LEDs nor a schematic? \$\endgroup\$ – Andy aka Aug 5 '17 at 16:38
  • \$\begingroup\$ try phrasing as '... the mosfet will start to let through up to 9 amps'. \$\endgroup\$ – Neil_UK Aug 5 '17 at 16:43
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    \$\begingroup\$ voting to close as unclear, since without schematic, it's not clear what OP really tries to do. \$\endgroup\$ – Marcus Müller Aug 5 '17 at 16:45
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    \$\begingroup\$ You really don't want to analog dim the LEDs. Your MOSFETs will be dropping a lot of power and will get quite hot. You need to use PWM dimming. \$\endgroup\$ – DoxyLover Aug 5 '17 at 17:49
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IRFZ44N can't be driven from 5V (the datasheet specifies no RdsON for Vgs=5V).

See this answer, which is basically the same problem, and use the same FET.

https://electronics.stackexchange.com/a/322098/13616

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Regarding current.

let through about 9 amps

9 Amp is the maximum current the MOSFET can handle at that VGS without becoming to hot and break down and fail. If your LED consumes 5 Amp then you are below the maximum limit of 9 Amp = OK!

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  • \$\begingroup\$ So i will be able to dim the leds although the minimum volt stated on the gate in the datasheet is 4.5v? \$\endgroup\$ – Anonymus Aug 5 '17 at 18:09
  • \$\begingroup\$ I would use a additional transistor to increase the VGS on the MOSFET. arduinodiy.files.wordpress.com/2012/05/fet2_thumb.gif?w=535 \$\endgroup\$ – MatsK Aug 5 '17 at 18:18
  • \$\begingroup\$ Two bullets: 1. IRFZ44N isn't a suitable MOSFET, look for a MOSFET with TTL level. 2. If you have to use IRFZ44N Phillips datasheet shows it can be driven with VGS 6 Volt but poorly. \$\endgroup\$ – MatsK Aug 5 '17 at 18:28

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