EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: rexxar on February 14, 2014, 04:24:56 am
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I'm designing a circuit that will drive an RGBW LED from a single LiPo. I'm using MOSFETS to drive them with a PWM signal. The FET I chose from Mouser (I've not ordered them yet) is a PSMN022-30BL,118 (http://www.mouser.com/Search/ProductDetail.aspx?R=PSMN022-30BL,118virtualkey66800000virtualkey771-PSMN022-30BL,18), and it says it operates at logic level. If I'm reading fig. 6 on the datasheet correctly (p.6), it will pass ~7A at 3Vgs?
My question is, will this be suitable for driving about 500mA from a single LiPo cell? I've got about 2 sq in of PCB heatsinking for four FETs. I'm concerned that I won't be able to drive them into saturation and heat will be an issue. (That's all the space I could afford; it's a very small board)
I only understand the basics of how MOSFETs work, and I don't understand a lot of the values in the datasheet. Advice on this project and recommended reading for MOSFETs would be greatly appreciated.
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Checking the same datasheet (Fig 9) one can estimate the on-state resistance @3Vgs to be something around 100 mohm or so (the value is outside the chart making it a bit hard to estimate. The dissipation @500 mA would be just 25 mW so you should have no problems even though the switch is not properly in saturation.