Better driver for PWM

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varunme

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Is it better to use a transistor or a FET to drive a 3W LED using PWM, (considering cheaper transistor too)
what is the max current rating of BC549 and BC595 ?
 

BC549; BC550 NPN general purpose transistors
FEATURES
•Low current (max. 100 mA)
•Low voltage (max. 45 V).
APPLICATIONS
•Low noise stages in audio frequency equipment.
DESCRIPTION
NPN transistor in a TO-92; SOT54 plastic package. PNP complements: BC559 and BC560.
 

Most 3W LEDS draw high current, maybe up to 1 Amp so those transistors are far too small. A power FET will normally out-perform a bipolar transistor in low voltage high current PWM because they tend to have lower saturation voltages. This means lower heat dissipation and more current available to the LED.

Brian.
 

ok,
I have thousands of BC549 and BC595 available with me so, I asked about the BC549 and BC595
 
MSFET Would be better choice. If you want use available inventories of device with you may want to use few BJTs in parallel, but you need to make special arrangements for equal current sharing.
 

Dear varunme
Hi
why you , don't use a simple totem pole to drive your mosfet?
Best Wishes
Goldsmith
 

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