Selecting right P Mosfet

Is anyone aware of P Mosfet (SMD), that can handle 6Watts of power.

The heat sink area can max be 2x2 Cm x 4 layers

6 Watts - Steady State

Hi,

I´d go to a MOSFET manufacturer internet site and use their selection guide.

***
BTW: 6W is 6W, independent of P-Mosfet, N-Mosfet, LED, resistor...
Therefore I assume 2x2cm will be problematic in either case.

Klaus

I did search but the max on SMD I could find was 2 or 2.5 Watt and that again not on Ta of 25deg celcius

Hi,

this is nonsense.

I used farnell, selected
* P-ch
* P_tot>6W
* SMD (mostely)

--> 462 hits.

https://de.farnell.com/webapp/wcs/s...26970,310189078,311896305,311858611,310198698


Klaus

The question is ambiguous. Does "handle 6W" mean MOSFET power dissipation or switched power? If it's meant as power dissipation, I agree with post #2. It won't work on 2x2 cm without an additional heat sink.

I am designing a battery charger (li Ion, series dual) using MCP73842

Max input voltage is 10.5V (Vdd)

Battery Specs

Minimum cutoff voltage is at 5.2V
Max cutoff voltage at 8.4V

Charge Current I am using is 1A (Minimum)

Worst Case Pd is when the changing shifts from Preconditioning to Constant Current

which is (10.5V - 5.2V) / 1A = 5.3Watts

The area that I max have for Mosfet is 1.5 or 2 x 1 Cms each layer (Its a 6 layer board)

Schematic I am using is

**broken link removed**

The Board File is



As you can see there hardly is any space.

The Max height I can have is 3mm. This area is below the PCB and will finally sit very close to ABS

More heat can melt that plastic.

Considering worst case wattage (5.3 to 5.5Watt) has to be handled by the MOSFET and I am not sure how to choose appropriate part or go ahead from here.

Maximum power dissipation is limited by the enclosure and PCB size rather than transistor.

If you can't handle 5.3 W inside the enclosure and don't want to reduce the charging current, go for a switch mode charge controller.