On Sat, 18 Jul 2009 19:18:10 +0100, you wrote:

>>I do it with an external mosfet for 3A and work very well,
>>but I don=B4t be sure if this IC can work with an external
>>P MOSFET for 20A.
>
>This would probably require some serious analysis of the output current =

>capability of the chip to see if it can drive the gate capacitance of the =

>FET. A 20A FET will have significantly higher gate capacitance than a 3A =

>FET, so your switching currents will be much greater. =


At that current you'll be paying enough for magnetics and FETs that you rea=
lly should look at paying
a little more for a controller designed for this power level instead of try=
ing to bodge a cheaper
part into doing something it isn't really designed for. If nothing else the=
 saving in heatsinking
will probably pay for the cost of a more efficient controller. =


There are approximately one gazillion DC-DC chips out there so I'm sure you=
'll find something more
suitable.

-- =

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