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SS6341

even if the same device type is used for both. This is

because the gate drive applied to the upper MOSFET is

different than the lower MOSFET. Logic level MOSFETs

should

be

selected

based

on

on-resistance

and output voltage, allowable power dissipation and

maximum required output current. Power dissipation

should be calculated based primarily on required

efficiency or allowable thermal dissipation.

A Schottky diode is used as a clamp to prevent the

parasitic MOSFET body diode from conducting during

the dead time between the turn off of the lower MOSFET

and the turn on of the upper MOSFET. The diode’s rated

reverse breakdown voltage must be greater than twice

the maximum input voltage.

Linear Controller MOSFET Selection

The power dissipated in a linear regulator is :

)

V

(V

I

P

OUT

IN2

OUT

LINEAR

−

×

=

Select a package and heatsink that maintains junction

temperature below the maximum rating while operating at

the highest expected ambient temperature.

Linear Output Capacitor

The output capacitors for the linear controller provide

dynamic load current. The linear controller uses dominant

pole compensation integrated in the error amplifier and is

should be selected for transient load regulation.

Notes

FB2 and GATE2

FB3 and GATE3

These refer to the TYPICAL APPLICATION CIRCUITS

on pages 3 and 14.

Rev.2.01 6/26/2003