FS8853 datasheet(12/15 Pages) FORTUNE

12 / 15 page

FS8853

Rev. 2.7

12/15

If the FS8853 uses a SOT-89 package and

this package is mounted on a double sided

printed circuit board with two square inches

of copper allocated for “heat spreading”, the

resulting θJA is 180 °C/W.

Based

maximum

operating

junction

temperature 125 °C with an ambient of 25°C, the

maximum power dissipation will be:

() (

)

MAX

555

180

125

−

Thermal characteristics were measured using a

double sided board with 1” x 2” square inches of

copper area connected to the GND pin for “heat

spreading”.

Input-Output Voltage

regulator’s

minimum

input-output

voltage

differential, or dropout voltage, determines the

lowest usable supply voltage. In battery-powered

systems, this will determine the useful end-of-life

battery voltage. The FS8853 uses a P-channel

MOSFET pass transistor, its dropout voltage is a

function of drain-to-source on-resistance (RDS(ON))

multiplied by the load current.

VDROPOUT = VIN-VOUT = RDS(ON) x IOUT

FS8853 Datasheet(PDF) 12 Page - Fortune Semiconductor Corp.