FS8860

Rev. 2.2

12/15

Thermal overload protection is designed to protect the FS8860 in the event of fault conditions. For continuous

Operating Region and Power Dissipation

Maximum power dissipation of the FS8860 depends on the thermal resistance of the case and circuit board, the

temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation

(

) (

)

JA

A

J

CA

JC

A

J

MAX

T

T

T

T

P

θ

θ

θ

−

=

+

−

=

board, copper traces and other materials to the surrounding air. For better heat-sinking, the copper area should

be equally shared between the IN, OUT, and GND pins.

If the FS8860 uses a SOT-223 package and this package is mounted on a double sided printed circuit board

Based on the maximum operating junction temperature 125 °C with an ambient of 25°C, the maximum power

dissipation will be:

() ()

W

T

T

P

CA

JC

A

J

MAX

25

.

1

80

25

125

=

−

=

+

−

=

θ

θ

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

A 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 FS8860 uses

a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-to-source on-resistance