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Based on a maximum operating junction temperature 125°C with an ambient of 25°C, the maximum power dissipation will be:
(TJ −TA) (125−25)
PMAX =
=
= 0.555W
θJC +θCA
180
Thermal characteristics were measured using a double‐side board with 1”x 2” square inches of copper area connected to the
GND pin for “heat spreading”.
Dropout 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 RS7100 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)×IOUT
DS‐RS7100‐14 April, 2010
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