Enable Start-up Time, (I

Enable Start-up Time, (I

20144146

20144147

Dropout Over Temperature (100mA)

20144105

Application Hints

POWER DISSIPATION AND DEVICE OPERATION

The permissible power dissipation for any package is a

measure of the capability of the device to pass heat from the

power source, the junctions of the IC, to the ultimate heat

sink, the ambient environment. Thus the power dissipation is

dependent on the ambient temperature and the thermal

resistance across the various interfaces between the die and

ambient air. As stated in (Note 5) of the electrical character-

istics, the allowable power dissipation for the device in a

given package can be calculated using the equation:

The actual power dissipation across the device can be rep-

resented by the following equation:

P

This establishes the relationship between the power dissipa-

tion allowed due to thermal consideration, the voltage drop

across the device, and the continuous current capability of

the device. These two equations should be used to deter-

mine the optimum operating conditions for the device in the

application.

EXTERNAL CAPACITORS

Like any low-dropout regulator, the LP5900 requires external

capacitors for regulator stability. The LP5900 is specifically

designed for portable applications requiring minimum board

space and smallest components. These capacitors must be

correctly selected for good performance.

INPUT CAPACITOR

An input capacitor is required for stability. The input capacitor

should be at least equal to or greater than the output capaci-

tor. It is recommended that a 0.47 µF capacitor be connected

between the LP5900 input pin and ground.

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