LM1085R 参数 Datasheet PDF下载

3A L.D.O. VOLTAGE REGULATOR (Adjustable & Fixed)

THERMAL CONSIDERATIONS

LM1085

The LM1085 series have internal power and thermal limiting circuitry designed to protect the device under

overload cinditions. However maximum junction temperature ratings should not be exceeded under continous

normal load conditions.

Careful consideration must be given to all sourses of thermal resistance from junction to ambient, including

junction-to- ase, case-to-heat sink interface and heat sink resistance itself. To ensure safe operating

temperatures and reflect more accurately the device temperature, new thermal resistance specifications have

been developed. Unlike order reguators with a single junction-to-case thermal resistance speccification, the

data section for these new regulators provides a separate thermal resistance and maximum juntion temperature

for both the Control Section and the Power Transistor. Calculations for both temperatures under certain

conditions of ambient temperature and heat sink resistance and to ensure that both thermal limits are met.

Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below

the die. This is the lowest resistance path for the heat flow. In order to ensure the best possible thermal flow

from this area of the package to the heat sink proper mounting is required. Thermal compound at the case-

to-heat sink interface is recommended. A thermarlly conductive spacer can be used, if the case of the device

must be electrically isolated, but its added contribution to thermal resistance has to be considered.

spacer can be used, if the case of the device must be electrically isolated, but its added contribution

to thermal resistance has to be considered.

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HTC