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Heat Disspiation from Voltage Regulator

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ricky_wcy

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Dear All,

I got a problem by using voltage regulator

Condition (No load):

Adaptor (9V) -> Schottky diode (0.4V) -> Voltage regulator (3.6V)
Heat dissipation = 9 - 0.4 - 3.6 = 5V

Solutions requirement:

As less as component used as possible

Thanks,
Ricky
 

Method1:Use a lower Vss
Method2: Use a DC-to-DC convertor.
Method3: Mount the regulator onto a heatsink.
 

Add another 6V voltage regulator and spread heat between these two.
DrWhoF
 

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Dear All,

Thanks for your suggestion.
We meet the problem is:
1> Not enough space for PCB layout

so, I am looking for a stepdown DCDC
(Built in MOSFET and schottky diode, use Ceramic cap outside)
with little components. Do you know which one?

Thanks,
Ricky
 

To avoid this problem sometime I use one or 2 diodes(1N4007) in series with input of regulator to drop 1 volt having less Vss. These diodes will dissipate some power.
 

You didn't state the full load current requirement. However, there are several buck regulator ICs available (NSC, Maxim, Linear) that provide output current on the order of 1A, with few (or no) external components. These switchers typically provide 80% or better efficiency, alleviating the heat sink problems. An example is the National LM2825. It provides 1 Amp with no external components. It has a 24 pin dip package. There are many others available in surface mount packages. Most of these require an external inductor and an external capacitor. Visit the Maxim, National, Linear websites.
Regards,
Jon
 

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