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internal switch of dc/dc converters

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nxavier

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top switch dc dc

hi.

what does the internal switch of dc dc converters do? is it different to the switch that a switching converter have?
i have seen some regulators that have this internal switch. i dont know if this is much better than simple switching regulators.

thanks.
 

tyassin

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power limited internal and external dc

The internal switch does the same as an external switch.
However because the switch is integrated in the IC, you will usually be limited to low power power operations, due to loses in the switch.
You will see that the internal switches usually have a Rds(on) at 100mΩ or more.

If you can live with the lower efficiency, then you can save a component which could make your application cheaper.
 

nxavier

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internal switch

tyassin said:
The internal switch does the same as an external switch.
However because the switch is integrated in the IC, you will usually be limited to low power power operations, due to loses in the switch.
You will see that the internal switches usually have a Rds(on) at 100mΩ or more.

If you can live with the lower efficiency, then you can save a component which could make your application cheaper.
so you mean this internal switch is the one that do the "switching" of a switching converter? (pardon the too many 'switch' word). this is the one that does not use external transistors, right?

im just confused if this internal switch is different from the one that do the switching on the converter.

thanks by the way for the immediate reply.
 

tyassin

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Hi

Just to clarify the switch is a FET, which is doing the switching.
Having an external FET means you can handle more power and also get more efficiency.

The IC containing internal FETs are generally more lossy.
 

nxavier

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thank you very much! that really helps!
 

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