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18...36/24 Power Supply designing

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pzq

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sami conductor

Dear members,

I'd like to design professional type DC-DC power supply requirements as
follows:
Input: 18...36 Vdc
Output: 18....24 Vdc @ 170W
Design shall be realized without Boost partion i.e.
under 24 V input, the output follows the input (23in = 23out, 18in = 18out etc.)...and over the 24 V input ,the output will be reagulated to be 24 V.
This could be realized with e.g. Buck regulator with PMOS top-fet i.e. could get almost 100% duty cycle....or by Formard Converter topology.
Problem with PMOS top-fet is high losses i.e. difficult to find such kind PMOS with small thermal loss.
Please help me if somebody has some experience this sort of problem?! Thanks!
 

lll

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you can use N-mos instead of the P-mos.
But the gate driving circuits will be complex.
And you can use some special driving IC or drivng transformer to drive the high side N-mos in Buck regulator.
So the high efficiency can be obtained.
 

Noman Yousaf

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Re: 18...36/24 Power Supply

hello
i think this is not possible to get 18V in and exact 18V out through any sami conductor(tr IC etc)
you can use N type MOSFET for this purpose

Noman
 

Aoxomox

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Re: 18...36/24 Power Supply

Instead of an P-type mosfet in the high side you can use a N-type mosfet in the low side. Then high side goes straigth from input to output.
this type does not require a special gate supply voltage.

aOxOmOx
 

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