Author Topic: question about step down buck converters  (Read 855 times)

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Offline little_carlos

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question about step down buck converters
« on: March 20, 2016, 02:07:17 pm »
Ive seen that from older to newer, they work with higher frecuencies, whats the main reason to do that? the only thing i know is that, the size of the low pass filter gets reduced, but, is that the only reason? does it makes them more efficient? could that cause bigger interferienece?
Thanks for your time

Offline SeanB

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Re: question about step down buck converters
« Reply #1 on: March 20, 2016, 02:12:40 pm »
Smaller size of the magnetic components, smaller value capacitors needed on input and output, smaller switching transistors and most importantly the loop response is so much faster leading to better regulation on step changes. The higher frequency also means less copper needed in inductors making them cheaper to wind for the same output power, and you can use cheap ceramic SMD capacitors instead of large electrolytics in many cases.

Higher frequency also means that if you want a smooth DC output with reduced ripple you need a smaller post switcher LC filter yes, but the inductor in the converter is doing much more than low pass filtering.

Offline danadak

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Re: question about step down buck converters
« Reply #2 on: March 20, 2016, 02:49:03 pm »
The downsides are the generation of noise into the RF area, the
need for Cs that act like a C at high frequency, eg. esr curves
still predominantly capacitive at the higher frequencies. Need for
better bypassing. Switches that incur higher Pdiss because of
switch drive dissipation. Increased coupling on PCB trace to trace
in sensitive signal paths......

To name a few.

Regards, Dana.
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer

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