DC TO DC Converter switching frequency

[ballimo]

Hello All,

I want to use a DC TO DC converter to supply 3.3V for a high speed design, usually I put a linear regulator (LDO) after the DC to DC converter, but in this case this is not possible because I will exceed the power budget.

I find two DC to DC converter with an output voltage of 3.3V and the required current rating ...., but one has a switching frequency of 0.5 MHz the other 2 MHz.
My question: is it better to use 0.5 MHz or 2 MHz as switching frequency for this high speed design? I know that with a proper filtering I we can reduce the output AC ripple, but does this mean that the filtering is the most important not the switching frequency?

Thanks,

Ballimo

 

[hearter]

why you want to pick 2MHz instead of 0.5M? explain to me, both are very high to me.

 

[barath_87]

If proper layout constraints are taken care switching frequency is not a problem. As you might know this is the frequency at which the PWM inside the regulator will operate. There is a trade off between switching freq. and component footprint. If you are still to worried about it then you can go for POLA(PTH series) modules available from TI where you need not take extensive layout considerations while designing an SMPS circuit.
**broken link removed**

 

[ballimo]

I was searching 5V to 3.3V DC to DC converter with an output current of 2A and a small package, you will not find one with a switching frequency lower that 0.5 MHz (or maybe 250 KHz).

PTH series has a huge footprints, I want a very small one( the PCB dimension is small), My question is : is 0.5 MHz or 2 MHz switching frequency better for a high speed design? as you said the important is filtering and layout it doesn't matter what is the switching frequency. right?

Thanks,

Ballimo

 

[barath_87]

I was searching 5V to 3.3V DC to DC converter with an output current of 2A and a small package, you will not find one with a switching frequency lower that 0.5 MHz (or maybe 250 KHz).

PTH series has a huge footprints, I want a very small one( the PCB dimension is small), My question is : is 0.5 MHz or 2 MHz switching frequency better for a high speed design? as you said the important is filtering and layout it doesn't matter what is the switching frequency. right?

Thanks,

Ballimo

higher the the switching frequency lower will be the component footprint of your switching circuit.But your efficiency will also come down as switching frequency increases. I don't think it will have its affect on high speed design as long as proper layout guidelines are taken care(as stated by you).

Please correct me if I am wrong.

Barath Ramesh

 

[ballimo]

I think you're right.

what I know is that the switching frequency will affect the high speed signal, it will add some harmonics.... usually using the layout recommendation in a data sheet will minimize these effects.
what I know is that the AC ripple amplitude (at the converter output) and the ripple frequency (= switching frequency) will affect the high speed signal; for sure minimizing the AC ripple amplitude is good, but I am not sure if it is good to use low (0.5 MHz per example) or high switching frequency (2 MHz) ? maybe lower frequency is better...