Powering FPGAs => DC-DC Power module Vs Switching Regulator.

[E.P (Gast)]

Hello people, I am designing the power supply chain of an ALTERA FPGA 
and I am wondering about which power converter is better to use. My plan 
is to create a power board to convert from 24v to 5v and from this power 
board drive 5v to the

FPGA board. Then I will use some LDO to generate from 5v the FPGA 
voltages (See picture attached). My big question is about which 
component is better to convert 24v => 5v. I was thinking to use a DC-DC 
power module (ISL8216M instead of a

switching regulator (LTM4606) because it is easier to implement (you 
only need a pair of coupling caps and go) you will have lower switching 
noise and lower heating dissipation. But I would like which are the 
drawbacks of using the DC-DC

power module and if some one has another good idea, please tell me.

Thanks a lot!

[uwe (Gast)]

ISL8216M is an switching regulator too!

[6a66 (Gast)]

E.P schrieb:
> Then I will use some LDO to generate from 5v the FPGA
> voltages (See picture attached).

Hi E.P.

depends heaviliy on the power requirement of the FPGA which you did not 
specify. In case the current you require is more than 1A you'l end up 
with a DC/DC vonverter there also.

E.P schrieb:
> My big question is about which
> component is better to convert 24v => 5v.

You will need a DC/DC switcher there anyway, you choose the one that you 
like best.

The ISL8216M is a complete module and is scheduled EOL at mouser, you 
might want to check whether that is available in the future. AND: it is 
quite expensive.

The LTM4606 is a chip for a regulator and you have to build everything 
yourself that is "contained" in the above module BUT it is cheaper.

You also might look into power supply solutions (Circuits) that supply 
all of the required voltages for the FPGA. Check the datasheet or the 
webpage of Altera.

rgds