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

[flote21]

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!

 

[FvM]

If your application doesn't need 5V, it would be more appropriate to convert to 3.3V in the first level, particularly if you plan to use linear regulators.

You should have a rough idea about the current consumption of each power net, e.g. by using the Altera power estimation tool, to decide if linear regulator are accpectable.

Starting from a 3.3V input, a LDO for 2.5V is mostly acceptable.

1.8V would be typically used for DDR2 RAM which might consume several amperes. Also the SSTL IO standard is rather power hungry.

1.2V can use a LDO for small, slow clocked designs. A high performance design might need 10 A and more core supply current, demanding for a 1.2V switching regulator.

 

[hobbyckts]

Are you going to use the part numbers which you have mentioned in the image?

Both the part numbers are suggesting that it is DC-DC converter and not the switching regulator.

 

[FvM]

Both the part numbers are suggesting that it is DC-DC converter and not the switching regulator.

Both are nonisolated DC/DC converter modules, respectively buck converters. I don't see what else should be a "switching regulator"?

Regarding the question in post #1, the main difference between both modules is the high input voltage range of ISL8216M, which most likele involves a higher pricce. Efficiency seems comparable at first sight. Both need to be supplemented with external input- and output capacitors.

 

[flote21]

Yes I already did the power estimator and I have the right LDO for supply the FPGA from the dc-dc converter.

On the other hand, respecting to the part numbers, both are dc-dc converters and I think that the main interesting difference between them is the low EMI performance of the LTM4606. However I don't know if this characteristic is so critical to make the decision. If you have another suggestion, i am very open minded.

Thanks

Both are nonisolated DC/DC converter modules, respectively buck converters. I don't see what else should be a "switching regulator"?