EMRFD Message Archive 10073

Message Date From Subject
10073 2014-05-28 10:07:39 dl8ov Switched Mode Power Supplies
If any members of the group have experience in the design of switched mode power supplies please could they contact me at dl8ov(at)yahoo(dot)com

This matter is not urgent.

Thank you.

Peter DL8OV

10075 2014-05-29 10:30:15 Brooke Clarke Re: Switched Mode Power Supplies
Hi Peter:

I've done some using National Semi parts back when you could phone them and use their on line design tools.
One thing I discovered is that the efficiency depends on the quality ($) of the components you use with them.
Today rather than design a supply I look for one
10076 2014-05-30 09:21:05 m5evt Re: Switched Mode Power Supplies
I would agree with that statement about buying modules. Obviously it depends on the requirements of your system etc. but a small form factor, shielded SMPS will probably be better and cheap than something you design yourself.

Something I strongly recommend for SMPS, look for a fixed frequency of operation. Some change frequency depending on load demand. These varying harmonics can play havoc in RF systems.

Capacitor ESR and voltage rating require more attention that you would initially think with SMPS design.

Best regards,

Matt M5EVT.

10078 2014-05-30 09:42:45 Dave Miller Re: Switched Mode Power Supplies
I have been using the TI LMZ12001TZ-ADJ modules recently. They seem low noise and since everything but caps and a couple of resistors to set voltage are internal to the module they are very reproducible.
I was using the National switcher modules from Fleabay but they are hit and miss and very noisy.
I look at it as its a tradeoff of price versus performance. The module are in the $13.00 single piece from Digikey but they also complies with EN55022 Class B.

I have found them to be very suitable in my SDR project and have replaced the Ebay specials.