[RFI] "Efficient" replacements for linear voltage regulators

[Dale]

All,

I thought that the technically inclined on this list might want to be aware that at least one switching power supply manufacturer has now come out with "equivalent" replacements for the ubiquitous LM78-- and LM79-- series of IC voltage regulators that have been around for decades.  Touting efficiencies in the 90% range and that no heat sink is required (in some applications), few external parts are needed.  

So they say ... well, the new devices do required the input and output side by-pass caps as per the linear originals.  The switching frequency is not consistent, either, but seems to be around 300 kHz.  Here is the link:

http://www.cui.com/dc-switching-regulators

To be fair, if a manufacturer (or serious hobbyist) does proper pc board layout and follows good EMC design practices, an end-user device that incorporates one or more of these new chips can be just as RF "clean" as the linear versions (when checked externally).  However, design and manufacturing shortcuts to save a few pennies can easily result in more RFI screamers being foisted upon the market place. 

Please note that if a hobbyist ("ham") buys one of these and does a drop-in on a circuit board that had an LM78-- series device on it, the net result is not likely to be very RF clean.  The good news will be less heat, but you had better like more hash with your lower temperature.  Note that these devices are offered in pin-compatible (for TO-220) plastic packages.  My scary thought offering for Halloween.

73, Dale
WA9ENA