Dear Dennis... analogZONE's Dennis Feucht answers your design queries in his new Circuit Design Clinic! March 2006

analogZONE presents a new, interactive analog design service to readers! Send us your design questions (with relevant data; schematics in JPEG or GIF, please) for some free engineering advice from analogZONE's circuit consultant, Dennis Feucht, on how you might solve a design problem or improve circuit performance. Submissions may be edited for clarity or brevity, and submitters and their email addresses will remain anonymous (unless otherwise indicated). Please send your questions to Dennis here.

Low Output-Voltage CATV Flyback Converter (Continued)

We continue the questions from a 5 W flyback converter designer working on a CATV application.

Converter Input/Output Isolation

Dear Dennis:

The converter input is CATV, for which one side is hard ground, so an isolated supply is needed. The voltage-sense input using a half-wave rectifier is tickling off such a light current that I am "cheating" that directly from the input.

 

For Dennis' response and more of this month's circuit design queries, download the current PDF file here.