Using Digital isolators instead of Opticouplers

TechGuy · 5th July 2008, 01:28 AM

Has anyone ever used Digital isolators in SMPS design? The big advantage I see is the much higher switching speed, but I am curious if any has run into issues using them.

Thanks

http://www.analog.com/en/interface/d...cts/index.html

jcx · 5th July 2008, 03:54 AM

I've used them for digital bus/control signal isoation in a strain gage amp, seem OK so far but I've not started testing EMI performance

read the app notes carefully, these do use magnetic coupling so it's possible putting them in a really bad spot could be problematic in a SMPS - know where your sw currents flow, and how far your magnetic component leakage fields reach

mflorin · 6th July 2008, 08:58 AM

Hi
I have used them to pass the PWM signal (PWM controller placed on secondary side) over the isolation barrier to driver circuit.
What I noticed is that at start-up when input side has an undefined supply voltage level (around 2 - 2.5V), the output generates some narrow pulses.
Those pulses can trigger your logics if, for example, such a digital isolator is used on a fault line.
It was the case of ADUM1100 but the manufacturer knows that behavior and I think they solved the problem by now (it happens about 2 years ago).

5th July 2008, 01:28 AM	#1
TechGuy diyAudio Member Join Date: Apr 2006 Location: Connecticut	Using Digital isolators instead of Opticouplers Has anyone ever used Digital isolators in SMPS design? The big advantage I see is the much higher switching speed, but I am curious if any has run into issues using them. Thanks http://www.analog.com/en/interface/d...cts/index.html

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
GB: Kerafol Keratherm Red Isolators (TO-220 / TO-247)	luvdunhill	Group Buys	139	11th March 2010 07:23 PM
audio isolators how to	mhtplsh	Solid State	0	24th May 2008 01:56 AM
High-Speed Digital Isolators?	Ryssen	Digital Source	2	20th December 2006 07:42 PM
Pneumatic isolators	Prune	Everything Else	2	18th February 2004 08:55 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

5th July 2008, 03:54 AM	#2
jcx diyAudio Member Join Date: Feb 2003 Location: ..	I've used them for digital bus/control signal isoation in a strain gage amp, seem OK so far but I've not started testing EMI performance read the app notes carefully, these do use magnetic coupling so it's possible putting them in a really bad spot could be problematic in a SMPS - know where your sw currents flow, and how far your magnetic component leakage fields reach

6th July 2008, 08:58 AM	#3
mflorin diyAudio Member Join Date: Jun 2005 Location: IASI	Hi I have used them to pass the PWM signal (PWM controller placed on secondary side) over the isolation barrier to driver circuit. What I noticed is that at start-up when input side has an undefined supply voltage level (around 2 - 2.5V), the output generates some narrow pulses. Those pulses can trigger your logics if, for example, such a digital isolator is used on a fault line. It was the case of ADUM1100 but the manufacturer knows that behavior and I think they solved the problem by now (it happens about 2 years ago).