Hi Stephan,

The spacing between Tip and Ring and between Tip and Ring and other circuitry is a geometric concern based on certain voltage requirements. When doing the layout be sure to consider the 3D effects of both creepage - the distance between two conductive circuits across the insulator and clearance - the distance between to conductive elements through the air (including metal enclosures, card guides and the like). For UL1950, the trace spacing requirements are .060" between Tip and Ring (T/T, T/R, R/R) for an 800V peak surge. And .100" (actual 2.5mm) between Tip and Ring and other circuitry @ 1000VAC RMS. 

Testing is sometimes performed in two manners - a voltage test and dimensional measurements so be sure to observe proper spacing rules for your application.

If possible it's best to remove any power and ground plane data from beneath the T/R circuits instead of trying to provide separate clearance for each pad or via. If T/R and other circuits are on adjacent layers it's beneficial to note on the PWB drawing that a minimum of 3 plies of pre-preg should be used between these layers. This potentially eliminates a test, I don't remember which one.

Keep in mind that creepage spacing is cumulative. By that I mean if the total distance between two pins of a multi-pin device meet the overall spacing requirement your golden. For example: A straight 3 pin connector has pins 1 & 3 connected to T/R, pin 2 is unconnected. The distance between pins 1 & 2 is .030" and the distance between pins 3 & 2 is .030". The combined distance is .060" which meets the requirement. Of course if pin 2 were connected you'd be porked.

Good Luck
Rick

Rick Smith
CAD Supervisor
ADC Broadband Infrastructure & Access
Wallingford, Ct. 06492
Ph 203 639 7670
FX 203 639 7601

Learn about ADC-The Broadband Company at www.adc.com





-----Original Message-----
From: Stéphan Renaud [mailto:[log in to unmask]]
Sent: Monday, April 23, 2001 1:52 PM
To: [log in to unmask]
Subject: [DC] UL-1950 certification


We need to get the UL-1950 spec. certification for one of our products.
We are in the process of purchassing the specs but it would be greatly
apreciated if meanwhile anyone of you could give us some information on what
design rules to follow on the pcb (spacing needed for ring voltage, ring
start, -48v, etc.).
Again, we appreciatte all the help. Thanks.

Stephan Renaud
Product Designer

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------