Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Circuit input for EMC two capacitores 90 degree

Status
Not open for further replies.

leomecma

Full Member level 5
Joined
Jun 17, 2005
Messages
244
Helped
14
Reputation
28
Reaction score
1
Trophy points
1,298
Location
Brasil
Activity points
3,933
Anyone knows why some input circuit use two series capacitors in 90 degrees between input and GND?
 

Hi,

I assume you mean 90° mechanical orientation. This has nothing to do with electrical function.

--> show us the schematic. This tells the electrical function.

Klaus
 

Hi,

I assume you mean 90° mechanical orientation. This has nothing to do with electrical function.

--> show us the schematic. This tells the electrical function.

Klaus

Hi Klaus, yes 90 degrees mechanical. I have found two circuits in last week that use this arrangement, in one the person said that it was necessary to EMC tests pass. The second is a Texas Instruments application note without details about this configuration.

TI application: https://www.ti.com/lit/ug/tiduc41/tiduc41.pdf look schematic at page 16 and PCB at pag 1.

The second circuit is:

image003.jpg
 

An FAE told me that the redundant capacitor series circuit is required by automotive standards to reduce the risk of supply shorts. The 90° placement might be chosen to avoid simultaneous damage of both capacitors by board flexure.
 
An FAE told me that the redundant capacitor series circuit is required by automotive standards to reduce the risk of supply shorts. The 90° placement might be chosen to avoid simultaneous damage of both capacitors by board flexure.

That is the correct explanation for ceramic surface-mount capacitors. It is common for them to fail to short when they ***** because of mechanical stress.
It is even safer to remove the capacitor(s), but then expect the design to fail in EMC testing.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top