Author Topic: Trace Width along the path to next component  (Read 3028 times)

0 Members and 1 Guest are viewing this topic.

Offline Falcon69

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
Trace Width along the path to next component
« on: September 04, 2014, 12:04:20 am »
Can the trace on a pcb be lessened in width as it goes down it's path to the next component? 

Or does it need to stay the same? I wouldn't think it would have the same current going through it from one component to the next.

Something like, the first trace between ground (or power) and component one (for example) would be 1.3mm, then between one and two would be 1mm, then between two and three would be 0.7mm, then between three and four would be 0.4mm, etc.  This of course would be if each component, like a resistor, was the same value and had the same voltage/current draw.
 

Offline kizzap

  • Supporter
  • ****
  • Posts: 477
  • Country: au
Re: Trace Width along the path to next component
« Reply #1 on: September 04, 2014, 12:20:47 am »
the resistance of the trace is going to increase as you decrease the width. That will mean that you might increase heat at a certain point, and all that nasty stuff.

If you have any significant current flowing, I would suggest not thinning down the trace, but giving as much allowance as possible/reasonable as you can.
<MatCat> The thing with aircraft is murphy loves to hang out with them
<Baljem> hey, you're the one who apparently pronounces FPGA 'fuhpugger'
 

Offline Falcon69

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
Re: Trace Width along the path to next component
« Reply #2 on: September 04, 2014, 12:26:46 am »
The trace carries a max of 2.06A when all 8 components are on.  thus, each branch will carry roughly 258mA of power. 

I asked this, because I was trying to save circuit board space.
 

Online tautech

  • Super Contributor
  • ***
  • Posts: 16324
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
Re: Trace Width along the path to next component
« Reply #3 on: September 04, 2014, 12:34:17 am »
By all means if as you say the current diminishes ~250 mA per device, step trace width down accordingly as you supply each device.
I have often seen this done on PCB's.
Avid Rabid Hobbyist
 

Offline Falcon69

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
Re: Trace Width along the path to next component
« Reply #4 on: September 04, 2014, 12:41:06 am »
Ya, that is what I was asking tautech

Something like this.

The bottom trace is power, the top is ground.

According to the trace width calculator, 0.81mm width at 1oz. copper is suffice for 2.06A.  I have the trace at the start drawn at 0.95mm and reduces as it goes down it's path.
 

Offline Rudane

  • Regular Contributor
  • *
  • Posts: 80
  • Country: us
    • Electrical Engineering 101
Re: Trace Width along the path to next component
« Reply #5 on: September 04, 2014, 12:45:40 am »
There is nothing wrong with this. Each trace should be as large as possible within reason. I always look at the current expected on the trace to determine if my width is adequate. I start with big traces in my power supply and decrease them appropriately.

Edit: From looking at your design, are you really saving board space?
« Last Edit: September 04, 2014, 12:47:20 am by Rudane »
Voltage appears across and current flows through.
 

Offline andtfoot

  • Supporter
  • ****
  • Posts: 352
  • Country: au
Re: Trace Width along the path to next component
« Reply #6 on: September 04, 2014, 12:48:47 am »
Just an example of how I read it for clarification


edit: bugger... didn't see the picture in the reply above... Redundant post now.
« Last Edit: September 04, 2014, 12:50:34 am by andtfoot »
 

Offline Falcon69

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
Re: Trace Width along the path to next component
« Reply #7 on: September 04, 2014, 12:48:56 am »
awesome, thank you guys. I will design accordingly.

I understand about the heat thing, but these traces won't see a continuous current go through them, except for may just a few seconds.  Plus, I have made them larger then they need to be.  I may even opt for 2oz. copper boards, just to reduce the voltage drop that may happen.
 

Offline Falcon69

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
Re: Trace Width along the path to next component
« Reply #8 on: September 04, 2014, 12:49:44 am »
more or less andtfoot.  Just like that.
 

Offline Mechatrommer

  • Super Contributor
  • ***
  • Posts: 9204
  • Country: my
  • reassessing directives...
Re: Trace Width along the path to next component
« Reply #9 on: September 04, 2014, 11:14:29 pm »
I asked this, because I was trying to save circuit board space.
saving space but wasting time and echant. i've done this kind of theoritical thing many2 years ago on plumbing system.
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Online tautech

  • Super Contributor
  • ***
  • Posts: 16324
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
Re: Trace Width along the path to next component
« Reply #10 on: September 04, 2014, 11:26:21 pm »
I asked this, because I was trying to save circuit board space.
saving space but wasting time and echant. i've done this kind of theoritical thing many2 years ago on plumbing system.
And Tradesman plumbers from another era always did this.
The best still do.
I have many Km's of piping on my farm and the main piping runs are all large with small feeders supplying the individual loads/troughs.
Electrical mains supply networks are no different.
PCB's often have power planes....the same principle applies, does it not?
When needed, it is good design IMO.
Avid Rabid Hobbyist
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf