Thread: PWM Signal
View Single Post
  #8   Spotlight this post!  
Unread 01-02-2014, 21:26
Ether's Avatar
Ether Ether is offline
systems engineer (retired)
no team
 
Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,101
Ether has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond repute
Re: PWM Signal

Quote:
Originally Posted by Dale View Post
It's feeding into an optoisolator in each Talon
Most likely so*. If there's a schematic, I haven't been able to find it.


Quote:
out of a 330 ohm resistor in the DSC
Yes. There's a schematic for this.


Quote:
The PWM output can source or sink 15ma.
With a dead short, yes.

Quote:
Most optoisolators turn on around 1.6ma
The spec is available for the Jag, and it is guaranteed to turn on with 1.6 ma.. Since there's a 150ohm series resistance and a voltage drop across the LED, it requires about 1 volt to push that 1.6 ma through the LED.

So if you drive 3 Jaguars being driven by one DSC PWM port:

5 - 330*i - (150/3)*i - 0.7 = 0 . . . => .. i=11ma .. => .. 3.8ma per Jag

So it should work for 3 Jags... but I'm not sure about that 0.7 number; couldn't find a spec.


Quote:
We've driven three Talons before with no issue but Mike might have thoughts about whether it's likely to be on the hairy edge.
If you're reading this Mike, any info you'd be willing to provide would be appreciated. Don't want to speculate.


* http://www.chiefdelphi.com/forums/showpost.php?p=1127215&postcount=3