Sink or Source
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Posts: 46,084
Hi
Hope this is not a daft question.
Can some one provide for me a simple definition of what Sinking
Current or Sourcing Current is actually doing to an IC Output (eg
Stamp Output Pins) when it Sinks or Sources, then I can descide if I
should be Sinking or Sourcing?
Thanks
Hope this is not a daft question.
Can some one provide for me a simple definition of what Sinking
Current or Sourcing Current is actually doing to an IC Output (eg
Stamp Output Pins) when it Sinks or Sources, then I can descide if I
should be Sinking or Sourcing?
Thanks
Comments
Just think of sourcing as "supplying". In the source mode, the I/O
pin would supply the current to the device connected - example LED,
so that when the I/O pin was set to high, it would go to 5V and
supply the connected LED.
Sinking can be thought of as "receiving". In sink mode, the I/O pin
would receive the current from the connected device and route it to
ground, so when the pin was set to low, it would go essentially to 0V
and supply a route to ground to activate the device.
A simplistic explanation, but hopefully cleared up your question.
Regards, John.
--- In basicstamps@y..., Christopher_Hill@M... wrote:
> Hi
>
> Hope this is not a daft question.
>
> Can some one provide for me a simple definition of what Sinking
> Current or Sourcing Current is actually doing to an IC Output (eg
> Stamp Output Pins) when it Sinks or Sources, then I can descide if
I
> should be Sinking or Sourcing?
>
> Thanks
Sinking switches the ground for a device. (The device gets it's
power elsewhere)
> To: basicstamps@yahoogroups.com
> From: Christopher_Hill@M...
> Date: Wed, 18 Apr 2001 09:51:32 -0000
> Reply-to: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Sink or Source
> Hi
>
> Hope this is not a daft question.
>
> Can some one provide for me a simple definition of what Sinking
> Current or Sourcing Current is actually doing to an IC Output (eg
> Stamp Output Pins) when it Sinks or Sources, then I can descide if I
> should be Sinking or Sourcing?
>
> Thanks
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
A device is said to be either sinking or sourcing current, depending
upon which way the current flow is set up.
For example: If you set up a configuration wherein an NPN transistor
is connected with its emitter tied to dc ground, and its collector tied
to a motor, and the motor's other lead tied to the positive power supply,
you would say that the transistor is "sinking" current, as the flow is
going through the transistor to ground.
Another way of looking at it, would be for the transistor to be a PNP
type, and have its emitter tied to the positive rail and collector to the motor
lead. In this setup, the transistor is said to be "sourcing" the current to
the motor, since it itself is connected to the positive rail (the source).
Hope this cleared things up a bit.
Russ
Original Message
From: <Christopher_Hill@M...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, April 18, 2001 5:51 AM
Subject: [noparse][[/noparse]basicstamps] Sink or Source
| Hi
|
| Hope this is not a daft question.
|
| Can some one provide for me a simple definition of what Sinking
| Current or Sourcing Current is actually doing to an IC Output (eg
| Stamp Output Pins) when it Sinks or Sources, then I can descide if I
| should be Sinking or Sourcing?
|
| Thanks
|
|
|
|
| Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|
|
of times you do by varying the attached circuit - consider the following:
most microcontrollers, like the Stamp, can sink more current through their
pins, in aggregate, than they can source. I don't have the exact figures for
the Stamp at my fingertips - perhaps someone else does?
Michael.
Original Message
From: Christopher_Hill@M... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=a2RQKrNz4ckEJk_HEOaBp2qdIlxEk_-EeeirMG7enuXFaYgd56iWm7xtVCk8CSeMAf4-mMCRf5195OvpNeTxMPSsBA]Christopher_Hill@M...[/url
Sent: Wednesday, April 18, 2001 5:52 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Sink or Source
Hi
Hope this is not a daft question.
Can some one provide for me a simple definition of what Sinking
Current or Sourcing Current is actually doing to an IC Output (eg
Stamp Output Pins) when it Sinks or Sources, then I can descide if I
should be Sinking or Sourcing?
Thanks
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> pin would supply the current to the device connected - example LED,
> so that when the I/O pin was set to high, it would go to 5V and
> supply the connected LED.
>
> Sinking can be thought of as "receiving". In sink mode, the I/O pin
> would receive the current from the connected device and route it to
> ground, so when the pin was set to low, it would go essentially to 0V
> and supply a route to ground to activate the device.
This is what I tell my students. It will become a quiz question this week.
Paul
>Current or Sourcing Current is actually doing to an IC Output (eg
>Stamp Output Pins) when it Sinks or Sources, then I can descide if I
>should be Sinking or Sourcing?
>
Here's a simple working definition, summarizing the previous posts:
Assume a Stamp I/O pin is set as an Output.
The pin can be set either High (+5V), or Low (0V, "ground").
If the pin is set High, it acts as a current "source", supplying current to
whatever external circuitry it's attached to.
If the pin is set Low, it acts as a current "sink", basically providing a
"ground" for whatever external circuitry it's attached to.
Example:
"Source"
Stamp Pin set High
/\/\/\/\/
>|----[noparse][[/noparse]ground]
470 ohms LED
"Sink"
Stamp Pin set Low
/\/\/\/\/
|<----[noparse][[/noparse]+5 volts]
470 ohms LED
In the source mode, the LED lights when the pin is set High.
In the sink mode, the LED lights when the pin is set Low.
Since you can operate the LED in either mode, the choice of sourcing or
sinking often depends on how much current is required. For many devices,
they can sink more current than they can source, which would lead you to
choose sink mode. Hope this helps.
steve
Steve Roberts: sroberts@s...
On Wed, 18 Apr 2001 john_trinca@h... wrote:
> Chris,
>
> Just think of sourcing as "supplying". In the source mode, the I/O
> pin would supply the current to the device connected - example LED,
> so that when the I/O pin was set to high, it would go to 5V and
> supply the connected LED.
>
> Sinking can be thought of as "receiving". In sink mode, the I/O pin
> would receive the current from the connected device and route it to
> ground, so when the pin was set to low, it would go essentially to 0V
> and supply a route to ground to activate the device.
>
> A simplistic explanation, but hopefully cleared up your question.
>
> Regards, John.
>
> --- In basicstamps@y..., Christopher_Hill@M... wrote:
> > Hi
> >
> > Hope this is not a daft question.
> >
> > Can some one provide for me a simple definition of what Sinking
> > Current or Sourcing Current is actually doing to an IC Output (eg
> > Stamp Output Pins) when it Sinks or Sources, then I can descide if
> I
> > should be Sinking or Sourcing?
> >
> > Thanks
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
email: lamont@a... WWW: http://www.serv.net
"...There's no moral, it's just a lot of stuff that happens". - H. Simpson