Isolating power supplies with L298

Isolating power supplies with L298

Post by Stephane Gauthie » Thu, 22 Mar 2001 06:01:18



Hi all,

I've been using an L298 as my motor controller on my bot and I've always
been sharing the ground between my 6V SLA battery (for the motors) and
my 5V source.  Today I was thinking about replacing the 4 control lines
from the CPU to the L298 with opto-isolators but then I remembered that
the L298 requires two voltage sources so I guess I'm stuck right?  I
believe there has to be a difference of around 1-2v between Vsupply and
Vcc on the L298.

How do people normally isolate their power sources?

thanks in advance,

--------
http://robots.dns.org

--
=================
Stephane Gauthier
Firmware Designer

Alcatel CID
600 March Road, P.O. Box 13600
Kanata, Ontario, Canada K2K 2E6

Phone: 613 784 1387
fax:   613 599 3639

  stephane.gauthier.vcf
< 1K Download
 
 
 

Isolating power supplies with L298

Post by Paul Jurcza » Thu, 22 Mar 2001 10:21:05


Stephane,

  there is no need to separate grounds, if you generously use
decoupling
capacitors. Specified logic supply for L298 is 4.5V to 7V and power
supply is 4.8V to 46V, so you could use single power source for both.
Usually you use unregulated battery voltage for power and 5V regulated
(linear voltage regulator) for logic.

--
Paul Jurczak


> Hi all,

> I've been using an L298 as my motor controller on my bot and I've
always
> been sharing the ground between my 6V SLA battery (for the motors)
and
> my 5V source.  Today I was thinking about replacing the 4 control
lines
> from the CPU to the L298 with opto-isolators but then I remembered
that
> the L298 requires two voltage sources so I guess I'm stuck right?  I
> believe there has to be a difference of around 1-2v between Vsupply
and
> Vcc on the L298.

> How do people normally isolate their power sources?

> thanks in advance,

> --------
> http://robots.dns.org

> --
> =================
> Stephane Gauthier
> Firmware Designer

> Alcatel CID
> 600 March Road, P.O. Box 13600
> Kanata, Ontario, Canada K2K 2E6

> Phone: 613 784 1387
> fax:   613 599 3639



 
 
 

Isolating power supplies with L298

Post by Stephane Gauthie » Fri, 23 Mar 2001 02:01:40


I see. I've been using exactly that: unregulated 6V SLA for motors and
regulated 5V for logic.
I'll pepper my board with some more of those dec. caps then.

Thanks,


> Stephane,

>   there is no need to separate grounds, if you generously use
> decoupling
> capacitors. Specified logic supply for L298 is 4.5V to 7V and power
> supply is 4.8V to 46V, so you could use single power source for both.
> Usually you use unregulated battery voltage for power and 5V regulated
> (linear voltage regulator) for logic.

> --
> Paul Jurczak



> > Hi all,

> > I've been using an L298 as my motor controller on my bot and I've
> always
> > been sharing the ground between my 6V SLA battery (for the motors)
> and
> > my 5V source.  Today I was thinking about replacing the 4 control
> lines
> > from the CPU to the L298 with opto-isolators but then I remembered
> that
> > the L298 requires two voltage sources so I guess I'm stuck right?  I
> > believe there has to be a difference of around 1-2v between Vsupply
> and
> > Vcc on the L298.

> > How do people normally isolate their power sources?

> > thanks in advance,

> > --------
> > http://robots.dns.org

> > --
> > =================
> > Stephane Gauthier
> > Firmware Designer

> > Alcatel CID
> > 600 March Road, P.O. Box 13600
> > Kanata, Ontario, Canada K2K 2E6

> > Phone: 613 784 1387
> > fax:   613 599 3639


--
=================
Stephane Gauthier
Firmware Designer

Alcatel CID
600 March Road, P.O. Box 13600
Kanata, Ontario, Canada K2K 2E6

Phone: 613 784 1387
fax:   613 599 3639

  stephane.gauthier.vcf
< 1K Download
 
 
 

Isolating power supplies with L298

Post by Paul Jurcza » Fri, 23 Mar 2001 10:21:12


 Stephane,

You may run into problems, if you use 6V battery as an input
for 5V voltage regulator. Discharged battery will give you
about 5V output, which is not enough for voltage regulator.

--
Paul Jurczak


> I see. I've been using exactly that: unregulated 6V SLA for motors
and
> regulated 5V for logic.
> I'll pepper my board with some more of those dec. caps then.

> Thanks,


> > Stephane,

> >   there is no need to separate grounds, if you generously use
> > decoupling
> > capacitors. Specified logic supply for L298 is 4.5V to 7V and
power
> > supply is 4.8V to 46V, so you could use single power source for
both.
> > Usually you use unregulated battery voltage for power and 5V
regulated
> > (linear voltage regulator) for logic.

> > --
> > Paul Jurczak


message

> > > Hi all,

> > > I've been using an L298 as my motor controller on my bot and
I've
> > always
> > > been sharing the ground between my 6V SLA battery (for the
motors)
> > and
> > > my 5V source.  Today I was thinking about replacing the 4
control
> > lines
> > > from the CPU to the L298 with opto-isolators but then I
remembered
> > that
> > > the L298 requires two voltage sources so I guess I'm stuck
right?  I
> > > believe there has to be a difference of around 1-2v between
Vsupply
> > and
> > > Vcc on the L298.

> > > How do people normally isolate their power sources?

> > > thanks in advance,

> > > --------
> > > http://robots.dns.org

> > > --
> > > =================
> > > Stephane Gauthier
> > > Firmware Designer

> > > Alcatel CID
> > > 600 March Road, P.O. Box 13600
> > > Kanata, Ontario, Canada K2K 2E6

> > > Phone: 613 784 1387
> > > fax:   613 599 3639

> --
> =================
> Stephane Gauthier
> Firmware Designer

> Alcatel CID
> 600 March Road, P.O. Box 13600
> Kanata, Ontario, Canada K2K 2E6

> Phone: 613 784 1387
> fax:   613 599 3639


 
 
 

Isolating power supplies with L298

Post by Stephane Gauthie » Sat, 24 Mar 2001 01:43:24


I know. I meant a 6V battery for the motors. And another 9v battery
regulatred to 5v for logic.

Take care,


>  Stephane,

> You may run into problems, if you use 6V battery as an input
> for 5V voltage regulator. Discharged battery will give you
> about 5V output, which is not enough for voltage regulator.

> --
> Paul Jurczak



> > I see. I've been using exactly that: unregulated 6V SLA for motors
> and
> > regulated 5V for logic.
> > I'll pepper my board with some more of those dec. caps then.

> > Thanks,


> > > Stephane,

> > >   there is no need to separate grounds, if you generously use
> > > decoupling
> > > capacitors. Specified logic supply for L298 is 4.5V to 7V and
> power
> > > supply is 4.8V to 46V, so you could use single power source for
> both.
> > > Usually you use unregulated battery voltage for power and 5V
> regulated
> > > (linear voltage regulator) for logic.

> > > --
> > > Paul Jurczak


> message

> > > > Hi all,

> > > > I've been using an L298 as my motor controller on my bot and
> I've
> > > always
> > > > been sharing the ground between my 6V SLA battery (for the
> motors)
> > > and
> > > > my 5V source.  Today I was thinking about replacing the 4
> control
> > > lines
> > > > from the CPU to the L298 with opto-isolators but then I
> remembered
> > > that
> > > > the L298 requires two voltage sources so I guess I'm stuck
> right?  I
> > > > believe there has to be a difference of around 1-2v between
> Vsupply
> > > and
> > > > Vcc on the L298.

> > > > How do people normally isolate their power sources?

> > > > thanks in advance,

> > > > --------
> > > > http://robots.dns.org

> > > > --
> > > > =================
> > > > Stephane Gauthier
> > > > Firmware Designer

> > > > Alcatel CID
> > > > 600 March Road, P.O. Box 13600
> > > > Kanata, Ontario, Canada K2K 2E6

> > > > Phone: 613 784 1387
> > > > fax:   613 599 3639

> > --
> > =================
> > Stephane Gauthier
> > Firmware Designer

> > Alcatel CID
> > 600 March Road, P.O. Box 13600
> > Kanata, Ontario, Canada K2K 2E6

> > Phone: 613 784 1387
> > fax:   613 599 3639


--
=================
Stephane Gauthier
Firmware Designer

Alcatel CID
600 March Road, P.O. Box 13600
Kanata, Ontario, Canada K2K 2E6

Phone: 613 784 1387
fax:   613 599 3639

  stephane.gauthier.vcf
< 1K Download
 
 
 

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