Paralleling LMD18200T

[Abe]

Hi,
I have been using the National's LMD18200Ts for about a year for
motors requiring low currents (<2A). Now I need to use these for
motors pulling something like 6A. There is one post somewhere
mentioning that this IC can be paralleled. But does anyone have
practical experience regarding this?
Any information would be helpful.
Thanks,
Abhijit Karnik

 

[Lewin A.R.W. Edwards]

I have been using the National's LMD18200Ts for about a year for
motors requiring low currents (<2A). Now I need to use these for
motors pulling something like 6A. There is one post somewhere
mentioning that this IC can be paralleled. But does anyone have

It seems straightforward enough, the only thing that would worry me is
the possibility that - briefly - during direction changes, one device
might change states a little slower than the other, which would
momentarily short the power rails through both sets of drivers. Maybe
it would be safer to go through a brief unpowered state (PWM low,
BRAKE high) when changing directions.

 

[Tim Wescott]

I concurr. Shoot-through is nasty.

Depending on your particular requirements you may also want to consider
using a controller and discrete MOSFETs or the APEX power drivers (I think
they go up to 6A). APEX parts are spendy and they don't cover the whole
applications area, but when they work they'll save you engineering time. A
controller and discrete FETs, on the other hand, will have a lower
manufacturing cost but has the potential to absorb many hours of debug time
before you can allow your design to escape to the manufacturing floor.

"Lewin A.R.W. Edwards" <larwe@larwe.com> wrote in message
news:608b6569.0312301138.6658edf4@posting.google.com...

I have been using the National's LMD18200Ts for about a year for
motors requiring low currents (<2A). Now I need to use these for
motors pulling something like 6A. There is one post somewhere
mentioning that this IC can be paralleled. But does anyone have

It seems straightforward enough, the only thing that would worry me is
the possibility that - briefly - during direction changes, one device
might change states a little slower than the other, which would
momentarily short the power rails through both sets of drivers. Maybe
it would be safer to go through a brief unpowered state (PWM low,
BRAKE high) when changing directions.