Re: [CAD_CAM_EDM_DRO] Re: Updated website

On Sat, 20 Apr 2002 00:11:14 -0000, you wrote:

>I'm not real comfortable with FET's, but the transister
>portion of your H-bridge does not look right to me.

I'm reasonably comfortable that the bridge is right.

>The outputs of the L297 are TTL voltage levels between
>0 and Vcc (5 volts.) When the output A of the L297 is
>high, Q13 turns on, but Q1 is likely to be on as well.
>In order turn Q13 off, the output would have to get
>awfully close to Vs, which is likely greater than 20
>volts. With the current bridge design, I think you
>will have "shoot through" where both FET's turn on at
>the same time and let all the magic smoke out.
>
>The INH1* and INH2* pins on the L297 are outputs and
>should not be grounded. I doubt you really need to
>bother with either of these pins.

Damn - you right - I told you I needed help with this :)

>Lastly, I can't figure out what condition the diodes
>D2-D9 are trying to protect against.

Explained eloquently by Mariss <G>

>I hate to say it, but I think there is some more design work
>needed. Unfortunately don't have enough experience to
>propose alternative solutions.

Perhaps I should be looking for alternatives to the L297? Dunno! Spent
another hour trawling the allegro site this morning - but I'm even
more confused :(

Steve Blackmore
--
Pilot Consultancy Limited ***** Computer Consultants
Telephone 01744 752256 Mobile 07831 768478
Email: steve@... WWW: http://www.pilotltd.net