>At 04:56 PM 12/3/96 +0100, Martin Nilsson wrote:
>>Ben L Wirz wrote:
>>
>>>         You have used the L293D or the L293 to 1 Amp?  The L293 is rated
>>> at .6 A and the L293D is rated at 1 Amp, or they can be bridged for
>>> double capicity.  Can I also ask where you found the L293's if thats what
>>> you used, I haven't been able to find them in anything less then 200 min
>>> order.
>>
>>I'm afraid you should not try to increase the current capacity by
>>paralleling outputs of bipolar devices, such as the 293. If you do,
>>the maximum allowable current will be not be the sum, but the minimum
>>of the individual maxima.
>>

<snip sensible comments about blowing things up>

I have used a lot of different H-Bridges over the years and would
definately NOT run any in parallel.

It is far easier and cheaper in the long run to get a higher spec device
there are lots around...

the best of those that I have used are:-

        1. MPM3002  motorola keeps dropping them and then re-instating.
                    otherwise unbeatable for high current 8A 100V

        2. IR8200B  IR part that nat semi now makes an exact equivalent
                    is also excellent. Pretty well
                    indestructable if you watch out for voltage spikes
                    50v 3A, but i have run at 5-6A for short periods.

        3. L6203    sgs no thermal overload or I sense outputs but
                    if you can add these externally good for 48V 5A.

        4. discrete fets with hi-side drivers are generally required
           if you want to go much above 50v or so. IR2110's and any
           suitably rated N-channel fets x4.

Most failures of these devices IMHO are caused by voltage spikes, snubbers
transorbs mov's whatever you can do to kill those fast transients will
prolong the device life.



Ray Gardiner, Shepparton, Victoria, Australia       ray@dsp-systems.com
Technical Director DSP Systems               http://www.dsp-systems.com
Private e-mail to:-  ray@netspace.net.au