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L298 driver spec says disable during power up and power down

In the ST data sheet for the L298 dual full bridge driver on page

7/13 it says

Turn-On andTurn-Off : Beforeto Turn-ONthe Sup- plyVoltageand beforeto TurnitOFF, theEnablein- put must be driven to the Low state.

Note: Low disables the outputs.

Is there some reason that I'm missing that makes this necessary, beyond perhaps not wanting to have the outputs momentarily yanking around?

I've tried reading the entire data sheet carefully to see if I can spot any reason for this requirement and I just don't see it.

Satisfying this constraint for power up isn't a problem but being ready for power off is a lot less convenient with what I'm doing. I'm driving a permanent magnet motor with this part.

Thanks

Reply to
Don Taylor
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Maybe prevention of shoot through when vcc is coming on? Or prevention of 'turn on thump' like in an audio amp? You decide if a 'twitch' on the throttle or whatever is being controlled is a problem.

Reply to
BobG

On Mon, 12 May 2008 19:23:33 -0500 in sci.electronics.design, Don Taylor wrote,

Only a guess, but I guess this is to prevent simultaneous turn on of the pull-up and pull-down transistors.

Reply to
David Harmon

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