Current spikes destroy L298?

[danijel.gorupec]

I use L298 dual H-bridge to drive a stepper motor. The L298 fails eventually (after few hours).

I see current spikes that happen at switching moments - up to 6A, 100ns (the datasheet for L298 says that maximum allowed spike is 3A, 100ns). The spike is, I suppose, product of parasitic capacity of stepper motor windings.

Can such spikes be responsable for L298 fail? If yes, what to do? (power supply is 30V, but inserting a 10ohm,10W resistor doesn't seem as a solution to me as it would decrease speed/acceleration of the stepper motor).

 

[mtwieg]

sounds like it could be shoot through current, which means there might not be enough dead time on the bridge. Do you see this current spike going through the load, or just through the H bridge?

 

[danijel.gorupec]

I see it through the load (I inserted a 1ohm resistor in series to load and I am measuring voltage over it using my scope).

(BTW, I know that two H-bridges inside single L298 can be paralleled to double capacity - but I don't know will this double its current-spike handling abilitiy.)

 

[eem2am]

hello,

my friend you are suffering from "reverse recovery" of the diodes in your L298

you should use "schottky" diodes

THERE IS GOOD APP NOTE ON THIS SITE FOR YOU. (sorry caps)

**broken link removed**

it is found under stepper driver ic section some where.

ok here it is.

2shared - download External_recirculating_diodes_APP_E[1].pdf

...please read as you wish and please tell of your result.

 

[mtwieg]

hello,

my friend you are suffering from "reverse recovery" of the diodes in your L298

you should use "schottky" diodes

Well the L298 doesn't seem to have internal diodes, and that you need to provide your own (or you should if you're driving inductive loads). Do you have external catch diodes on the bridge? If not, that may be your problem.