Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Current spikes destroy L298?

Status
Not open for further replies.

danijel.gorupec

Newbie level 4
Joined
Mar 14, 2011
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,345
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

Advanced Member level 5
Joined
Jan 20, 2011
Messages
3,562
Helped
1,262
Reputation
2,530
Reaction score
1,253
Trophy points
1,393
Activity points
26,775
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

Newbie level 4
Joined
Mar 14, 2011
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,345
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

Banned
Joined
Jun 22, 2008
Messages
1,180
Helped
37
Reputation
74
Reaction score
23
Trophy points
1,318
Activity points
0

mtwieg

Advanced Member level 5
Joined
Jan 20, 2011
Messages
3,562
Helped
1,262
Reputation
2,530
Reaction score
1,253
Trophy points
1,393
Activity points
26,775
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.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top