TLE9183QK What is SCD filter- and the SCD blank time?

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kangsenliu
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5 replies posted 5 questions asked 10 sign-ins

 Hey,friends.

   now i am working with tle9183,about its  Short Circuit Detection protion.   Now I want to know what SCD filter- and the SCD blank time means , what is the function of it. 

   A description of this is in the following picture.The default values for SCD filter-time  is 3.8 us .The default values for SCD blanking-time  is 2 us. Whether bigger is better in the value?

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1 Solution
Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi, Kangsen

It's hard to say it's better or not. 

Short circuit will not be detected if a duty cycle range at the external FET is applied which is shorter than the SCD filter- and the SCD blank time.

This means a short circuit shunt down takes longer than tfilter+tblank.

However, if the time is set too short. Then the device may shunt down for a transient current spike. 

So, customer can adjust these time depends on their application scenario.

Regards,

Xiangrui

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5 Replies
Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi, Kangsen

It's hard to say it's better or not. 

Short circuit will not be detected if a duty cycle range at the external FET is applied which is shorter than the SCD filter- and the SCD blank time.

This means a short circuit shunt down takes longer than tfilter+tblank.

However, if the time is set too short. Then the device may shunt down for a transient current spike. 

So, customer can adjust these time depends on their application scenario.

Regards,

Xiangrui

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hey,my friend.

  Sincerely thanks a lot for your reply.  The problem now is that when I run the motor normally, the short-circuit detection in the test software often gives an occasional error. I think what should I do without changing the short-circuit detection threshold and changing blanking time and filter time

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Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi Kangsen,

If you don't want to change threshold and filter time, then the hardware has to be changed for reduce the current spike.

Further more, changing the control method can also be an alternative way, like reduce the motor rate change. However, I think it is even complex than changing the filter time.

Regards,

Xiangrui

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hey,my friend.

   Just like what you say.If i can  increase the filter time appropriately to reduce this kind of occasional error.

  • For example, I changed the default value 3.8 Subtle to 5.8 microseconds

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Xiangrui
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi Kangsen,

It depends on the duration of the spike. If it takes only 4ms, then it will be solved by increasing filter time. 

But if it takes 10 ms, then it won't.

Regards,

Xiangrui