l6480 over current detection

[jitendra suthar]

Posted on June 21, 2017 at 09:10

hello

I am driving bipolar stepper motor using l6480. everything is fine motor is running excellent but the over current detection feature is working unpredictably. i have been disabled this feature then motor is working good, and there is confusion about the calculations of current threshold. in 'AN4355 Application note' it is written that 'IOCDth = VOCDth × Rds(ON)' which is contradicting the statement of datasheet of l6480, which says ' The L6480 measures the load current of each half-bridge sensing the VDS voltage of all the Power MOSFETs (Figure 12). When any of the VDS voltages rise over the programmed threshold'. i want to understand this OCD feature.

[Patrizia BELLITTO]

Posted on June 21, 2017 at 10:32

Hello,

sorry but this is not the correct place for your question, try to move it in the correct forum.

Patrizia

[Ehsan Daneshvar]

Posted on June 24, 2017 at 19:53

when a over current error happens? in some cases in could because of voltage spikes of motor, so a suitable snubber circuit could helps.

[jitendra suthar]

Posted on June 25, 2017 at 05:16

Hello sorry 

 Its by mistake Patrizia bellitto.

[jitendra suthar]

Posted on June 25, 2017 at 05:20

Thanks Ehsan Daneshvar

 I m confused about the equation written in application note. Which is described above.   

[Ehsan Daneshvar]

Posted on June 28, 2017 at 09:38

please say me exactly what part of that equation is not clear ? .. when you choose a suitable Power MOSFET . that MOSFET has a specific value of RdsOn .for example about IRFP250 this value is 0.085 Ohm .. ( when mosfet is Completely On ) .. so it resistance of Drain to Source is 0.085 Ohm .. by reading the voltage of Drain to source and according to OHM law you can calculate the current value ..

so according to application note and datasheet you should select correct

threshold .