LM5032: Double pulse on output pins 7&10

Hi Alain,

The issue is most likely related to some noise disturbing the internal DCL comparator within the IC which causes the pulsing on the falling edge of the gate drive. You could try increasing the decoupling capacitance on the Vcc pin of the IC and even add a small, 220pF across the DCL pin to see if the performance improves.

Regards

Peter

Hi Alain,

What feature are you trying to implement by controlling the duty cycle with the DCL pin? Normally the PWM duty cycle is controlled by the COMP pins and the gate drive waveform does not have this issue when controlled by COMP.

I think you may have to chose either to try to design around this limitation, or live with it. The double pulsing does not look very nice but does the double pulsing cause an issue in the application?

Regards

Peter

Hi Alain,

I hope you have made some progress in the meantime, since there has been no activity for a while I will close this post. Please open a new post if you have further questions.

Regards

Peter

Hi Peter , sorry I don't understand why you don't have my previous answer. I'm surprised that you have no issue to suppress this problem . We can't use this function, it's useful for many characteritics (saturation protection, dynamic load, high variation input voltage…). "220pF capacitor (up to 2,2nFtested )has no effect."
I have to put two RC filter on outputs 7&10 and a double driver mosfet . It becomes an "heavy expensive" solution.
Regards .
Alain

Hi Alain

I agree this feature of the part is not well behaved at certain operating condictions on the LM5032.

TI also makes the UCC28220, www.ti.com/.../UCC28220 which offers a similar feature set, maybe this may be of interest if the design is unable to support the solution that you implemented.

Regards

Peter

Hi Peter,
But we have only one PWM on UC28220 and not two like LM5032. for my application , I need one only . And I have to design a new PCB and I have no time more!
Regards
Alain

Hi Alain,

Sorry about the delay in responding to your post I was travelling on Business. The UCC28220 is also and interleaved controller like the LM5032 are you only using one output of the LM5032?

I appreciate it is annoying when you have already made the PCB, can you work around this behavior of the device?

Regards

Peter

Hi Alain,

I hope you have made some progress in the meantime, since there has been no activity on this post for a week I am closing this post.

If you have more questions please open a new post.

Regards

Peter