LM96063: ALERT and TCRIT active PWM genrates short impulse

Sebastian Ciesluk80

Part Number: LM96063

Hi I have built 3 boards ( prototyping ) where LM96063 are used , though I have no accecc to I2C on these boards yet and can only verify power on bahaviour.

I observe different behavious of LM9603, on one board it behaves correctly , PWM resets to low, TCRIT, ALERT = inactive but two other boards behave differently:

PWM after power up genrates short low pulse , then stays high and TCRIT and ALERT are both active.

Is this a known state of LM96063 indicating an error?

Asking as measurements are quite difficut around the chip so maybe I mange to get some pointer from you?

Thanks

Sebastian

over 5 years ago

0 David Vaseliou over 5 years ago

TI__Expert 6820 points

Hi Sebastian,

This sounds to be expected behavior.

As mentioned in the datasheet, "If at any time the TCRIT output were to activate the PWM duty cycle will be instantaneously forced to 100% thus forcing the fans to full on".

Thanks,

David

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Hi David,

Thanks a lot for the answer, I will try to go deeper into this as I think my case is not as the describtion in the data sheet..

All 3 boards I have are tested with and without fan connected and one of them always behaves correctly so PWM on and ALERT and TCRIT inactive.

The other two have just a pulse on PWM and both ALERT and TCRIT active, so it wonder what activates ALERT and TCRIT is it an error code ?, and why PWM does not stay fully on but ends up just wth short pulse?

Sebastian

0 David Vaseliou over 5 years ago in reply to Sebastian Ciesluk80

TI__Expert 6820 points

Hi Sebastian,

When you get I2C access can you please read the status, local temperature, and remote temperature registers?

Thanks,

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Thanks for the answer, I hoped you could deduct something withoput I2C access, the board I am working on is a bring up board for new processor so I need to try to get things resolevd before I got the main processor.

Sebastian

0 David Vaseliou over 5 years ago in reply to Sebastian Ciesluk80

TI__Expert 6820 points

Sebastian,

Debugging this can be a little hard without I2C communication. Can you send me your schematic and Oscilloscope waveforms of the D+ pin from one of the working boards and another from the board that has the alerts triggered.

Thanks,

David

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

David

David please find waves for good and bad boards, on the schematicside , can I send you these as email?

Thanks

Sebastian

0 Sebastian Ciesluk80 over 5 years ago in reply to Sebastian Ciesluk80

Expert 1121 points

Looks like the wave of good board gone missing in previous post so here it is :

Sebastian

0 David Vaseliou over 5 years ago in reply to Sebastian Ciesluk80

TI__Expert 6820 points

Hi Sebastian,

Can you check with a DMM continuity of your remote? It looks like the remote maybe shorted or opened. If that is not the issue can you send me your schematic?

Thanks,

David

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Hi David,

Thanks

I have checked continuity : high resistance both directions, soldered new transitor , contnuity test is fine but the behavior the same.

Happy to send you schematics , can you give me an email

Sebastian

0 David Vaseliou over 5 years ago in reply to Sebastian Ciesluk80

TI__Expert 6820 points

HI Sebastian,

Can you gather new waveforms with the new transistor? Also please personal message me to send schematic.

Thanks,
David

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Hi David

Thanks ,

To be fully precise I have connected second transistor without unsolderingteh first one , so righ now I have two in parallel, wave below.

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Thans David,

To be fully precise , I have soldered new transistor in parallel to first one so I have two right now .

The waveform below:

0 David Vaseliou over 5 years ago in reply to Sebastian Ciesluk80

TI__Expert 6820 points

Sebastian,

Can you please desolder the transistor that was giving high resistance both ways first and then keep the new transistor soldered down? I would like an exact A to B comparison between a working board and the nonworking board.

Thanks,

David

0 Sebastian Ciesluk80 over 5 years ago in reply to David Vaseliou

Expert 1121 points

Sure , Just searching how to send you private message?

0 Sebastian Ciesluk80 over 5 years ago in reply to Sebastian Ciesluk80

Expert 1121 points

Ok desoldered the original transistor and it started to work!

Thank you very much David, you were very helpful and I have problem solved !

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LM96063: ALERT and TCRIT active PWM genrates short impulse