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Questions regarding L9906 (FET Driver for 3-ph BLDC Motor)

Question asked by Oliver Dieterle on Aug 1, 2017

Hello all,

 


I'm working here with the "L9906CB".
I have some questions regarding the functionality of the IC, which I could not clarify by looking into the datasheet (this is the only document I could get for this IC) or via other topics in the forum.

The questions are:
1) The L9906 has a shoot through protection functionality. In our case, the value for the duration of the shoot through protection is always set to 100-200 ns. Until now, I had the feeling that the L9906 adds this 100-200 ns ON TOP of the dead time of my switching signals, which are the input signals for the L9906. Is that correct?
Furthermore I have the question: The declaration of 100-200 ns from the datasheet still give still a range for the duration of this additional dead time. I want to quantify the real dead time, which I have in my PWM. And I don't know now, which is the value that is added exactly. Could you help me also with this issue?
2) The second point is: Using the L9906, is it possible to activate a Highside-MOSFET and/or a Lowside-MOSFET for a "long" period of time, i.e. not to use a PWM in this time but just activate one of the switches? My concern here is, that this could affect the functionality of the Boost-Converter for the switching of the Highside-FET.... Or is this not a problem at all?

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