LTC3887 RUN pin voltage concerns

Hi,

This is Yu.

Now we are using LTC3887 as SMPS controller in our design, and I have some concerns about this pin.

To achieve the power sequence requirement of the system,

We are using the 1.8V(generate from other output) to pull-up this pin instead of VDD33 which is generated by LTC3887 itself.

 

And I have already check the power-up sequence waveform of the design, and the Vih of the RUN pin (1.35V Max). the design should be fine.

 

But the description in the LTC3887 datasheet confused me that the RUN pin should be pull-up by 3V3.

I want to make sure 3V3 is mandatory or I can still use the voltage larger than 1.35V to drive this RUN pin.

Please help me clarify this

Thanks,

Yu

 

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