LMH0397: power on reset

Hi,

Why are they powering down to and powering up from 1V? Do they see issue if power up/down from 0V to 2.5V?

Thanks

David

Hi

This is becuase FET placing on VIN power line turned off simply while shut down without VIN pull down circuitry. in this case, VIN seems to keep 1V when LHM0397 shutdown. Eventually the system power up from VIN=1V.

 I do not think any issue was hannepned when he start up from 0V to 2.5V yet, can you tell us if such a power up is acceptable ?
If not, can you also tell us why ?

regards,

Hi,

So the LMH0397 is not fully powered on or off. If you look at the LMH0397 recommended operating condition, VIN is min of 2.375V and max of 2.625V. So 1V is outside of its recommended operating condition and we do not characterize the LMH0397 at 1V, so the LMH0397 behavior at 1V is not guaranteed.

Thanks

David

Hi

The customer issue was happened when VIN rised up to 2.5V from 1V. 2.5V VIN is the recommended operation but are there any isses expected when VIN is ramped from 1V to 2.5V ? 

Best regards,

Hi,

But LMH0397 is not fully power down and at 1V, its operation can't be guaranteed. If they ramp back to 2.5V, and then toggle the ENABLE pin, does LMH0397 then work correctly?

Thanks

David

Hi, 

Our cstomer has a question when LMH0397 start up from VIN=1V. Could you help him out what kind of issue or problem we are expecting if VIN ramp up from 1V.

best regards,

Hi,

1V is outside of its recommended operating condition and we do not characterize the LMH0397 at 1V, so the LMH0397 behavior at 1V is not guaranteed.

Thanks

David

Hi,

Thank you for your quick feedback.

Does that mean we cannot expect what will be happened in case a user had LMH0397 turned on from 1V VIN ?

I am personally thinking that VIN=1V is pretty unstable condition how it works which means HiZ state, so we usually cannot expect device function at all. This is I think the reason we usually recommend power up from 0V.

best regards,

Hi,

Does that mean we cannot expect what will be happened in case a user had LMH0397 turned on from 1V VIN ?

Correct. 1V VIN is outside of recommended operating condition, we can't expect the device to function correctly at 1V. 

Thanks

David