LM62440-Q1: tEN time

Hi Tsuji-san,

From the datasheet, I see that tEN is:

I hope this answers your question.

Ben

Hi Ben-san,

I would like to know the min/max time to calculate the sequence. Conservative number is fine. Is it available?

Is there scope shot available to see EN signal and SW node or VOUT timing?

regards,

Hi Tsuji-san,

Below is a scope shot found in the datasheet.

Shinji Tsuji said:

I would like to know the min/max time to calculate the sequence. Conservative number is fine. Is it available?

The tEN is based on VCC startup time when its voltage surpasses the VCC_UVLO. I don't see a min/max for that spec in the datasheet. I would assume that the min/max for tEN is based on the capacitor placed on VCC.

Ben 

Hi Ben-san,

OK. I understand that tEN includes Vcc start up (Cvcc charge) time. 

Could you please check the design target value for min and max with given (1uF) Vcc cap?

regards,

Hi Tsuji-san,

Our testing shows that VCC_UVLO has a range of 3.57V @ -40C to 3.795V @ 125C.

Ben

Hi Ben-san,

I need a value of tEN min and max time for proper start up sequence of my system.

Could you please translate the VCC_UVLO variation to tEN min/max value?

regards,

Hi Tsuji-san,

I would ratio the tEN time by the info that I gave you. My thoughts are if VCC_UVLO at 3.6V gives 0.7mS, then at 3.57V, tEN will be 0.694ms and 3.795V will yield a tEN of 0.738ms.

Ben

Hi Ben-san,

Does VCC_UVLO include Vcc_Cap temp variation?

regards,

Hi Tsuji-san,

No, it does not.

Ben