LM74900-Q1: Vout buildup time when EN = 'h'

Roy Chou1

Part Number: LM74900-Q1

Tool/software:

Hi Team.

I see below figure in datasheet. I would like to check how to calculate/estimate the duration of below arrows?

If condition is swapped. The Start-Up EN('H') with 12V Going Low to High, I would like to check how to calculate/estimate the Vout buildup time.

Regards,

Roy

0 Shiven Dhir 1 month ago

Hi Roy,

The VOUT ramp-up time depends on the inrush current limit branch.

We also have some delay due to VCAP buildup, which will enable both the GATEs

We have another propagation delay before turning HGATE ON of approximately 600 μs.

All this happens after EN high.

Regards,

Shiven Dhir

0 Roy Chou1 1 month ago in reply to Shiven Dhir

Hi Shiven,

T(DRV_EN) = 175us+ 0.1uF*6.6V/2.7mA = 415us.

Shiven Dhir said:
We have another propagation delay before turning HGATE ON of approximately 600 μs.

So it should be 415us+600us, it would be the first arrow that I show firstly?

How about the rise time on Vout?

Cout*Vout = I*t? How could we find I here if we use EVM circuit for an example?

Regards,

Roy

0 Shiven Dhir 1 month ago in reply to Roy Chou1

Hi Roy,

I is the inrush current.

Regards,

Shiven Dhir

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