LM7480-Q1: Time delay for output generation

Nandini Muralidharan

Part Number: LM7480-Q1

Tool/software:

Hi,

I have this configuration and would like to know what the time delay between the input side 12V to generation of combined 12V at the source of the mosfet.

Can you explain how it needs to be calculated and what are all the parameters to include in this calculation?

Thanks

2 months ago

0 Shiven Dhir 2 months ago

TI__Mastermind 21740 points

Hi Nandini,

First, charge pump needs to reach its UVLO which will take some time to charge.

Second, the bulk cap will take time to charge when inrush current is controlled. Where 12 is the final voltage.

Regards,

Shiven Dhir

0 Nandini Muralidharan 2 months ago in reply to Shiven Dhir

Intellectual 710 points

Hi Shiven Dhir,

As suggested we have calculated charging time for Charge pump and we are getting 428mS. Considered 100nF for C(cap). Which means this device will take at least 428mS to enable the output voltage?

But our requirement is the time delay between input and output should be less than 5ms, Could you please advise how to achieve this...

0 Shiven Dhir 2 months ago in reply to Nandini Muralidharan

TI__Mastermind 21740 points

Hi Nandini,

Charge time with 100nF C(cap) will be ~420uS and not ~420ms.

Rest, the time it takes for VOUT to reach 12V depends on load capacitor and limited inrush current.

Regards,

Shiven Dhir

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LM7480-Q1: Time delay for output generation