LTC7840 and the DC2744 demo board

Greetings.

I have an application that it appears the LTC7840 would work well for.

LTC7840 Data Sheet

I have a supply of 5.5V to 32Vdc and need an output of 280V.    Using the 7840 as a two stage with the first stage handling the wide input range and the second stage handing the large step-up seems like a solid plan.   ADI has a demo board (DC2744) that demonstrates this. 

DC2744 Link

The differences are:

1) The DC2744 does 9 to 36V input.  I need to get down to at least 6V input.

2) The DC2744 output is 240V and I need 280V.

3) On the bright side I need only 200mA and the DC2744 provides 700mA. 

What do I need to do to get the DC2744 to work down to 6V instead of 9V?

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  • 0
    •  Analog Employees 
    on Dec 13, 2018 6:45 AM

    Hi Keith 

    You can used the equations under the Shutdown and Start-Up section of the datasheet for modifying the input threshold. 

    I would just like to remind you to check if the ratings of the components (e.g. Mosfet max ID...) and limitations of the controller (e.g. DMAX, tON(MIN)...) can handle changes in the input and output of the converter  before powering it. 

    Regards,

    Mikee

Reply
  • 0
    •  Analog Employees 
    on Dec 13, 2018 6:45 AM

    Hi Keith 

    You can used the equations under the Shutdown and Start-Up section of the datasheet for modifying the input threshold. 

    I would just like to remind you to check if the ratings of the components (e.g. Mosfet max ID...) and limitations of the controller (e.g. DMAX, tON(MIN)...) can handle changes in the input and output of the converter  before powering it. 

    Regards,

    Mikee

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