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LM5181: Power output

Santosh
Prodigy 70 points
Part Number: LM5181
Other Parts Discussed in Thread: LM5180

Hi there,

I want to design dual output dc to dc isolated converter

my input range is 12 - 65 volt and output1 DC : 5v@750 mA   output2 DC  : 5V@10 mA

I got design form web-bench for one output and i learnt from 5181 eval board by simply adding one more winding dual output design is possible.

so while studying I seen table which says output current varies with input voltage. i have attached that table here

my question

1. what this table about?

2. Does output current is not constant and really depend on input voltage?

3. I need continuous load current of 750 ma and 10 ma irrespective of input voltage is this possible with 5181 or any other device will support

  • 0
    TI__Mastermind 25590 points

    Santosh,

    The image did not attach properly. Please attach again and I'll take a look.

    In general, however, this device will regulate the output voltage. The output current will depend on the load.

    -Sam

  • 0 in reply to Samuel Jaffe
    Prodigy 70 points

    Hi Sam,

    I have connected my electronic circuit as load which will take variable current from 50 to 500 mA  depending on which circuit is active like communication and display.

    If i use linear regulator like 7805 output voltage will remain at 5V irrespective of input voltage varies in range from 7.5 to 30 V and output current i draw ( that can be as low as 10 ma to 1 Amp ).

    I want to replace 7805 with this design to extend input voltage till 65V.

    the following table shows different output current at different input voltage.

    We want output voltage stable 5V ( with allowable voltage regulation ) and output current can vary from no load to max load at any input voltage for range 12 to 65 V.

  • 0 in reply to Santosh
    Prodigy 70 points

    Hi Sam,

    I have connected my electronic circuit as load which will take variable current from 50 to 500 mA  depending on which circuit is active like communication and display.

    If i use linear regulator like 7805 output voltage will remain at 5V irrespective of input voltage varies in range from 7.5 to 30 V and output current i draw ( that can be as low as 10 ma to 1 Amp ).

    I want to replace 7805 with this design to extend input voltage till 65V.

    the following table shows different output current at different input voltage.

    We want output voltage stable 5V ( with allowable voltage regulation ) and output current can vary from no load to max load at any input voltage for range 12 to 65 V.

  • 0 in reply to Santosh
    TI__Mastermind 25590 points

    Santosh,

    1. That table is showing the maximum load current. This does not mean that the output will give you that current all the time. It means that the device will regulate an output voltage and will be able to provide an output current from 0A up to the specified current.

    2. Output current depends on the output voltage (which you set) and the load.

    3. Yes this is possible.

    -Sam

  • 0 in reply to Samuel Jaffe
    Prodigy 70 points

    Thanks Sam,

    From your reply it is not clear that following requirement is possible or not.

    Below is my requirement using LM5180 or LM5181 ( Isolated )

    Input voltage range of 10 - 65 V and output current is 750 mA at 5V DC.

    so required output is possible at given input voltage range of 10 V DC to 65 VDC ?

  • 0 in reply to Santosh
    TI__Mastermind 25590 points

    Santosh,

    Sorry for my delayed reply.

    Yes this is possible. LM5180 is rated up to 65VIN and has an internal FET rated for 1.5A. You can find reference designs and evaluations boards on the product page such as this EVM and this reference design which has multiple outputs.

    -Sam