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LM2700 Simulation

Sivaraman Radhakrishnan
Prodigy 130 points
Other Parts Discussed in Thread: LM2700

Hi,

I have chose LM2700 WEBench Designer for 2.3V VIN minimum and maximum, 9.3V VOut and 230mA . i have used high efficiency mode.

What are all the parameters will impact when i use the same circuit component with 4.6V VIN.

I have attached the circuit for reference.

Thanks,

Sivaramanwebench_design_1191377_31_566428851 (1).pdf

  • 0
    TI__Mastermind 31580 points
    Hi Sivaraman,

    This post belongs in the non-isolated forum I will move it and one of my colleagues will pick it up there.

    Regards

    Peter
  • 0
    TI__Intellectual 2010 points

    Hi Sivaraman,

    There are a number of parameters that change if you increase the input voltage from 2.3V to 4.6V. I will try and list all of them in this post:

    1.  If you are operating at 1.2MHz or even 600kHz, the efficiency will improve significantly at 4.6V as the following plot shows:

      This is considering that your output voltage is 9.3V as you indicated in the attachment. If you increase the output voltage level, the higher input can negatively impact the efficiency. 

    2. Switching current limit changes as you change the input/output voltage range as shown in plot below:

    3. Third main differnence in parameter will be RDSON of internal FETs. The RDSON losses are significantly smaller at higher input voltage.  (Fig 9 datasheet). At 2.2V RDSON is ~120mohm (2A switching current) compared to only 60mohm at 4.6V under same conditions. 
    4. At 4.6V the switching and non-switching IQ incleases by very small margin.(Fig 12, 13)
    5. Finally the switching frequency accuracy is positively effected at higher input voltage. Please see the following fig:

    For more detailed plots, please refer to datasheet typical application graph 8 to 16. 

    Hope this helps.

    Best,