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LM5022: What LM5022 consumption and efficiency

Johnson Pi
Intellectual 470 points
Part Number: LM5022
Other Parts Discussed in Thread: TPS61200

Hi!

I am using LM5022 to boost voltage from 2.5V into 6V. In order to have this IC stably operate, I introduce a external bias 10V but this bias supply is very limit from our system. I would like to know for the normal operation, how much input current (on 10V line) from Vin of the IC?

If possible, on the this operation way, how much the efficiency I can expect?

Thank you very much in advance

Johnson

  • 0
    TI__Guru 58721 points
    Hello
    Ivin can be approximately calculated by Ivin=3.5m + 1.2/RT+ Qg*Fsw where Qg is the gate charge of the MOSFET.
    Thanks
  • 0 in reply to EricLee
    Intellectual 470 points
    Hi! Eric Lee,

    I have new questions.

    My application is to use external bias (5V) for LM5022 and fairly set up UVLO in order for the control to work at 5V. My input mini voltage is 0.34V and output targeted voltage is 2.5V. Now I got problem for when voltage in the range between 0.34V to 1.2V, the output voltage is 1.8V to 2.2V. Under this condition, the load is very low (100mA). Is it problem for IC/LM5022 to work in this voltage range 0.34V to 1.2V?

    Thank you very much!

    Johnson
    949-290-8353
  • 0 in reply to Johnson Pi
    TI__Guru* 78260 points
    For such low voltage application, why not consider TPS61200 boost converter with integrated FET?
  • 0 in reply to Youhao Xi
    Intellectual 470 points

    Hi! Youhao Xi,

    My application  is for solar cell and with high output current (normally 8A to max 10A). Do you have other suggestion?

    I believe you suggest a good part but not for this application. I will consider it for low voltage input bias power source.

    Thank you very much!

  • 0 in reply to Johnson Pi
    TI__Guru* 78260 points
    By doing a quick calculation you can see the required output rectifier current (which is also the current passing through the inductor, main switch and current sense resistor) will be >80A in order to deliver 10A load current. Therefore these parts need to be very low resistance such that they won't eat up the 0.34V input voltage for power transfer. If you assume 1mOhm each, namely 1mOhm Rdc ofthe inductor, 1mOhm Rdson of the MOSFET, and 1mOhm of the current sense resistor, they would cause 0.24V voltage drop out of your 0.34V input. You effective input voltage is now only 0.1V, and the input current can be a few hundred amps... This does not appear practical. Can you reconfigure your solar cells in series such that the min voltage can be higher?