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LM2623EV: startup voltage

Viktorija Cecil
Genius 17971 points
Part Number: LM2623EV
Other Parts Discussed in Thread: LM2623,

Team, 

Per LM2623 datasheet startup voltage is 1.1V.

Is LM2623EV board configured in a way to provide an output at that voltage?

My customer cannot get any output below 2.0V. Any input would be appreciated.

Thanks

Viktorija

  • 0
    TI__Mastermind 34201 points
    Hi Viktorija,

    There is no need to configure something on the EVM to get a Vout at 1.1V Vin.
    How does you customer supply the Vin? With a power supply or a battery? Is there a current limit at input voltage power supply?
    Have they check the board input terminator voltage?
  • 0 in reply to Zack Liu
    TI__Genius 17971 points
    Per customer: I am using a power supply. I set the current limit on the supply extremely high (6 amps). The inrush current at startup is huge. Looking at both voltage and current, the voltage output will climes slowly, while current input is holding around 1.7 amps. If the output reaches the correct value then the input current drops to less than 1mA. On low voltage inputs the current will hold steady at a high value but the output voltage never makes it to regulation.
  • 0 in reply to Viktorija Cecil
    TI__Mastermind 34201 points
    Hi Viktorija,

    Thanks for providing these information.
    I'll check the input inrush current during startup later on bench. Before that, I want to confirm two things with you:
    1. Is there any load at the output during startup?
    2. On low voltage inputs the current will hold steady at a high value but the output voltage never makes it to regulation.
    -What's the "low voltage input"? Do you mean 1.1V?
    I'll tell you once I get the startup waveform.
  • 0 in reply to Viktorija Cecil
    TI__Mastermind 34201 points

    Hi Viktorija,

    Please see below startup waveform in Vin=2V & Vin=1.2V condition.

    Vin=2V:

    (CH1: Vin, CH2: Vout, CH4: Iin)

    Vin=1.2V:

    (CH1: Vin, CH2: Vout, CH4: Iin)

    As you can see, the device could start up in both conditions. The input inrush current is not that high like customer said. Could they provide the key start up waveform?