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LM3549: Current Setting &Standby state

T Kishi
Genius 4425 points
Part Number: LM3549


Hi

My customer has question.

①The calculation formula of ISET is described in the data sheet P10.
　Why is the calculation formula different depending on the current value?

②How can I judge that it has entered the standby state?

Best Regard

T kishi

  • 0
    TI__Mastermind 22745 points
    Hi Kishi,
    (1) This device has divided two kinds of linear relation ship between current register setting and output current. first step is reg 0-710 recording to output current 0-550mA, second step is from reg 710-1024 which recording to output current from 550mA-700ma,the second step has higher resolution.
    (2)I'm not very clear about the "How can I judge that it has entered the standby state", you mean you want to change the output current during standby state? I think you need to divide two steps to adjust the output current with different relationship.
    Sean
  • 0 in reply to Sean Zhou
    Genius 4425 points
    Hi Sean

    Thank you for reply.

    You are right.
    Customers are worried about cases where register settings are not reflected in Device.
    When it can not be confirmed that the standby state has been reached, when will the register setting be possible?

    Regard
    T Kishi
  • 0 in reply to T Kishi
    TI__Mastermind 22745 points
    Hi Kishi,
    I think you can refer to LM3549 datasheet page 6 for detail operation state. When it start up , it will enter into stand by mode. When works in Normal mode, Device returns to standby mode if all X_EN inputs are low for time period set by Time out register. So you can wait after time out , it will enter into stand by mode. You can write the EEPROM at this time. In your application , you will change EEPROM many times?
    Sean
  • 0 in reply to Sean Zhou
    Genius 4425 points
    Hi Sean

    I think that it will not write many times in this application.
    I will tell customers that there is no indicator to judge that they have already entered the STANABY state.

    Thank you for responding.

    Best Regard
    T Kishi