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REG71050: About out put rush current

Tsukui Yusuke
Guru 21930 points
Part Number: REG71050

Hi,

Could you tell me about REG71050 out put current spec.
Please check the attached waveform.

REG71050.pdf

1.The inrush current is 200 mA.
   Is this all right?

2.The RMS output current is 66.3 mA.
   Is this all right?

The recommended operation rated current value was not described in the data sheet.
Could you give me your advice?

Best Regards,

Yusuke Tsukui

  • 0
    TI__Mastermind 20900 points
    Hello Yusuke-san,

    1. this seems to be alright. Please crosscheck figure 20 from datasheet. What was the input voltage and load for this tests? Was the test done on the EVM or in a system? can you share the schematic?

    2. i am not sure how the rms is calculated in this scope.

    The output current is dependent on the input voltage. Check the "efficiency vs load" figure from the first page.

    regards,
    Julian
  • 0 in reply to Julian Hagedorn
    Guru 21930 points

    Julian-san,

    Thank you for your response.

    1.Evaluation is done by customer's system.
       I would like to send the customer's schematic to you.
       Can I email directly?
       My e-mail address is tsukui-y@macnica.co.jp
      
       "What was the input voltage and load for this tests?"
       →I have not got the information from the customer.
    　　  I'll check it and get back to you.
       
        "this seems to be alright."
       →Thank for your advice.
          Fig. 20 shows the input current.
          With this inrush current (≒200mA / 3.5 usec pulse), the device will not fail.
          Is my understanding correct?
         

    2.Thank you for you comment.
       Let me know one more thing.
    　What is the problem when the average current is larger than 60 mA?
    　The specifications of the output current max are not described in the electrical characteristics of the data sheet.
    　
    　

    Best Regards,

    Yusuke Tsukui

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 20900 points
    Hello Tsukui-san,

    please send the schematics to lbs_request@list.ti.com with the thread topic as subject.
    i will come back to your other questions tomorrow.

    regards,
    Julian
  • 0 in reply to Julian Hagedorn
    TI__Mastermind 20900 points
    Tsukui-san,

    1. this inrush current is a normal behavior. The output caps are basically charged. The device will detect the high current and limit it to the short circuit current (see figure 19). As soon the device reaches the desired VOUT and Iout is less then 60mA (depending on VIN) the device enters normal regulation.
    2. During startup the current is usually larger (limited to short circuit current) to charge the output caps.

    regards,
    Julian