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TPS61291: TPS61291

Rahul
Expert 1005 points
Part Number: TPS61291


Hi,

Please find the attached Boost Converter schematic design file. Kindly go through the design and let us know if anything to be modified for our requirement.

Here is the battery drain characteristics:

Device always in sleep - Sleep Current : <10uA

 Below mentioned pulse drain once in every configured interval (This interval can be configured from 10 Minutes to 1 Week)- default is 1 Week

 Active Current 1 : 3mA (For max 1 Sec)

Active Current 2 : 200mA (For max 2 Sec)

Active Current 3 : 1mA (For max 5 Sec)

Note: I need to know the selection of capacitor in the input side of battery as we need to transmit 200mA peak current for 2Sec duration of time [ This will happen once in every week] 

Thanks,

Rahul

  • 0
    TI__Mastermind 46905 points
    hi
    i don't find your attachment.

    for your question about the input capacitor, the 2Sec duration can be considered as DC current for the boost converter. so i would suggest 10uF as recommended in the datasheet.
  • 0 in reply to Jasper Li
    Expert 1005 points

    Hi,

    Yes, I missed to attach the design [Schematic file], PFA

    Actually my load will take 200mA  for  2Sec duration in weekly once. so the coin cell manufacturer suggested us to use a capacitor which can take care of the 200mA peak current for the 2Sec duration.

    My requirement is that how to select the suitable capacitor for the battery side.

    TI Based Boost Converter Design.pdf

  • 0 in reply to Rahul
    TI__Mastermind 46905 points
    1. in the schematic, the VSEL should be connected to GND, VOUT or floating

    we can calculate the input capacitor by the energy requirement during this 2Sec
    a. the total energy in the output is 0.2A*VOUT*2sec
    b. the energy from the input side is 0.2A*VOUT*2Sec/0.85, the value 0.85 is the conversion efficiency
    c. the energy from a capacitor is 0.5*C (Ua*Ua-Ub*Ub). the Ua is the input capacitor voltage before the 2Sec load; the Ub is the capacitor voltage after 2Sec (normally Ua=3V, Ub=1.5V)
    d. if the current from the battery is zero during this period, all the energy is supplied by the input capacitor. the capacitor can be calculated by setting 0.5*C (Ua*Ua-Ub*Ub) = 0.2A*VOUT*2Sec/0.85.
  • 0 in reply to Jasper Li
    Expert 1005 points
    Hi,
    Thanks a lot for your response. Let me find the values as per the formula.