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LMR23610: Input Amperage Rating

Diego Chavez
Prodigy 40 points
Part Number: LMR23610
Other Parts Discussed in Thread: TPSM84205

Hello, my name is Diego, I am a 16 year old maker from Guatemala, and I really need some help. I am trying to find a way to step down the voltage and current from my 12v 60A lithium ion battery pack that I built to 5V 1A. I found the LMR23610 but it doesn't say what the input current is on any of the paperwork, can somebody help me please? 

  • 0
    TI__Guru**** 191445 points
    Hi Diego,

    You can estimate that from the front page of the datasheet. There is a graph of efficiency that has your exact conditions of 12 V input and 5 V output. The efficiency is approximately 94 % at 1 A output. Iin = ( Vout * Iout) / (Eff * Vin) = ( 5 * 1 ) / (0.94 * 12) = 0.443 A.
  • 0 in reply to JohnTucker
    Prodigy 40 points
    Thank you, I did see that but I am still wondering if it will take the 60 amps from my battery without burning out, is there anywhere I can see what it's current rating is?
  • 0 in reply to Diego Chavez
    TI__Guru**** 191445 points
    For a buck converter, the input current is directly related to the output current. It should only draw what it needs from your battery.
  • 0 in reply to JohnTucker
    Prodigy 40 points
    Great! thank you very much, I am really sorry to keep bothering you with my beginner questions but do you know of a way in which I could step down the current from 60 to 1 amp?
  • 0 in reply to Diego Chavez
    TI__Guru**** 191445 points
    Diego,
    LMR23610 cannot draw 60 A from the input. Buck converters step down voltage, not current. The efficiency of that conversion,
    n = (Vout * Iout) / (Vin * Iin). Since you know your output voltage is 5 V , your output current is 1 A and your input voltage is 12 V, you can calculate the input current based on the efficiency as shown in the front page graph. The output current ( and hence the input current for a given input and output voltage) is limited by the internal current limit as specified on page 5 of the datasheet.
  • 0 in reply to Diego Chavez
    TI__Mastermind 25590 points

    Hey Diego,

    Thanks for stopping by E2E!

    I wanted to recommend our TPSM84205 module. This is a module that is pretty much fully assembled. It has 3 pins, VIN, VOUT, Ground.

    • You give VIN a voltage between 7V and 28V.
    • It will automatically set VOUT = 5V.
    • You can draw up to 1.5A OUT (so your 1A out is fine)

    So at your specs, 12VIN, 5VOUT, 1AOUT, the part will automatically pull about 0.5A from your battery.

    The schematic is below. We recommend putting some capacitors on VIN and VOUT to smooth the voltage, but the rest is on the TPSM84205 board already.

    Hopefully this helps. Have fun!

    -Sam