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TPS61196: Overcurrent limit protection

Danilo A.
Mastermind 28740 points
Part Number: TPS61196

Hi Team,

Our customer would like to know value of current to be used in finding R7. According to our customer,

We have used TPS61196 IC in our project. The problem is that we use 250mA current for each channel. So, the total current for 6 channels is 250mA x 6 channels = 1.5A. For finding the value of R7 in the datasheet in equation 7 which value will be used for Current 250mA or 1.5A?

Regards,

Danilo

  • 0
    TI__Mastermind 34810 points

    Hi Danilo,

    What's customer input voltage (Vin) and output voltage (Vout)?

    Simply you can calculate as below:

          IL = (Vout*Iout) / (Vin*efficiency)

          ILp = [Vin*(Vout-Vin)] / (L*Fsw*Vout)

          IL_peak = IL + ILp/2

    And IL_peak can be used to determine the current sense resistance (R7):

          R7_max = VISNS / IL_peak,    VISNS = 400mV Typ.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    TI__Mastermind 28740 points

    Hi Patrick, 

    Thank you for your response.

    I will ask for the VIn and Vout from our customer. Since he will drive 6 channels at 250mA, he will have to substitute 1.5A for Iout? Can you please confirm if his understanding is correct?

    Regards,

    Danilo

  • +1 in reply to Danilo A.
    TI__Mastermind 34810 points

    Hi Danilo,

    Yes, 6 channels at 250mA will get total Iout to 1.5A.

    But TPS61196 is only recommended for 200mA per channel continuous output current. 250mA per channel might need to use the pulse output for each channel.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    TI__Mastermind 28740 points

    Hi Patrick,

    Thank you for this information. Please see the feedback of our customer below.

    We need a total of 500 mA current per LED string and we have 3 such LED strings. Can we parallel two channels to get a total output current of 500 mA. I don't understand the concept of pulse output, can you please explain.

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Mastermind 34810 points

    Hi Danilo,

    You can understand like this: TPS61196 can only continuously output total 6*200mA=1200mA.

    So with 6*250mA, that means maybe LED string 1 and 2 are outputting 500mA continuously, but string 3 can't. If string 3 is continuously outputting 500mA, then string 1 or 2 can't. Their output current waveform are just like the "pulse".

    BR

    Patrick