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TPS62810-Q1: TPS62810-Q1 100%duty

Masayuki Uchihara
Intellectual 1655 points
Part Number: TPS62810-Q1

Hi team,

I have question about the 100% duty. If the input voltage is 5V and we want to ouput around 5V @ 1.5A, is there feasibility? I guess, it should be in the 100% duty mode and the output voltage should be 4.91V (Ron(60mohm)-Iout(1.5A)=Vdrop(0.09). Is it correct? we cannot see the minimum off time at 5V. could you tell us it? In addition to this, what the required input voltage not to in the 100% duty mode?

Best Regards,

Uchihara

 

  • 0
    TI__Mastermind 29516 points

    Hello Uchihara-san,

    Thanks for reaching out to us.

    If the input supply and output voltage are set at 5V, the VOUT will be definitely lower than 5V even at 100% mode due to voltage drop on the high-side FET and inductor (see formula below). When the input voltage is decreasing near Vout and reached the min toff of 30ns (typical), the IC stop the switching cycles and enters 100% mode.

    Vout (@ 100% mode) = VIN - (Rdson_HS-FET + DCR) * Iout 

    To ensure that the device does not go into 100% mode, the supply voltage should consider the worst case voltage drop across high-side FET and inductor (refer to formula below).

    VIN_min > Vout + (Rdson_HS-FET_max + DCR_max) * Iout_max

    where: 

       - VIN_min: lowest input voltage to ensure IC does not enter 100% mode

       - Rdson_HS-FET_max: 60-mohm

       - DCR_max: maximum DCR of the inductor

       - Iout_max: maximum output current

    Best regards,

    Excel

  • 0 in reply to Excel Regidor
    TI__Mastermind 29516 points

    Hello Uchihara-san,

    Just a gentle reminder. Do you still have additional queries? If not, can you kindly close the thread?

    Thank you.

    Best regards,

    Excel

  • 0 in reply to Excel Regidor
    TI__Mastermind 29516 points

    Hello Uchihara-san,

    I'm closing this thread. If you have additional queries, you can re-open it by adding comment.

    Thank you.

    Best regards,

    Excel