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TPS62480: TPS62480 variable Vout operation

Alex Missler
Prodigy 40 points
Part Number: TPS62480
Other Parts Discussed in Thread: TPS62870-Q1, TPS62869, TPS62867, TPSM82866A

Hi,

I'd like to use a TPS62480 for supplying a load with a variable voltage via a DAC.

1) I understand that this type of operation is outside the intended scope of this package but if it's possible, I would like to know if there is a way to control Vout using a DAC.

2) If so, is it controlled by a current of a voltage, with which pin ?

3) Can the current simulations models for the TP62480 for Pspice for TI simulate this behavior ?

Here is my current design:

 Vin is delivered with a 3.7V battery, VDD is at 3.3V, and the load is 0.6V.

I would like the TPS62480 to deliver below 9W power to the load.

Thanks

  • 0
    TI__Guru*** 148130 points

    Hi Alex,

    Yes, this is possible with many DC/DCs.  Here is my app note on the topic, which you can find on the above product folder: https://www.ti.com/lit/an/slyt777/slyt777.pdf 

    We also have the TPS62869 and TPS62870-Q1, which adjust the voltage via I2C if that is easier.

    Finally, the TPS62867 is a newer and smaller device and would be my recommendation instead of the TPS62480.

    Thanks,

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 40 points

    Hi Chris,

    I assume Vfb in the (1) formula is fixed at 0.6V, is it correct ?

    If my load is purely resistive, won't my control voltage I apply with the DAC also depend on the load's current value ?

    I wish TPS62869 and TPS62870-Q1 were available but they seem out of stock, I must make do with TPS62480 for this design.

    Thanks,

    Alex

  • 0 in reply to Alex Missler
    TI__Guru*** 148130 points

    Yes, 0.6V in that equation.

    No, the DAC voltage is independent of the load current.  This is the same as for normal Vout regulation--the IC regulates the output voltage with a varying load current.

    TPS62869 and TPS62870-Q1 use I2C to adjust the output voltage.  You could use this same DAC circuit on the TPS62867 and/or TPSM82866A.

    I can't see what stock quantities you can see, but I think we should have some of the TPS62867 and/or TPSM82866A on ti.com.  How many do you need?

    Chris