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BQ24250: Waht is the function of Vdmp treshold?

carlosgdj07
Prodigy 240 points
Part Number: BQ24250

Hello everybody,

I am currently working with BQ24250RGET IC and I don't know how to configure R1 and R2 to establish Vdpm value. What is the purpose of this Vdpm voltage treshold?

I am going to provide BQ24250RGET with 5V from a DC/DC converter which I have configured to limit the current provided to 1,5Amps. So as long as I already have a limitation in the current I am supplying to BQ24250RGET, I dont want BQ24250RGET to provide any other protection at Vin (pin 19)...

Thank you very much!

Best regards.

  • 0
    TI__Guru**** 165886 points

    Hi Carlos,

    The VDPM (or VINDPM) feature is used as a second line of defense against the charger crashing its power source.  If the system load + charge current are too large for the power source or the cable from the power source to the IN pin is highly resistive,  the charger's VINDPM feature regulates its input voltage to the VDPM threshold, effectively reducing input current limit further, to prevent input power source crash.  With input power limited, the charger first reduces charge current and then system output current, potentially causing V(SYS) to droop. 

    If you do not want to use the VDPM feature, you can short the VDPM pin to  a default of 4.68V for the input DPM threshold.  I recommend that you connect the resistors as a fail safe, setting the VDPM level to 4.5V, which is the minimum USB voltage level but you could set it even lower in order to effectively disable the feature.

      

  • 0 in reply to Jeff F
    Prodigy 240 points
    Dear Jeff,

    Thanks a lot for your explanation. Now I am able to design properly.

    Best regards,