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TPS62871: Output regulate working model

Roy Hsu
Intellectual 2880 points
Part Number: TPS62871
Other Parts Discussed in Thread: TPS54620

Hi Expert,

I would like to know if I use I2C set TPS62871 VREF as 0.5V, VOSNS and GOSNS connect to remote sense output voltage and GND accordingly, no matter VOSNS pin voltage higher or lower than 0.5V then the TPS62871 will regulate VOSNS voltage to 0.5V by PWM correct?

Actually I would like to know is if TPS62871 VOSNS pin voltage higher or lower than VREF then Duty will lower or higher to make VOSNS voltage keep same as VREF, because in TPS62871 block diagram it’s a little bit different compared with normal POL, normal POL it will be a error amp and + side will be VREF but TPS62871 not.

Thanks.

Best Regards,

Roy

  • 0
    TI__Guru**** 150950 points

    Hi Roy,

    The voltage source between GOSNS and the gm is what is adjusted with the I2C.  It is meant to indicate that the device regulates the differential output voltage to the set Vout.

    The + side of the error amplifier is always connected to the Vref, while the - side (the inverting input) is connected to Vout in order to give negative feedback.  Here is how the TPS54620 shows it, for example:

    Also, see this app note for a deeper explanation of the topology: https://www.ti.com/lit/an/slyt846/slyt846.pdf

    Thanks,

    Chris