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TPS62812-Q1: PWM Switching frequency (variability)

Part Number: TPS62812-Q1

Hello Team,

I got a question about frequency variability.

When COMP/FSET connected VIN or GND directly, the Fsw variability is +/-10%.
When using using a resistor, the Fsw variability is 18%!


Why does the variability get wide just adding resistor?
In other words, if the resistoer has no variability, the frequency variability still keep +/-10%?

++++++++
Regards,
Toshihisa Ishii in TIJ/west Auto

  • Hi Toshihisa-san,

    The device tied with GND/Vin and Switching frequency will set to the predefined value and while device COMP pin connected to the resistor than the parasitics of trace, tolerance of resistor all will be added and these factors make the variability higher. The min/max value is suggested in the datasheets are measured for worse case conditions

    Best regards,

    Tanvee 

  • All right, thanks!
    Now I realized what a poor accuracy this device is.