• TI Thinks Resolved

TIPD138: About the cutoff frequency

Part Number: TIPD138

In the design of low pass filter value is 1.5 MHz, I want to ask why is 1.5 MHz rather than other values, the value is calculated according to what condition.

  • Hello,

    I did not personally design TIPD138, but, it appears to me that the selection of 1.5MHz was a relatively arbitrarily selected frequency for the cutoff of this filter. As far as performance of the components used in the design there is no particular component that is contributing a different noise profile above 1.5MHz, I would say they're just reducing the broadband noise. The only guiding factor perhaps considered is that most analog components PSRR starts to fall off pretty dramatically above 100kHz so maybe they wanted to reduce this noise.

    Kevin Duke
    Systems Engineer