SLUAAR8 December   2023 TPS56837

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Review of CCM Output Voltage Ripple in Buck Converter
  5. 2Calculation of DCM Output Voltage Ripple in D-CAP Buck Converter
  6. 3Bench Test Results and Error Analysis
    1. 3.1 Bench Test Results
    2. 3.2 Error Analysis
      1. 3.2.1 Variation in High-Side FET on Time
      2. 3.2.2 Variation in Component Value
  7. 4Comparison Between DCM and CCM Output Voltage Ripple in D-CAP Buck Converter
  8. 5Summary
  9. 6References

3.2.2 Variation in Component Value

There would be other factors needed to consider in application. Since used components are not ideal components, there would exist deviation in their mass production

Used COUT in bench test is default capacitor assembled on EVM, whose part number is GRM32ER71E226KE15L. Based on its specification, its typical value has ±10% variation in mass production. Capacitance has ±15% change rate when only working temperature changes.

Aside from output capacitors, the inductance value also has variation due to non-ideal characteristic. Used inductor is also EVM default one, whose part number is 744325330. The inductor has ±20% variation on its inductance, which could lead to different peak value of inductor current and output voltage ripple.

All of previous mentioned variation can result in mismatch of calculated output voltage ripple and tested output voltage ripple.