SLVA478C October   2013  – November 2022 TPS62120 , TPS62122

 

  1.   Using the TPS62120 in an Inverting Buck-Boost Topology
  2.   Trademarks
  3. 1Inverting Buck-Boost Topology
    1. 1.1 Design Considerations
    2. 1.2 Concept
    3. 1.3 Output Current Calculations
    4. 1.4 VIN and VOUT Range
  4. 2Digital Pin Configurations
    1. 2.1 Enable Pin
    2. 2.2 SGND Pin
    3. 2.3 Power Good Pin
  5. 3Startup Behavior and Switching Node Consideration
  6. 4External Component Selection
    1. 4.1 Inductor Selection
    2. 4.2 Input Capacitor Selection
    3. 4.3 Selecting L and COUT for Stability
  7. 5Typical Performance and Waveforms
  8. 6Conclusion
  9. 7References
  10. 8Revision History

4.1 Inductor Selection

When selecting the inductor value for the inverting buck boost topology, the equations provided in Output Current Calculations should be used instead of the ones provided in the data sheet. (IL(max) should be kept below the minimum current limit value of the device (0.2 A) for a reliable design.) It is recommended to size the inductor for the current limit level of the TPS62120, as this level is sometimes reached during startup (shown in Figure 3-1). See Section 4.3 for the stability impact of the inductor selection.