SNVAA63 March   2023 TPSM365R6

 

  1.   Abstract
  2.   Trademarks
  3. 1Inverting Buck-Boost Topology
    1. 1.1 Concept
    2. 1.2 Output Current Calculations
    3. 1.3 VIN and VOUT Range in Inverting Configuration
  4. 2Design Considerations
    1. 2.1 Additional Bypass Capacitor and Schottky Diode
    2. 2.2 Start-up Behavior and Switching Node Consideration
  5. 3External Components
    1. 3.1 Capacitor Selection
    2. 3.2 System Loop Stability
  6. 4Typical Performance
  7. 5Digital Pin Configurations
    1. 5.1 Digital Input Pin
    2. 5.2 Power-Good Pin
  8. 6Conclusion
  9. 7References

1.1 Concept

In a standard buck configuration, the positive connection VOUT, is connected to the internal inductor, and the return connection is connected to the device ground.

In the IBB configuration, SYS_GND is connected to TPSM365R6's VOUT pin and the device return is now the negative output voltage, -VOUT. This shift in topology allows the output voltage to be inverted with respect to the input voltage. Pins connected to the TPSM365R6 IC GND in the standard buck configuration can still be referenced to the same pin in the inverting buck boost configuration. However, to use the EN and PGOOD pins, an appropriate level shifter must be added, which are detailed in the sections Section 5.1 and Section 5.2.

Figure 1-1 Converting From Buck to Inverting Buck-Boost Topology