SLVAFU9 January   2025 TPS62840 , TPS62843

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Inverting Buck-Boost Topology
    1. 1.1 Concept
    2. 1.2 Output Current Calculations
    3. 1.3 VIN and VOUT Range
  5. 2Design Considerations
    1. 2.1 Additional Input Capacitor
    2. 2.2 Digital Input Pin Configurations
    3. 2.3 Startup Behavior and Switching Node Consideration
  6. 3External Component Selection
    1. 3.1 Inductor Selection
    2. 3.2 Capacitor Selection
  7. 4Typical Performance
  8. 5Summary
  9. 6References

1.3 VIN and VOUT Range

The input voltage that can be applied to an inverting buck-boost converter IC is less than the input voltage that can be applied to the same buck converter IC. This is because the ground pin of the IC is connected to the (negative) output voltage. Therefore, the input voltage across the device is VIN to VOUT, not VIN to ground. Thus, the input voltage range of the TPS6284x is 1.8V to 6.5V + VOUT, where VOUT is a negative value. The output voltage range is the same as when configured as a buck converter, but negative. The output voltage for the inverting buck-boost topology can be set the same way as in the buck configuration, with the RSET resistor connected to the device GND pin.