SNVAA71 October   2023 TPSM63610

 

  1.   1
  2.   Using the TPSM63610/08 for Negative Output, Inverting Buck Boost Application
  3.   Trademarks
  4. 1Inverting Buck-Boost Topology
    1. 1.1 Concept
    2. 1.2 VIN and VOUT Range In Inverting Configuration
    3. 1.3 Output Current Calculations
  5. 2Design Considerations
    1. 2.1 Additional Bypass Capacitor and Schottky Diode
    2. 2.2 Start-up Behavior and Switching Node Consideration
  6. 3External Components
    1. 3.1 Capacitor Selection
    2. 3.2 System Loop Stability
    3. 3.3 UVLO
  7. 4Typical Performance
  8. 5Digital Pin Configurations
    1. 5.1 Digital Input Pin (EN)
    2. 5.2 Power-Good Pin
  9. 6Summary
  10. 7References

5.2 Power-Good Pin

The TPSM63610 has a built-in power-good (PGOOD) function to indicate whether the output voltage has reached its appropriate level or not. The PGOOD pin is an open-drain output that requires a pullup resistor. Because the negative VOUT is the IC return in this configuration, the PGOOD pin is referenced to negative VOUT instead of ground, which will not provide the appropriate system voltage levels which need to be referenced to ground. This means that the device pulls PGOOD to VOUT when it is low.

This can cause difficulties in reading the state of the PGOOD pin, because in some applications the IC detecting the polarity of the PGOOD pin may not be able to withstand negative voltages. The level shifter circuit (as shown in Figure 5-2) ensure the correct system voltage signal referenced to ground. The VCC voltage must be at an appropriate logic level for the circuitry connected to the "SYS PG" net.

GUID-18753669-BE6C-45E8-B0C6-56498A9D19F9-low.svgFigure 5-2 PGOOD Pin Level Shifter