TIDUCV2B April   2017  – January 2023

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Overview
    1. 1.1 System Description
    2. 1.2 Key System Specifications
    3. 1.3 Highlighted Products
      1. 1.3.1 TPS82130
    4. 1.4 Design Considerations
      1. 1.4.1 Inverting Buck-Boost Topology Concept
      2. 1.4.2 VIN and VOUT Range
      3. 1.4.3 Maximum Output Current
        1. 1.4.3.1 Thermal Limits
        2. 1.4.3.2 Stability Limits and Output Capacitor Selection
      4. 1.4.4 Design Precautions
      5. 1.4.5 Enable Pin Configuration
      6. 1.4.6 Power Good Pin Configuration
      7. 1.4.7 Discharging Output Voltage
      8. 1.4.8 Input Capacitor Selection
  7. 2Getting Started Hardware
  8. 3Testing and Results
    1. 3.1 Test Results
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 Layout Prints
    4. 4.4 Gerber Files
    5. 4.5 Assembly Drawings
  10. 5Related Documentation
  11. 6Trademarks
  12. 7Revision History

1.4.2 VIN and VOUT Range

The input voltage that can be applied to an integrated circuit (IC) operating in the inverting buck-boost topology is less than the input voltage for the same IC operating in the buck topology. The reason for this difference 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 TPS82130 is 3 V to 17 V + 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 must be set between –0.9 V and –6 V. The output voltage is set in the same way as the buck configuration, with two resistors connected to the FB pin. Use the same equation in the TPS82130 datasheet to set the output voltage, keeping both VOUT and VFB as positive values. The TIDA-01405 design sets the output voltage at –1.8 V, which gives an input voltage range of 3 V to 15.2 V.