SLVAFJ1 February   2023 TPS2121


  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Design Example Specification
  4. 2Design Considerations
    1. 2.1 Highest Voltage Operation Scheme (VCOMP)
    2. 2.2 Output Voltage Dip and Switchover
    3. 2.3 Overvoltage Calculation
  5. 3Test Results
    1. 3.1 Seamless Switchover from Main Power (IN1) to Backup Power (IN2)
    2. 3.2 Seamless Switchover from Backup Power (IN2) to Main Power (IN1)
  6. 4Summary
  7. 5References


This application note introduces automatic switchover design not using GPIO(General Purpose Input Output) signal from MCU (Micro Controller Unit) for increasing battery run time. This is a requirement for applications using solar cell or variable source as main power and battery as backup power. The battery must be used as the power source of the system if main power source gets lower than target voltage to maintain minimum Vout. MCU can be used to monitor the power inputs and select the power source with GPIO between battery and main power source. However, this means MCU must be in active mode even using battery as a power source. This is very critical for the applications which require long battery run time. This report shows how to implement automatic switchover using TPS2121 for longer battery run time with MCU in sleep mode from required application.