SLVAG21 April   2026 TPS61381-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2System Overview
    1.     6
    2. 2.1 Design Considerations
    3. 2.2 System Design Theory
      1. 2.2.1 Supercapacitor Charging Operation
        1. 2.2.1.1 Calculation for Backup Supercapacitor Selection
          1. 2.2.1.1.1 Design Calculations
  6. 3Test Results
    1. 3.1 Standby Operation
    2. 3.2 Charging Operation
    3. 3.3 Boost Operation
  7. 4Summary
  8. 5References

2.2 System Design Theory

Figure 2-2 denotes a simplified block diagram which shows the various modes of operation. The working of the system can be categorized into three modes: standby, charging and boost operation mode. When the main supply is available to the system, the main supply is directly routed to the output with Vin = Vout. During the charging phase, the backup battery depending on the battery type is charged through LDO operation leveraging the input supply. In this case, use the supercapacitor for the backup power and the LDO performs the charging.

Block Diagram for System Operation Figure 2-2 Block Diagram for System Operation

Now, when the main input supply fails, and Vin goes below a certain designated threshold value, the device enters the boost mode and draws energy from the backup battery to regulate the output voltage. The boost operation can be operated at 400kHz.

The battery type and count, the charging topology, charging current, operation frequency and boost threshold can be configured through the I2C interface.