SLVAEN1A February   2020  – November 2022 TPS61022 , TPS61023

 

  1.   Adjustable Undervoltage Lockout Circuit Used in TPS61022 and TPS61023
  2.   Trademarks
  3. 1Introduction
  4. 2Proposed Circuit Principle
  5. 3Bench Test
  6. 4References
  7. 5Revision History

1 Introduction

Table 1-1 is a portion of the electric specification from the TPS61022 and TPS61023 data sheet. The undervoltage lockout (UVLO) threshold is 1.7 V at the rising edge and 0.4 V at the falling edge. This means if the EN pin is logic high:

  • The device starts up when the VIN pin is higher than 1.7 V.
  • After the output voltage (VOUT) rises higher than 2.2 V, the device only shuts down again after the input voltage becomes lower than 0.4 V.

Table 1-1 TPS61022 and TPS61023 VIN pin UVLO Specification
ParameterTest ConditionTYPICALMAXUnit
VIN_UVLOUndervoltage lockout thresholdVIN rising1.71.8V
VIN falling0.40.5V

This ultra-low UVLO feature is useful in applications such as a super-capacitor power system. It helps to utilize all the energy from the super capacitor. However, the feature is not always desired. If the converters are powered with two alkaline batteries in series, of which the operation voltage is between 3.2 V to 1.4 V, the minimum operating voltage is unnecessary to below 1.2 V. Shutting down the boost converter at a higher voltage can help to select the external components easily, such as an inductor and capacitor, and it also helps to protect the battery from being overly discharged.

This application report introduces a circuit to shut down the TPS61022 and TPS61022 devices at a voltage higher than 0.4 V. Using the TPS61022 device as example, theoretical analysis and bench test result are presented to verify the proposed circuit.