SNOAA65 December   2020 TLV9022

 

  1.   Introduction
  2.   Design Process
    1.     Voltage Regulation
    2.     Undervoltage Protection With Hysteresis
    3.     Overcurrent Protection
    4.     Final Considerations
    5.     Simulation Results
  3.   Design References
  4.   Design Featured Comparator
  5.   Design Alternate Comparator

Overcurrent Protection

GUID-20201215-CA0I-QJ5K-CJCH-SKBVZXVL9WLK-low.svgCompleted Overcurrent Protection Circuit With Simulated Load Current

To determine an appropriate overcurrent value, it is recommended to set the limit to roughly half of the battery usage rating or use the maximum discharge current rating of the battery. For this design, we are assuming a usage rating of 20Ah. This means we selected an overcurrent threshold of 10A. This approximately translates to two hours of battery life if the maximum current rating is maintained. A 10-mΩ resistor is used to sense the load current. This means that when a voltage of approximately 100mV is seen by the first channel of the TLV9022, the combined output of the channels will be pulled low. Using the resistive network in the previous image, where R1 and R2 are equal to 200kΩ and 6.25kΩ, respectively, will step the VTL voltage down from 3.29-V to approximately 100mV. This establishes the overcurrent threshold at 10A.