SPVA032 September   2025 LM5152-Q1 , LP8866-Q1 , LP8866S-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Expected System Challenges Without Pre-Boost
    1. 2.1 Undervoltage Protection of High-Side Switch
    2. 2.2 System Bias Power Interruption
    3. 2.3 Unexpected Lower Input Voltage on LED Driver
    4. 2.4 Unexpected Higher Input Current Condition in the System
  6. 3Design Suggestion to Resolve the System Challenges by Using Pre-Boost
    1. 3.1 Block Diagram and Test Results
    2. 3.2 Key Design Considerations
  7. 4Summary
  8. 5References

Abstract

This application note introduces pre-boost designs for automotive display applications which can make the system more robust. Depending on the original equipment manufacturer (OEM) requirement of the vehicle, normal operation should be verified under low battery voltage condition such as 6V due to cranking and auto-start conditions using a typical 12V car battery. Take care to achieve normal operation under low voltage condition in real designs, considering system level challenges. Designers can make the system more robust by using pre-boost. LM5152-Q1 is a synchronous boost controller which can function as pre-boost controller if the battery voltage is low. This application note uses a design example using LP8866(S)-Q1 which is TI's automotive global dimming LED driver according to display market trends.