SDAA032 July   2025 TDA4VE-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Understanding PWM Operation on TDA4x
    1. 2.1 PWM Architecture Overview
    2. 2.2 Counter-Compare Register and Duty Cycle Control
    3. 2.3 Action Qualifier and Output Behavior
    4. 2.4 Synchronization and Update Timing
  6. 3Unintended PWM Duty Cycle from Immediate CMPA Update
  7. 4Unintended PWM Duty Cycle from Up-Down Count Mode
  8. 5Best Practice for Seamless PWM Updates for LED Dimming Control
    1. 5.1 Use Shadow Registers for Duty Cycle Updates
    2. 5.2 Select the Appropriate Counter Mode
    3. 5.3 Register Configurations for Up-count Mode Under Shadowing
  9. 6Summary
  10. 7References

Abstract

Pulse Width Modulation (PWM) is a core technology used across many embedded applications including LED dimming control, motor control, and power regulation. When PWM duty cycle updates are made without proper synchronization, the PWM can introduce unintended PWM duty cycle causing unintended behaviors of corresponding devices such as unintended LED flicker or motor torque control. These effects are undesirable in both visual and functional applications, particularly where precision and smooth operation are required. This application note explains how undesirable duty cycle can occur and how to overcome this problem for seamless PWM duty cycle transitions using the Enhanced Pulse Width Modulation (EPWM) module on the Texas Instruments TDA4x platform by presenting LED dimming control example.