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DRV2603EVM-CT: None zero output with zero PWM input when it was on External PWM mode (for LRA Auto Resonance On)

Part Number: DRV2603EVM-CT
Other Parts Discussed in Thread: DRV2603

I am trying to drive external LRA by using the external PWM mode of DRV2603 evaluation kit. Even I didn't connect any input, the output line shows pk-pk 2.24V output like the picture below.

I put the board into the Additional Hardware Modes and selected Mode3 B2

Also I realized when I use Mode3 B3(enable with LRA auto-resonance off) the noise goes away but the LRA gets hot really quickly.

Thank you for helps

 

  • Hi Jung Hwa Bae,

    A colleague will be responding soon with further information.

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer
  • Hi Jung,

    Thanks for posting! The DRV2603 EVM has two outputs that should be measured independently. Then you can use the MATH function on your oscilloscope to find the differential output.
    When you have nothing connected, both outputs are in phase producing ~2.2Vp output. Differentially, the output is 0V.
    I'm looking into the functionality of button B3. The resonance tracking cannot be disabled, so I'm a little unsure about this mode. It appears to just be outputting a DC voltage on one output.

    Use a PWM input above 50% duty cycle and the device should track the frequency and work correctly. Let us know if you have trouble getting this to work.