LM3630A: Why the inductance exists whistle ?

Hi Troyson,

    For your schematic, you have floated the "PWM" pin? How to achieve dimming? You need to connect the"PWM" pin to achieve the current dimming. ( Or connect the "PWM" pin to a high level)

    Are you toggling the "HW_EN" pin? 

    And since you just use one channel, have you disabled another channel?

BR

Sean

Hi Troyson,

    For your schematic, you have floated the "PWM" pin? How to achieve dimming? You need to connect the"PWM" pin to achieve the current dimming. ( Or connect the "PWM" pin to a high level)

    The dimming is controlled by I2C(Register_. Brightness A)

    Are you toggling the "HW_EN" pin? 

    Yes.Customer input high level to enable the device .

    And since you just use one channel, have you disabled another channel?

    They do not connect the another chanel ,The led2 is floating

     Besides, we have tesed some waveforms. Hope it's good for you . We can find the frequency in Picture.1 & Picture.1 is <20khz which may cause the sounds

     Picture.1 The waveform in D3 (Diode)-2 pin

   Picture.2 The waveform in  ILD1 pin

      Picture.3 The waveform in SW pin

     Picture.4  The waveform in SW pin

     Picture.5 The SCH

Hi Troyson,

    Picture 1-3 can't show now and you need to disable the channel two with the regs. reg0x00= 0x84; reg0x01=0x08.

    And have you read the reg0x0B? this is a fault register that may have some information.

BR

Sean

Hi Sean ，

        OK.  Customer just used LED1.But they enable the 2 led chanel . So If customer float the LED2 pin .The deveice will work abnormally?