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TPS61010: TPS61010 buzzing from coil issue

Shai Berman
Mastermind 7400 points
Part Number: TPS61010

Hi,

I have a question on my behalf of my customer (application: Flashlight): 

Please find below the customer's questions:

  1. What is the correct value for the feedback resistors of the TPS61010 ?
  2. When working with 4 green LED's in parallel (Vout = 2.95V, feedback is 180K, 949K) with no current limit resistor, I have a current of ~17mA. When the battery is fresh I hear a clear buzzing from the coil which disappears after a few minutes of continues work and doesn't return. Please advise how to solve this issue.

Please can you advise back, I will really appreciate it. 

Thanks in advance

Regards.

Shai Berman

  • 0
    TI__Mastermind 46905 points
    1. the low side feedback resistor should be lower than 500Kohm, then the high side feedback resistor can be calculated based on the reference voltage and output voltage. the 180K+949K is in your application is acceptable.
    2. we may hear the noise when the switching frequency locates in acoustic noise frequency range. you can measure the frequency in SW pin to check the difference of a fresh battery and non-fresh battery. you can try to replace the coil with better one if you confirm that the noise is caused by the coil, not the ceramic capacitor.
  • 0 in reply to Jasper Li
    Prodigy 20 points

    Thanks Jasper

    I will follow your advise

    Best,

    Udi