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BQ25620: EMI fail

cayden liu
Intellectual 1276 points
Part Number: BQ25620

Tool/software:

Hi TI,

I use BQ25620 develop project now. But find can`t pass the EMI.

Iout: 1A, 2A

Frequency: 60KHz, 108KHz

Looking forward you reply.

BR

Cayden

  • 0
    TI__Mastermind 31150 points

    Hi Cayden, 

    Please see my comments below regarding suggested EMI suppression techniques for BQ25620. 

    1)Add a 1 nF capacitor at PMID, SYS, VBUS (optional), and BAT (optional). The purpose is to add this high frequency cap which works in 100MHz to 200MHz range to return high frequency noise to GND. 

    2)Add snubber circuit (resistor and capacitor) from SW pin to GND. Use R = 1ohm and C = 15 nF as reference, but TI recommends to try several different combinations to get best results with your custom PCB design. 

    3)Add resistor (in range of 0 ohm to 5 ohm) in series with BTST capacitor from BTST pin to SW pin. The purpose is to reduce the switching slew rate. We do not recommend using higher resistors values than 5 ohm as it will start to adversely affect converter efficiency.

    Best Regards,

    Garrett