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LMR43620-Q1: 200mV output ripple voltage on NO LOAD condition

DINESH SELVARAJ
Prodigy 10 points
Part Number: LMR43620-Q1
Other Parts Discussed in Thread: LMR43620MQ3EVM-2M

I am getting 200mV output ripple voltage on NO LOAD condition and below list of components changed on TI Eval kit (LMR43620MQ3EVM-2M) to meet our output voltage requirements.

RFBT

88.7k

RFBB

11.3k

L1

2.2uH

VinMin = 9.0V

VinMax = 16.0V

Vout = 8.75V

Iout = 0.1A

Note:

Inductor part number: HCM1A0703-2R2-R

Inductor spec: 2.2uH / 20 mOhms / DC current 5.7A / K-factor 309

MODE/SYNC pin connected to ground.

Could you please help me to reduce the output ripple voltage on NO LOAD condition?

  • 0
    TI__Mastermind 22200 points

    Hi Dinesh,

    You can try to increase output capacitance by populating C13. You may also use Webench to find a starting value and then adjust from there. The datasheet advises to not go above 10x the design value, or 1000uF, whichever is small. Please make sure to also check load transient conditions to make sure that your performance is satisfactory. 

    Regards,

    Richard

  • 0 in reply to Richard Fu22
    Prodigy 120 points

    Hi Richard thanks for your reply.

    Could not find any improvement by adding capacitor. Is there any other option to try?

    Regards,

    Sudharshana

  • 0 in reply to sudharshana panduranga
    TI__Mastermind 22200 points

    Hi Sudharshana,

    Apologies for the delay in response. Another possibility is to have the part operate in FPWM mode at light load instead of AUTO mode. AUTO mode may reduce your switching frequency, which can result in increased output ripple with a benefit to increased efficiency. I'll also assign this thread to the engineer in charge of E2E this month. 

    Regards,

    Richard