TPS62901: Fsw when Auto PFM/PWM and Iout is less than ILpp/2

Kazuhiko Hirano

Part Number: TPS62901

Hello,

My customer is using TPS62901 with 11kohms at MODE/S-CONF pin, external FB, Fsw=1MHz, OUTPUT DISCHARGE=yes and Auto PFM/PWM.
They are asking if there are any equations to calculate Fsw when Iout is smaller than half of the ripple current of the inductor.
Could you let them know the equation if it is available, please?

Best regards,

K.Hirano

over 4 years ago

0 Jose Couso over 4 years ago

TI__Mastermind 27321 points

Hello Hirano,

Unfortunately, there's no way for us to calculate the FSW. For best FSW estimation, they can use "WEBENCH^® Designer for TPS62901".

Here's the link for the WEBENCH:

https://webench.ti.com/power-designer/switching-regulator/customize/13?VinMin=3.5&VinMax=17&O1V=3.3&O1I=1&base_pn=TPS62901&AppType=None&Flavor=None&op_TA=30&origin=pf_panel&lang_chosen=en-US&optfactor=3&Topology=Buck&flavor=None&VoltageOption=None

Best,
Jose

+1 Joseph Conrad over 4 years ago

TI__Expert 7860 points

Hi Hirano,

When Iout drops below half the ripple current in the inductor, it enters DCM (Discontinuous Mode) operation and the Fsw can be estimated using the following equation:

Thanks,

Joseph

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TPS62901: Fsw when Auto PFM/PWM and Iout is less than ILpp/2