LM5022-Q1: LM5022: does it support DCM mode?

Steffen Mauch1

Prodigy 30 points

Part Number: LM5022-Q1
Other Parts Discussed in Thread: LM5022

Hello,

I haven't found reliable information whether the LM5022 can be used in DCM mode.

I do not have a load at all time, thus, the buck converter will need to support DCM mode.

Thank you

over 5 years ago

0 Richard Fu22 over 5 years ago

TI__Mastermind 31075 points

Hi Steffen,

Do you mean boost operation instead of buck?

Discontinuous Conduction Mode (DCM) operation is inherent in any SMPS topology. This will occur when the inductor current ripple is larger than half the average inductor current. In this case, you will need to make sure your power-train and compensation component selection can handle both CCM and DCM cases.

Please see this paper for a more detailed analysis:

https://www.ti.com/download/trng/docs/seminar/Topic_3_Lynch.pdf

Thanks,

Richard

0 Steffen Mauch1 over 5 years ago in reply to Richard Fu22

Prodigy 30 points

Hi Richard,

yes sorry for the typo, I meant boost.
Do I have to understand your answers as yes, no load condition is no problem for the LM5022?
I know that at least some ICs require a minimum load to circumvent DCM.
The LM5022 datasheet only mentioning CCM; thus I am a little worried.

Thanks

0 Richard Fu22 over 5 years ago in reply to Steffen Mauch1

TI__Mastermind 31075 points

Hi Steffen,

Sorry for unclarity.

You are correct, no load condition is no problem for the LM5022. You will simply need to adjust your power-stage and compensation to make sure all cases are covered.

Thanks,

Richard

0 Steffen Mauch1 over 5 years ago in reply to Richard Fu22

Prodigy 30 points

Thank you Richard.
Just one note:
Equation 3 in section 8.2.2.2 of the LM5022 datasheet is wrong.

There is a power of two missing as right now only I*R is written.
Later on, equation 62 is correct.

Thanks
Steffen

0 Richard Fu22 over 5 years ago in reply to Steffen Mauch1

TI__Mastermind 31075 points

Hi Steffen,

Thanks for the heads up. I will work with the team to see if we can update this datasheet.

Richard

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LM5022-Q1: LM5022: does it support DCM mode?