LMR36506-Q1: Suggested CVCC and Drop-out mode during FPWM operation

Kazuki Kuramochi

Part Number: LMR36506-Q1

Hello Expert,

Our customer is considering to use LMR36506-Q1.
Then, we have questions for this device.

They are selecting external components for this device.
Regarding CVCC, I understand that suggested 1uF is including variation(temp, DC Bias, etc...)
However, we want to know about more detailed target of this point.
How large variation is it anticipated at CVCC?(e.g. -50%, etc...)

For the drop out operation, they plan to use this device with FPWM mode.
Then, will drop out operation appear in FPWM mode?
I guess it is related Vin/Vou and minimum off time so i guess it probably appear but I'd like to confirm it just in case.

Thank you and best regards,
Kazuki Kuramochi

over 1 year ago

0 Daniel Li14 over 1 year ago

TI__Mastermind 27040 points

You can follow EVM CVCC parameters which is 16V 1uF X7R +-10%

For FPWM, it will operate at dropout condition when Vin is close to Vo.

Thanks

0 Kazuki Kuramochi over 1 year ago in reply to Daniel Li14

TI__Genius 9180 points

Hi Daniel,

Thank you for your swift reply.

EVN's MLCC has slightly good performance(DC Bias, temp variation, etc...) rather than our customer selected MLCC even though whose specification is same as 16V 1uF X7R +-10%.
http://download.siliconexpert.com/pdfs/2015/3/14/11/33/43/336/tay_/manual/10552emk107b7105kaht_ss.pdf.pdf

I think this small difference don't have impact but this is for ASIL-B application so we want to make sure about this point.

Therefore, would you tell me the margin for capacity degradation on CVCC or could you tell me whether they can use their selected capacitor for CVCC?

Thank you and best regards,
Kazuki Kuramochi

+1 Daniel Li14 over 1 year ago in reply to Kazuki Kuramochi

TI__Mastermind 27040 points

yes, I agree that customer’s capacitor is OK for this application. But I don’t have the detailed data of CVCC degradation. As datasheet application section mentioned 1uF 16V is needed, and better than X5R should be ftiting for CVCC, slightly Bias or temperature different won’t impact the circuit .

thanks

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LMR36506-Q1: Suggested CVCC and Drop-out mode during FPWM operation