REF50: Output capacitor ESR for low current consumption

Clément Letonnelier

Part Number: REF50
Other Parts Discussed in Thread: TPS7B4253-Q1,

Tool/software:

Hi,

The datasheet of the REF50 recommends a 1Ω to 1.5Ω ESR capacitor on its output to avoid output oscillation.

I believe this is recommended in design where there is current demand (e.g. when used to drive an analog to digital converter).

We have an existing design where we don't meet that requirement and have no issue, so I am trying to check if there is no hidden issue ?

We are using the REF5010 to drive the ADJ input of the TPS7B4253-Q1 which I believe does not need so much current.

Best regards,

Clément

5 months ago

+1 Jackson Wightman 5 months ago

TI__Expert 8730 points

Hi Clément,

Just to make sure there is no confusion, here is what the datasheet says:

So, as long as the load capacitor's ESR is less than or equal to 1.5Ω, there shouldn't be any concern about stability. Most ceramic capacitors should meet this with no issue. If you have an ESR that is above 1.5Ω, there is risk of instability, regardless of the current demand.

Thanks,

Jackson

0 Clément Letonnelier 5 months ago in reply to Jackson Wightman

Expert 2796 points

Hi Jackson,

Indeed, I focused on the next sentenced which indeed said "recommended".

Thank you,

Clément

0 Jackson Wightman 5 months ago in reply to Clément Letonnelier

TI__Expert 8730 points

Hi Clément,

Glad I could be of help.

In the future if you would like improved noise performance without worrying as much about specific ESR values, we have released a new enhanced version with voltages that range from 2.5V to 5V: REF50E. It has 0.5 ppm p-p noise. More information can be found here:

https://www.ti.com/product/REF50E

Thanks,

Jackson

0 Clément Letonnelier 5 months ago in reply to Jackson Wightman

Expert 2796 points

Jackson,

Yeah I saw it but the 10V version is not part of that enhancement from what I understood.

Clément

0 Jackson Wightman 5 months ago in reply to Clément Letonnelier

TI__Expert 8730 points

Hi Clément,

That is correct. Let me know if there are any other questions.

Thanks,

Jackson

Power management

Power management forum

REF50: Output capacitor ESR for low current consumption