LM5150-Q1: Clarification for the equation - 38

SAQUIB MANSOOR

Prodigy 20 points

Part Number: LM5150-Q1

Hi Texas,

In the Datasheet, LM5150-Q1 (SNVSAP6 –SEPTEMBER 2017).

I need the clarification on the Equation No. 38 (Pg. No. 28)

For calculating the Resr(max) for the output capacitor, Ccomp and Fcross is used.

As per example,

Ccomp = 33nF

Fcross = 2.27K

Resr(max) = 23mohm but with calculation I got 212 ohm.

Moreover, in example Ccomp is used as 330uF instead of 33nF. Is this is a mistake or it is correct?

So, kindly confirm the equation with the unit to be used. Attached the datasheet screenshot for reference

over 5 years ago

0 Youhao Xi over 5 years ago

TI__Guru* 78070 points

Hi Saquib,

Thank you for considering the LM5150. It is obviously a typo. The 330uF is correct but it is Co not CCOMP. Anyway, I get this to our datasheet writer's attention. He should respond soon.

Thanks,

Youhao Xi, Applications Engineering

0 SAQUIB MANSOOR over 5 years ago in reply to Youhao Xi

Prodigy 20 points

So, the final conclusion is like,

Equation 38, relates to the output capacitor (Co) and not the Compensator capacitor (Ccomp).

Equation 38 will be : 1/(2*pi*Co*Fcross*10).....Am i right?

Other attention :

If the above formula is correct and Co=330uF, then Resr(max) will be approx 21.25 mohm and not 23 mohm as mentioned in datasheet....Just for information

0 EricLee over 5 years ago in reply to SAQUIB MANSOOR

TI__Guru 58171 points

In progress, I will close this thread.

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LM5150-Q1: Clarification for the equation - 38