LDO Load test-Oscilloscope Setting

Hari T O0

Hi ,

I am performing a Load test on an LDO.I will be measuring I/P Current,Voltage:O/P Current,Voltage.

In the oscilloscope measure settings I can see MAX,MEAN,RMS,PK=PK etc .In this which one is the most appropriate one for measuring the above parameters and Why.

Regards

Hari

over 7 years ago

0 Eric.Preiss over 7 years ago

TI__Expert 4435 points

Hi Hari,

It depends on the information you are trying to see. Are you measuring static (steady state) or dynamic (transient) loads?
MEAN is sufficient to get the average current and voltage for static loads.
MIN, MAX, Pk-Pk are useful for transient loads.
RMS is often used for ripple, noise, etc.

See SLVA079 application report.
www.ti.com/.../slva079

0 Hari T O0 over 7 years ago in reply to Eric.Preiss

Genius 3820 points

Hi Eric,
I am connecting the output of the LDO to an ELOAD and vary the current from no load to 1A and will measure I/P voltage,Current ::O/P voltage and current.We can call ELOAD as static,please correct me if I am wrong.
Regards
Hari

0 Eric.Preiss over 7 years ago in reply to Hari T O0

TI__Expert 4435 points

Hi Hari,

Yes, I agree that would be a static load test.

0 Hari T O0 over 7 years ago in reply to Eric.Preiss

Genius 3820 points

Hi Eric,
Mine is a 5V to 1.5V LDO. Imagine I Put RMS in oscilloscope setting and consider I am getting a value of 1.534.May I know is this value contains noise also.
Simply putting RMS in oscilloscope will give us noise values?Is this a correct method to measure LDO output noise.

Regards
Hari

0 Eric.Preiss over 7 years ago in reply to Hari T O0

TI__Expert 4435 points

Hi Hari,

Measuring LDO noise takes a few more steps. See this app note from TI:
www.ti.com/.../slyy076.pdf

For further reference, please see this index of LDO app notes:
www.ti.com/.../sbva026e.pdf

0 Hari T O0 over 7 years ago in reply to Eric.Preiss

Genius 3820 points

Hi Eric,

Thanks.What I understood is that simply putting RMS in oscilloscope won't give you proper noise information.Please correct me if I am wrong.

Regards
Hari

0 Eric.Preiss over 7 years ago in reply to Hari T O0

TI__Expert 4435 points

Hi Hari,

Your questions seem focused on measurement techniques. I recommend you look at an oscilloscope manufacturer's website for further help on understanding and making measurements.

Power management

Power management forum

LDO Load test-Oscilloscope Setting