LMR33620: LMR33620ARNX output load regulation

Rock Shao

Part Number: LMR33620
Other Parts Discussed in Thread: LMR33630ARNXEVM, , LMZM23600, TPS560430, TPS57140-Q1

Hi,

My customer used LMR33630ARNXEVM to modify for 3.3V/0.5A and 5V/0.5A design.

Customer reduces the output capacitance only used one 22uF because of the PCBA space and price, and they found the output voltage regulation was >1% for 0A to 0.5A load regulation, but our competitor MP9994 didn't have this problem and they only used 10uF for output capacitance.

Does there have any solution for reduce this issue? Does TI has any recommend ICs for input voltage between 9~36V, and <1% load regulation? Thanks.

over 4 years ago

0 Harrison Overturf over 4 years ago

TI__Genius 10685 points

Hello Rock,

Which competitor part? I cannot find MP9994.

Where/how did the customer take the Vout measurement?

For best results, the output voltage should be measured directly across the output capacitor using the pigtail method described in the following article:

https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/07/27/how-you-measure-your-ripple-can-make-you-or-break-you

If this does not improve output voltage ripple, the customer can replace the existing 22uF output capacitor with a 22uF, 35V (or greater), X7R.

Regards,

Harrison Overturf

0 Rock Shao over 4 years ago in reply to Harrison Overturf

Expert 2905 points

Hi Harrison,

Excuse me, the competitor part is MP9942.

The customer directly measured the output capacitor with a multimeter and found that the output voltage has a 2% drop value between full load and no load. I think this is caused by the operating mode of the LMR33620. Does TI has any recommend ICs for input voltage between 9~36V, and <1% load regulation? Thanks.

regards

Rock

0 Harrison Overturf over 4 years ago in reply to Rock Shao

TI__Genius 10685 points

Hello Rock,

Has the customer tested multiple LMR33620 devices and noticed the same 2% drop?

Does the MP9942 device consistently have the 1% drop across load?

I also notice that the inductor on the MP9942 EVM has a lower DCR(33mOhm) than the inductor of the LMR33630ARNXEVM (76mOhm). This increased DCR leads to more conduction losses which will become more apparent at higher currents.

The customer should evaluate both devices with the same BoM to so that the comparison is more 1:1 and less dependent upon the variation in passives.

Regards,

Harrison Overturf

0 Harrison Overturf over 4 years ago in reply to Harrison Overturf

TI__Genius 10685 points

Hello Rock,

Here are some other options if load regulation <1% cannot be achieved with LMR33630ARNXEVM:

The LMZM23600 module in FPWM mode has load regulation <1% and minimizes solution size.

TPS560430 is the associated converter with the above module and also shows similar performance.

Regards,

Harrison Overturf

0 Rock Shao over 4 years ago in reply to Harrison Overturf

Expert 2905 points

Hi Harrison,

Thanks, I will recommend TPS560430 to the customer for 12V/0.5A application.

Did you have any suggestions, if there need 12V/1A and the load regulation <1% solution?

Regards

Rock

0 Harrison Overturf over 4 years ago in reply to Rock Shao

TI__Genius 10685 points

Hi Rock,

The TPS57140-Q1 (3.5 to 42V, 1.5A) would be a good fit for this, evaluate Figure 63 in the device datasheet to confirm that the provided load regulation will be sufficient for the application.

Regards,

Harrison Overturf

0 Rock Shao over 4 years ago in reply to Harrison Overturf

Expert 2905 points

Hi Harrison,

If there are price considerations, are there any other suggestions? Thanks.

Regards

Rock

0 Harrison Overturf over 4 years ago in reply to Rock Shao

TI__Genius 10685 points

Hi Rock,

I believe the TPS57140-Q1 would be the best fit here according to the <1% output load regulation constraint, however if you'd like to find a lower cost option, try using TI's parametric search feature which I've copied below to compare between similar parts.

https://www.ti.com/power-management/non-isolated-dc-dc-switching-regulators/step-down-buck/buck-converter-integrated-switch/products.html

Regards,

Harrison Overturf

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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LMR33620: LMR33620ARNX output load regulation