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LMZ14202: Prove stability and/or create Bode Diagram

Part Number: LMZ14202

(Assigned) customer is using LMZ14202 and would like to measure stability over temperature of their particular design.

They have noted the following statements in the datasheet:


“The control architecture for this part is a "constant on-time" or COT. This architecture is based on hysteretic type control but the switching frequency is almost constant. Getting a conventional frequency response plot from this type of architecture can interfere with the control loop operation and lead to incorrect results.


What is the proper way to measure the loop response of this device or otherwise prove/measure stability of the control loop?

They are not interested in simulation or transient response types of analysis.

Thanks!

-Steve

  • Hello

    As mentioned in the data sheet, trying to measure a Bode plot on a COT will most likely disturb the loop and give false readings.

    Load transients are the best way to test the stability of a COT.

    However, if the design follows the data sheet recommendations, then the application will be stable.

    I have attached an application note that may prove helpful.

    Thanks

    5226.snva874.pdf