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TPS82085: Beat frequency/EMI issues with multiple parts?

Part Number: TPS82085

I am planning to use 10+ TPS82085 parts to supply multiple separated supply rails on a small form factor PCB. I am concerned with the matching fixed switching frequency of these parts on my small PCB. Without a sync pin present, will the slight variations in the switching frequency/phase cause and EMI issues like beat frequencies?

My application is planning to use the enable pins to power sequence the different rails, but some rails will power on at the same time.

Is there a better solution to avoid potential beat frequencies?

Thank you in advance.

  • This is generally ok. These modules are designed for space-constrained applications, many of which have multiple rails/voltages.

    As well, this is not a fixed frequency device. Here is an application note about its DCS-Control topology: www.ti.com/.../slyt531.pdf At light loads, they will be in PFM mode with a lower frequency. And there will be some small variations over load and Vout as well. www.ti.com/.../slyt646.pdf

    A ferrite bead on each input is probably a good idea to block the high frequency noise from each other's switching from coupling into other outputs.

    Finally, if you are open to using different modules, where you are able to, we have other MicroSiP modules with much smaller size and operating at 4-6 MHz. You can look through them at www.ti.com/microsip Basically, these would be options for rails which need less than 1.6A of current.