TPS62420: Mega Hertz range emission from switching IC

Hello Sooraj,

thanks for reaching out in E2E.

If this spectrum is measured at the output then you can add low value ceramic capacitors (0.1uF, 0.01uF, 0.001uF, etc). If more filtering is required then a second stage filter as described in this application note "Using the Filters with the DC/DC Step-Down Converter" will reduce the voltage ripple. Alternatively you can add an LDO at the output.

Best regards,

Andreas.

Hello Sooraj,

thanks for letting me know which kind of emission is causing the problems. For radiated emission the layout is a critical step, to minimize high dI/dt current loops. Therefore the input and output caps should be placed as close as possible to the IC. The GND return path of these caps is also important (as short as possible and in a star topology with the thermal pad of the IC in the middle). Please refer to section 11 in the datasheet for layout guidelines. You can find an example layout in section 11.2 of the datasheet and in section 3.1 of the TPS624xxEVM-167 User Guide. You can also try to use shielded inductors or complete shielding of the converter circuit.

The following application notes will provide more details on EMI optimization in general.

• "Layout Tips for EMI Reduction in DC/DC Converters"
• "EMI/RFI Board Design"
• "Simplify Low-EMI Design with Power Modules"

Best regards,

Andreas.