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Tool/software:
Dear Tech Support Team,
I hope this message finds you well.
We are currently working with the TPS55288RPMR Buck-Boost Converter IC in our project and have encountered a challenge with the selection of the dithering capacitor value. According to the datasheet, a 10nF capacitor is recommended; however, using this value results in a modulation rate exceeding the specified limit of < 1kHz.
As per datasheet's equation, with the switching frequency resistor value set to 19.1kΩ, maintaining the modulation rate below < 1kHz (specifically taken at 400Hz, 800Hz, or 900Hz) evaluated the value of this dithering capacitor coming in the range of 22 to 24nF. But this range exceeds the datasheet's recommendation.
Could you please clarify if we take the dithering capacitor value in the range of 22 to 24nF, this deviation from the recommended capacitor value will pose any issues for our overall circuit design? Your guidance on this matter would be greatly appreciated.
Find some attachments for your reference & also find our WEBENCH simulation reports.
Thank you for your assistance.
Best regards,
Tech Consultant
RGBSI,
Bangalore- 560027,
Karnataka, India
Hi Arun,
The dithering function is helpful for the EMI performance improvement. 10nF is recommended with fsw=400kHz, if fsw is changed, the DITH cap should also be modified according to the formula(4).
It will not post issue for circuit design and you can disable this function by connecting DITH with GND if EMI is not critical in your system.
BRs,
Bryce