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TPS92692-Q1: TPS92692 Spread Spectrum Question

Part Number: TPS92692-Q1
Other Parts Discussed in Thread: TPS92692,

Hi TIer,
I have a question about Spread Spectrum for TPS92692.
I saw the datasheet describe as below. May I know the mean is for gate waveform jitter to drive the main MOSFET? ex. the ± 15% oscillator frequency adds in the switching frequency. 

"The TPS92692 and TPS92692-Q1 devices provide a frequency dithering option that is enabled by connecting a capacitor from the DM pin to GND. A triangle waveform centered at 1 V is generated across the CDM capacitor.The triangle waveform modulates the oscillator frequency by ± 15% of the nominal frequency set by an external timing resistor, RT. The CDM capacitance value sets the rate of the low frequency modulation. To achieve maximum attenuation in average EMI scan set modulation frequency ranging from 100 Hz to 1.2 kHz. The low modulating frequency has little impact on the quasi-peak EMI scan. Set the modulation frequency to 10 KHz or higher to achieve attenuation for quasi-peak EMI measurements. The modulation frequency higher than the receiver resolution bandwidth (RBW) of 9 kHz only impacts the quasi-peak EMI scan and has little impact on the average measurement. "

  • Hi John,

    Yes, the switching frequency will have +/-15% variation added, e.g. your nominal switching frequency set at 300 kHz, the switching frequency will range from 255 kHz to 345 kHz when you enabled the spread spectrum. The capacitor on DM pin determines how fast does this 255 kHz to 345 kHz changes.

    Thank you!