Hi.!
I designed a buck converter with TPS 54218 (200k to 2Mhz). Because of very less Space on PCB I have to shift the switching frequency as high as possible to reduce the size of output inductor and capacitors. I have selected 1.67MHz switching frequency and got the same result as calculated by the design tool (Switcherpro provided by TI).
The recommended output capacitor is (by swticherpro ) C3225XR0J336M.
it (C3225XR0J336M) has its self resonance frequency at 723kHz and capacitance goes rapidly downwards after this frequency. The inductive part will dominate after this frequency. it is not recommended to use capacitors over the self resonance frequency.(refer the attached file for schematics, bom and characteristics of output capacitor.
-Question 1: why switcherpro is not considered this effect ? because the capacitance will be around 5uF @1.67MHz.
There are almost no capacitors with self-resonance frequency higher than 1.67MHz.
How can I overcome with my design (less space)?
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