I'm using the LTC3130 for DC-DC conversion. The datasheet says that the capacitors around the inductor, at pins BST1 and BST2, should be 22nF. I'm curious, why is 22nF recommended for these capacitors?
The BST caps provide charge to the gate drivers to turn-on the internal switches as well as provide the steady state current required for the driver and level shift circuits. Typically the BST caps are sized to provide the current required for a desired ripple voltage, at the given switching frequency.
22nF is the recommended value to ensure adequate drive over the full range of operation.
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