we use 10 pcs of LTM4646 and 10 pcs of LTM4622 on a big power system. System requires External Synchronization Clock (800KHZ) for all DC/DC.
Now ONLY ONE sync clock 800KHZ is generated from FPGA, and feed to 20 DC/DC in daisy-chain topology. The output current driving strength of FPGA pins is about only 4mA, we are not sure whether it is enough to drive so many DC/DC sync pins.
So we hope to know the pin capacitance of SYNC pin (pin.F3 of LTM4646 and pin.C4) , and we can confirm the total load-capacitance, then decide wehter a buffer IC should be inserted.