We are using the USB hub controller "TUSB2046BVFRG4" in our design, and for providing clock we are using FOX crystal 6MHz. The start-up time taken by crystal is too long about 1.01sec (start-up time). We need to decrease the start-up time to 200ms as per the requirement.
Is the crystal start-up time is determined by USB Hub controller internal circuit?
Is there any FLL inside the hub to determine the start up time of crystal?
Images showing the snapshot of Oscilloscope, displaying Power rail vs reset and power rail vs Clock.
Hello Sivasuryan,
Your power on reset pulse is too long. The TUSB2046 requires a reset pulse of between 100 us to 1 ms after Vcc (3.3-V) reaches its 90% (see the below power-up sequence). If the recommended external RC circuit is installed (15K pull-up resistor and 1 uF cap) then the reset will be held low for somewhere within the 100 us to 1 ms range. Anything less than 100 us is too short for the device and anything longer than 1 ms can interfere with USB enumeration (mainly an issue for embedded systems). 
Regards,
Joel
