USB Hub IC Not Generating 24MHz Clock or 1.8V PLLFILT Output—Possible Reasons?

A USB Hub IC requiring 3.3V and 1.2V supplies, reset, and a 24MHz clock is not generating the expected clock output or the 1.8V PLLFILT voltage from its internal PLL circuit. The user provided power and reset signals correctly and used an external 24MHz crystal with the Hub's internal crystal driver. The Hub is an HSIC USB Hub (USB4640-HZH-03) connected to a processor (PCIMX6Q6AVT10AA) and powered by a USB power switch (MIC2026-1YM). The crystal used is a ceramic type (ABM8-24.000MHZ-R60-D-1-W-T) with 18pF load capacitors as recommended in the USB4640 datasheet. The discussion highlighted the need for schematic review and proper component values, especially the crystal load capacitors, to ensure correct PLL operation and clock generation. The absence of the 1.8V PLLFILT output suggests PLL configuration or hardware issues. Further detailed schematic and block diagram review was requested but limited by confidentiality. The ceramic crystal and capacitor values were questioned as potential causes of the problem.
Summary generated by the language model.