USB Hub Design

[madhub]

Hi,
I am using an USB Hub in my PCB design. The Hub requires 3.3V & 1.2V power supplies, a reset & a 24MHz clock. I have given powers & reset to the IC. I am using an external crystal as the Hub has an internal crystal driver circuit. The powers & reset are proper but I am not getting the clock. Is the clock expected now or any other configurations needs to be done? The IC also has a PLLFILT (Phase Locked Loop filter capacitor) pin where an output voltage of 1.8V will come if the internal PLL circuit is configured. I am not getting this output also. Waiting for any kind of help...

With Regards,
Madhusoodana Bairy

 

[4pyros]

What IC are you using?

 

[alec_t]

I am not getting the clock

Does the crystal require additional capacitors? Have you checked the datasheet for the IC?

 

[madhub]

What IC are you using?

It is actually an HSIC (High Speed Inter-Chip)

 

[madhub]

Does the crystal require additional capacitors? Have you checked the datasheet for the IC?

Yes, the crystal needs minimum of 15pF capacitors across it. I have given 18pF capacitors.

 

[picbits]

Are you building this on breadboard or a proper PCB ? If its on breadboard they often have quite a high capacitance so worth looking at that as well.

 

[madhub]

Are you building this on breadboard or a proper PCB ? If its on breadboard they often have quite a high capacitance so worth looking at that as well.

On a PCB, I have tried by mounting 33pF (greater than previous 18pF) as well. But did not get the clock...

 

[4pyros]

It is actually an HSIC (High Speed Inter-Chip)

Can you give us a part number?

 

[madhub]

Can you give us a part number?

Component Part Number
Processor PCIMX6Q6AVT10AA
HSIC USB Hub USB4640-HZH-03
24MHz Crystal ABM8-24.000MHZ-R60-D-1-W-T
USB Power Switch MIC2026-1YM

 

[4pyros]

Do you have a PPL regulater filter cap hooked up?
Do you have a 1meg load across the XTAL leads?
Are you supplying power to all the VDD leads?

 

[madhub]

Yes, for all above questions ...

 

[kubeek]

So after you pull the reset high, the 1.8V regulator does not turn on?
I think you should check your soldering for cold joints or shorts. What current does the IC draw from the 3.3V and 1.2V rails?

 

[madhub]

So after you pull the reset high, the 1.8V regulator does not turn on?
I think you should check your soldering for cold joints or shorts. What current does the IC draw from the 3.3V and 1.2V rails?

Yes, the internal 1.8V regulator is not turning on.
The IC draws such a less current of around 220mA.

 

[kubeek]

Please measure current on BOTH supply rails.