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USB hosts hubs transceivers

HCJung
Level 1
5 sign-ins First solution authored First reply posted
Level 1

Hello, 

I have a question about the external X-tal load capacitance for CY7C65631-56LTXI USB hub.

I have one or two downstream(thermal cam module or Iris AI module), and it is designed as a self powered mode.

I am using the Android system.

The product is assembled in one piece and is always connected.

I found a some issue that the USB hub is not recognized when booting for the first time.

Not all sets are like that, and it occurs in some samples. When resetting is added by host AP side, it is recognized, but there are some samples that are not.

So I was suspicious of the x-tal design side, so I checked the product specifications.

According to a document Number 001-52934 Rev. *J, there are only comment as below.

---------------------------------------------------------------------------------

Oscillator or Crystal Frequency (FOSC),
parallel resonant,
12-pF load capacitance, 0.5 mW ................ 24 MHz ± 0.05%

---------------------------------------------------------------------------------

Looking at the schematic of CY4606, it is used an eCERA's FX2400026 X-tal. Is it necessary to use only products with similar specs? 

I am using the product as the attached document, but please check if there is a problem with the specification.

and an external capacitance is 18pF.

 

Thanks,

Jung

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1 Solution
HCJung
Level 1
5 sign-ins First solution authored First reply posted
Level 1

Hi Mallika,

Thanks for your reply.

I tested a other x-tal, but it wasn't the hub enumeration on the host.

Clock is OK. But It seems that the host side does not recognize the pullup of the USB line.

I added a pull up resistor on the D+, only then does the host start to react.

I've tried connecting it to a Windows PC and it's the same.

So, I have requested an analysis related to the current problem to a parts dealer in Korea.

Thank you for your kind response, and if there is an update,

I will post additionally. I will close this issue for now.

 

Thanks,

Jung

 

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6 Replies
MallikaK_22
Moderator
Moderator 250 solutions authored 500 replies posted 250 replies posted
Moderator

Hi Jung,

I think that if the crystal can oscillate at 24MHz with 18pF capacitor, it should not be an issue.

On the other hand, the issue could be because of the drive level of the crystal. As per the HX2LP datasheet, HX2LP should use a 500uW drive level crystal. But this is not satisfied by the crystal you are currently using.

Regards,

Mallika

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HCJung
Level 1
5 sign-ins First solution authored First reply posted
Level 1

Hello Mallika,

Thank for your answer about my question.

I checked the X-tal's oscillation clock, please see the attached document.

Is this a problem that can only be solved by using the drive level crystal as you recommended?

Thanks,

Jung

 

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MallikaK_22
Moderator
Moderator 250 solutions authored 500 replies posted 250 replies posted
Moderator

Hi Jung,

Yes, I suspect it could be because of the improper drive level. We have seen such issues before because of not using the recommended drive level.

Regards,

Mallika

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HCJung
Level 1
5 sign-ins First solution authored First reply posted
Level 1

Hi Mallika,

Thanks for your answer.

I checked that it was changed with other xtal, but issue is not cleared.

Would you like to check the spec document please?

After Enumeration with the host is normally completed (when there is no client),

the Xtal clock is turned off.

Otherwise, the clock keeps oscillating.

It seems that the AP and enumeration are not working well.

I hope you can give me some advice on which points to check additionally.

Thanks,

Jung

 

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MallikaK_22
Moderator
Moderator 250 solutions authored 500 replies posted 250 replies posted
Moderator

Hi Jung,

Apologies for the delay in response.

After changing the crystal, is the hub enumerating on the host?

For HX2LP, the oscillator will turn on only when upstream is connected. If no upstream is there, the oscillator will switch off. In case if upstream is connected but no downstream port is connected, the oscillator will switch off after some time.

Regards,

Mallika

HCJung
Level 1
5 sign-ins First solution authored First reply posted
Level 1

Hi Mallika,

Thanks for your reply.

I tested a other x-tal, but it wasn't the hub enumeration on the host.

Clock is OK. But It seems that the host side does not recognize the pullup of the USB line.

I added a pull up resistor on the D+, only then does the host start to react.

I've tried connecting it to a Windows PC and it's the same.

So, I have requested an analysis related to the current problem to a parts dealer in Korea.

Thank you for your kind response, and if there is an update,

I will post additionally. I will close this issue for now.

 

Thanks,

Jung

 

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