CY7C65621 , suitable crystal

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nimu_4164261
Level 1
Level 1

hi all.

in the

CY7C65621 usb2 hub, the criteria for suitable crystal is unclear - page 22  12pf,500uW crystal. 24Mhz is o.k.understood,

but 12pF, and 500uW ??

is this are the maximum ratings or the exact required ratings of the crystsal ?, because 500uW is very rare power consumption to find available this days - 10-100uW (maybe 200uW) is o,k  but 500uW also 12pF if i will find less 8-10pF?

please advise.

thx.

nitsan.

 

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1 Solution
Sananya_14
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi Nitsan,

The crystal ratings are the maximum ratings which means we recommend a 500uW crystal to make sure power dissipation does not exceed the drive level of the crystal and 12pF is only a recommended value which satisfies the drive level equation.

Best Regards,

Sananya

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3 Replies
Sananya_14
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi Nitsan,

The crystal ratings are the maximum ratings which means we recommend a 500uW crystal to make sure power dissipation does not exceed the drive level of the crystal and 12pF is only a recommended value which satisfies the drive level equation.

Best Regards,

Sananya

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hi Sananya .

so  a 100uW/9pF crystal should work fine with thre CY7C65621/31 items ?

thx.

nitsan.

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Please use the equations. Our recommended values are only a starting point to help arrive close to the crystal that will satisfy both power dissipation and load capacitance equations. The power equation will also take into account ESR of the crystal which could be different for crystals with same drive-level and capacitance.

Regards,

Rajath

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