AM6442: CLKIN source of crystal and oscillator

Tony Tang

Part Number: AM6442

There are two source of CLIN, one is crystal, another is oscillator on EVM.

For customer board, keep anyone is OK?

Is there any limitation of use crystal or oscillator?

0 Shriram Moharil over 4 years ago

Hi Tony,

Can you clarify what does the picture on the right show? Is that from a customer board?

regards,

-Shriram

0 Tony Tang over 4 years ago in reply to Shriram Moharil

second version EVM.

Current EVM also have two CLKIN source, just a little difference, currently use a CDC clock device.

0 Shriram Moharil over 4 years ago in reply to Tony Tang

Ok. thanks for clarifying.

Will look into this and get back to you.

regards,

-Shriram

0 Shriram Moharil over 4 years ago in reply to Shriram Moharil

Hi Tony,

Here are some trade-offs between using crystals and oscillators:

Oscillators combine the crystal and resonator/amplifier circuit together so they tend to be more expensive then equivalent performance crystal

Oscillators designed to directly feeding PLL or clock distribution circuits on PCB
AM64x have the resonator/amplifier circuit built in to enable lower cost crystal usage

Some oscillators like temperature compensated oscillators (TCXO) include a resistive heating element that will raise the temperature of the case above some point where variability of the frequency across process is mostly nulled out
Voltage controlled (VCXO) or voltage controlled, temperature compensated (VCTCXO) also include a voltage bias control that can be hooked up to a DAC to allow for feedback control of the reference frequency

regards,

-Shriram

0 Tony Tang over 4 years ago in reply to Shriram Moharil

shriram,

Thanks for background sharing. so either works for AM644x?

0 Shriram Moharil over 4 years ago in reply to Tony Tang

Tony,

Yes that would depend on the customer preference for their specific system.

regards,

-Shriram

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