Generate 25MHz waveform with 50% duty cycle

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Last post
Tue, 2021-01-19 15:00
#1
eng-k
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Last seen: 7 months 1 week ago
Joined: 2019-05-21 02:47
Generate 25MHz waveform with 50% duty cycle

Hi,

I intend to use SLG46826V to design a CLK buffer to generate 25MHz waveform with 50% duty circle

however, the output seems not what I' expecting.

Attached is the design with waveforms.

Could you please advise?

Attachment: 
PDF icon SLG46826V.pdf
Device: 
DA14580
Device Number: 
SLG46826V
Wed, 2021-01-20 09:57
ssaravan
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Last seen: 1 year 9 months ago
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Joined: 2019-10-01 13:53
Hi,

Hi,

Thank you for reaching out to us.

The absence of square pulse on the output could be due to the parasitic capacitance.

Push-Pull output, board, socket, and scope probes create the parasitic RC circuit. RC circuit needs some time to be charged. The more components on the way to your scope, the higher capacitance, the bigger time constant (T=R*C).

If you want to see the square pulses you need to program the chip, solder it on PCB, and use the specific equipment, short line with connectors (like SMA connectors) and impedance matching, etc. In simple terms, you may need to decrease the C component from the equation T=R*C. Please let me know if this helps

Kind Regards

Shivani

Wed, 2021-01-20 15:42
(Reply to #2)
eng-k
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Last seen: 7 months 1 week ago
Joined: 2019-05-21 02:47
Hi Shivani,

Hi Shivani,

Thanks for the advise.

Based on your explanation above, can I conclude that the setting of the OSC is correct (the predivider and Output set to 1)?

Thanks

Wed, 2021-01-20 17:15
(Reply to #3)
ssaravan
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Last seen: 1 year 9 months ago
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Joined: 2019-10-01 13:53
Hi,

Hi,

Yes the current setting is right. The CLK predivider and OUT divider can be used if you further want to significantly reduce the value

Kind Regards

Shivani