ADC3562: CLKin termination (HCSL)

Kei Kuwahara

Expert 6550 points

Part Number: ADC3562
Other Parts Discussed in Thread: LMK00334

Hello team,

My customer would like to input HCSL clock signal to ADC3562 CLKIN. (AC-coupled)

Do we need termination resistor at the CLKIN of ADC3562?

Best Regards,
Kei Kuwahara

10 months ago

0 Kei Kuwahara 10 months ago

TI__Expert 6550 points

Hello team,

Can anyone answer my question?

Best Regards,
Kei Kuwahara

0 Geoff Roth 10 months ago in reply to Kei Kuwahara

TI__Expert 4480 points

Hi Kuwahara-san,

The customer should not double terminate the lines. Move the 50Ω to ground close to the DC-blocks that are near the input to the ADC3562. This will terminate the line and allow for a DC path the HSCL driver needs.

Regards,

Geoff

0 Kei Kuwahara 10 months ago in reply to Geoff Roth

TI__Expert 6550 points

Hello Geoff-san,

Thank you for your answer!

Do you mean to connect the 50Ω like the figure below?

If this is what you meant, then there is no termination for HCSL driver of LMK00334.

Best Regards,
Kei Kuwahara

0 Geoff Roth 10 months ago in reply to Kei Kuwahara

TI__Expert 4480 points

Kuwahara-san,

There is no DC path for the HCSL driver in that configuration. The resistors need to be on the other side of the DC block.

Regards,

Geoff

0 Kei Kuwahara 10 months ago in reply to Geoff Roth

TI__Expert 6550 points

Hi Geoff-san,

Geoff Roth said:
Move the 50Ω to ground close to the DC-blocks that are near the input to the ADC3562.

I dont understand what you mean by this.

So this configuration is correct? The GND of 50Ω resistors should be close to ADC3562?

Best Regards,
Kei Kuwahara

+1 Geoff Roth 10 months ago in reply to Kei Kuwahara

TI__Expert 4480 points

Kuwahara,

See picture below

Regards,

Geoff

0 Kei Kuwahara 10 months ago in reply to Geoff Roth

TI__Expert 6550 points

Hi Geoff-san,

Thank you for the figure.

Understood completely!

Best Regards,
Kei Kuwahara

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ADC3562: CLKin termination (HCSL)