Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
8 years ago

MAX V GCLK Impedance

Hi, I'm using a MAX V device with a 100Mhz CLK on the GCLK input. We need to understand the impedance of the GCLK input such that we can match the crystal oscillator module to the MAX V input. In the...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
8 years ago

The specified input capacitance is the pin impedance you are asking for.

Source side series termination should be considered for longer traces, e.g. > 50 - 100 mm. If this applies to your design, supplement a series resistor that adds up to internal 25 ohms for a total impedance equal to the trace impedance.