Part Number: LMK1C1106
Other Parts Discussed in Thread: LMK1C1104EVM
Simple question, probably a dumb one.
is this device capable of driving 50 ohm loads, i would have planned on using the output signals as 10MHz measurement equipment reference inputs after being outputted through SMA cables.
And if not, would anyone recommend a more suited device if they know of one? thank you all in advance, charlie.
Hello Charlie,
Not a dumb question at all! The LMK1C1106 has an output impedance of 50ohm to avoid any reflections. Therefore, adding a 50ohm extra series resistance will half your swing as the extra 50ohm will act as a voltage divider. Simulation added below:
Best,
Andrea
Thank you Andrea for your reply !
I see, so using the outputs for my application will be sufficiently sufficient :D
what worried me was the output current specified here,
but now i imagine this spec for a CMOS high Impedance interface use case?
i meant this use case :
here the maximum current that should come from the device would be 3.3/50 = 66mA (which goes over the absolute max output current spec of 50mA) maybe i don't quite understand the 50mA maximum continuous output current rating.
At the end of the day i would like to use this device to supply a frequency reference to multiple measurement equipment through coaxial cables, these interfaces are not high impedance but 50Ohm, and i was wondering if this device was suitable for such an application. (ps these outputs also need to be AC coupled though).
Hello Charlie,
Since your load is 50Ω I would suggest you follow the following configuration in your design (p. 8):
This is the same setup we have on the LMK1C1104EVM (same device, less outputs):
I've used this EVM several times with a 50Ω equipment. Therefore, while you add those 100Ω, there should be no problem. This also applies for AC couple as seen below (p. 11)
Best,
Andrea
