LMX2820: OSCIN_P/N Pin

Takafumi Shimizu

Prodigy 20 points

Part Number: LMX2820

Please tell me the internal circuit (internal connection) of OSCIN_P(Pin.8) and OSCIN_N(Pin.9).

over 3 years ago

0 Julian Hagedorn over 3 years ago

TI__Mastermind 20900 points

Hello,

The input is high impedance and requires AC-coupling caps at the pin. A CMOS clock or XO can drive the single-ended OSCIN pins. Differential clock input is also supported.

Example input terminations:

Regards,

Julian

0 Takafumi Shimizu over 3 years ago in reply to Julian Hagedorn

Prodigy 20 points

Hello,

Thank you for answering.

Is the OSCIN_N pin in the middle of Example input terminations correct to open? Or is it 50Ω?

What is the internal circuit from the OSCIN_P pin and OSCIN_N pin to differential single conversion?

0 Noel Fung over 3 years ago in reply to Takafumi Shimizu

TI__Guru** 107030 points

Hi Shimizu-san,

With single-ended input, you could connect the input clock to one of the pins, either _P or _N pin. The unused pin should be AC-coupled to the ground directly or via a 50Ω resistor.

What specific information you are looking for from the internal OSCin circuit?

0 Takafumi Shimizu over 3 years ago in reply to Noel Fung

Prodigy 20 points

Hi,

I would like to know the circuit configuration inside the IC for input terminations design to OSCIN_P pin and OSCIN_N pin.

0 Noel Fung over 3 years ago in reply to Takafumi Shimizu

TI__Guru** 107030 points

Hi Shimizu-san,

The input pins are biased to a certain voltage with a few kΩ resistors, that's why AC-couple is needed.

Clock & timing

Clock & timing forum

LMX2820: OSCIN_P/N Pin