ZHCSK16A October 2017 – July 2019 LMK04228
PRODUCTION DATA.
The CLKin pins of the LMK04228 can be driven using a single-ended reference clock source, for example, either a sine wave source or an LVCMOS/LVTTL source. Either AC coupling or DC coupling may be used. In the case of the sine wave source that is expecting a 50-Ω load, TI recommends that AC coupling be used as shown in the circuit below with a 50-Ω termination.
NOTE
The signal level must conform to the requirements for the CLKin pins listed in Electrical Characteristics. CLKinX_BUF_TYPE is recommended to be set to bipolar mode (CLKinX_BUF_TYPE = 0).
If the CLKin pins are being driven with a single-ended LVCMOS/LVTTL source, either DC coupling or AC coupling may be used. If DC coupling is used, the CLKinX_BUF_TYPE should be set to MOS buffer mode (CLKinX_BUF_TYPE = 1) and the voltage swing of the source must meet the specifications for DC-coupled, MOS-mode clock inputs given in Electrical Characteristics. If AC coupling is used, the CLKinX_BUF_TYPE should be set to the bipolar buffer mode (CLKinX_BUF_TYPE = 0). The voltage swing at the input pins must meet the specifications for AC-coupled, bipolar mode clock inputs given in Electrical Characteristics. In this case, some attenuation of the clock input level may be required. A simple resistive divider circuit before the AC-coupling capacitor is sufficient.