SNAU310 June 2024 LMKDB1102 , LMKDB1202
3.1.3 Clock Input
LMKDB1x02 can support different input interfaces for CLKIN# depending on the input swing and common mode voltage. There are four input interfaces type that can be configured on LMKDB1x02 using external components and internal termination schemes as shown in Figure 4-1. If using a signal generator and the LMKDB1102, then make sure to populate R16 with a 100Ω resistor or use internal / external 50Ω termination to ground. If using a signal generator, the LMKDB1202, and CLKIN1, also populate R24 with a 100Ω resistor or use internal / external 50Ω termination to ground.
- DC Coupled HCSL / LP HCSL Input.
- DC Coupled LVDS Input.
- External AC Coupled Input.
- Internal 50Ω to ground terminations.
Figure 3-1 Input InterfacesTable 4-6 outlines how to setup all different interfaces supported by LMKDB1x02.
| Input Interface | Configuration |
|---|---|
| DC coupled HCSL / LPHCSL (default) | This is the default for the EVM for both clock inputs. R15, R18 and/or R23, R25 values are 0Ω and Input Interface Type on Input page is selected to DC Coupled for each input being used. R23 and R25 are only required if using the CLKIN1 pins of the LMKDB1202. |
| DC coupled LVDS input | Populate R16 and/or R24 with a 100Ω resistor and set Input Interface Type on Input page to DC Coupled for each DC coupled LVDS input. R24 is only required if using the CLKIN1 pins of the LMKDB1202. |
| External AC coupled input | Replace R15, R18 and/or R23, R25 with 0.1uF capacitor and set Input Interface Type on Input page to AC Coupled for each external AC coupled input. R23 and R25 are only required if using the CLKIN1 pins of the LMKDB1202 |
| Internal termination | To enable internal 50Ω to ground terminations. Set the Input Termination on Input page to Enabled. |