1.5.4.4.2 Reference Voltage Input

In this mode, the input interface supports two single-ended modes:

• Local reference input: A reference voltage is connected to the XCVR_REFCLK_N input, which is used for the clock connected to the XCVR_REFCLK_P input. The resulting reference clock is available on the REFCLK0 output (REFCLK1 output is unavailable with local reference input mode).
• Global reference input: This mode allows for two separate reference clock sources, where the XCVR_REFCLK_P input is compared with a global transceiver reference called XCVR_VREF and is output on REFCLK0. The XCVR_REFCLK_N input is simultaneously compared to the same XCVR_VREF reference signal, and the result is output on REFCLK1. In this scenario, each XCVR_REFCLK_P and XCVR_REFCLK_N pins can accept a single-ended clock source. The resulting clock signals are available on REFCLK0 and REFCLK1 outputs, respectively. Internal voltage reference circuitry is included when a reference voltage input is used. No external voltage is required to the reference voltage input (XCVR_VREF) pin, which is internally connected.