In datasheet of AD9211(attached below), on page No.23, it is written that "All serial pins(SCLK/DFS, SDIO/DCS) are inputs with an open-drain configuration and should be tied to an external pull-up or pull-down resistor (suggested value of 10 kΩ)".
1. Does open-drain configuration ever has pull-down register? It should always has a pull-up register?
2. Figure 35. 'Equivalent SCLK/DFS, RESET, PWDN Input Circuit' and Figure 36 'Equivalent SDIO/DCS Input Circuit' in the same datasheet are not showing that these pins are open-drain.
Above matter has a big contradiction, please resolve it.