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Hardware Interfacing of AD9211 Control Pins

Question asked by mahawarp on Jul 21, 2011
Latest reply on Jul 23, 2011 by mahawarp

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.