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Chip Enable/Standby

The chip can be enabled or put into standby mode by setting jumper JP9. In standby mode the current usage drops to

<1nA for ultra low power standby. This pin is internally pulled low so removal of the shunt will automatically put the chip

in standby mode. To enable the chip place the shunt jumper across JP9(1-2).

External Reference Input

It is possible to input a custom reference frequency if it is not available as a standard crystal frequency. A test point is

provided to apply this frequency from an external source such as a low phase noise RF signal generator. The crystal

must be removed to inject this signal. Add .01uF capacitors to C5 and C10 and insert a 0-Ohm, 0603 resistor at C4.