A typical CMOS gate combined with a PCB trace have a load of approximately 10 pF. Therefore, as each bit switches, 10 mA(10pF×1V÷1ns) of dynamic current per bit flow in or out of the device. A full-scale transition can cause up to 140 mA(14 bits × 10 mA/bit) of current to flow through the output stages. The series resistors should be placed as close as possible to the AD6644 to limit the amount of current that can flow into the output stage. These switching currents are confined between ground and the DVCC pin. Standard TTL gates should be avoided because they can appreciably add to the dynamic switching currents of the AD6644. Note that extra capacitive loading increases output timing and invalidates timing specifications. Digital output timing is guaranteed with 10 pF loads. If the analog input range is exceeded, the overrange (OVR) bit toggles high and the digital outputs retain their respective positive or negative full-scale values.