JAJSVE5 September 2024 DDS39RF12 , DDS39RFS12
PRODUCTION DATA
The total DAC output current is set through the external RBIAS resistor and the COARSE_CUR_A or COARSE_CUR_B and the FINE_CUR_A or FINE_CUR_B registers. There is a switched fullscale current and a static fullscale current. The switched current is divided between DACOUTA/B+ and DACOUTA/B- in proportion to the digital signal value at the DAC. The static current is fixed at the output of each ball DACOUTA/B+ and DACOUTA/B-.
The equation for the DAC switched output current is
where
The static current is a fixed fraction of the switched current
With a 3.6kΩ bias resistor, COARSE_CUR_A or COARSE_CUR_B = 15 and FINE_CUR_A or FINE_CUR_B = 31, IFSSWITCHED is ~ 20.5mA and IFSSTATIC ~ 4.82mA (on each ball + and -). Enabling CUR_2X_EN doubles the currents.