CYD04S36V18
feature on the Full Flex Dual-Ports, as the effective output driver impedance is halved when both resistors are populated. The workaround is to remove the resistors on ZQ1L and ZQ1R for the affected devices.
Variable Impedance Matching (VIM)
- PROBLEM DEFINITION The 256-Ball FBGA package substrate design has the ZQ0L pin shorted to ZQ1L and ZQ0R shorted to ZQ1R. The ZQ1L and ZQ1R pins are not internally connected to the die for the affected devices; therefore, when resistors are connected to these pins to ground, the effective output driver impedance for each port is halved.
- PARAMETERS AFFECTED Effective output driver impedance controlled by the VIM circuitry.
- TRIGGER CONDITION(S) If the designer populates resistors for both ZQ0 and ZQ1, the short between ZQ0 and ZQ1 halves the effective impedance seen by the VIM calibrating circuitry.
- SCOPE OF IMPACT Output driver impedance is halved, as the two VIM calibrating resistors are in parallel to ground.
- WORKAROUND Remove ZQ1L and...
