Refer to the PDF data sheet for device specific package drawings
VREF (ddrx_vref0) is used as a reference by the input buffers of the DDR2 memories as well as the processor. VREF is intended to be half the DDR2 power supply voltage and should be created using a resistive divider as shown in Figure 8-51. Other methods of creating VREF are not recommended. Figure 8-54 shows the layout guidelines for VREF.