Refer to the PDF data sheet for device specific package drawings
Like DDR_VREF, the nominal value of the VTT supply is half the DDR3 supply voltage. Unlike DDR_VREF, VTT is expected to source and sink current, specifically the termination current for the ADDR_CTRL net class Thevinen terminators. VTT is needed at the end of the address bus and it should be routed as a power subplane. VTT should be bypassed near the terminator resistors.