VU27P/VU29P devices have two additional rails VCCINT_GT_R and VCCINT_GT_L (hereby referred to as VCCINT_GT), in addition to the other rails present on the VU13P device. Some of the existing VCCINT balls are converted to the new VCCINT_GT balls. VCCINT_GT is powered at 0.9V for -3 speed grades, and 0.85V for all other speed grades. The VCCINT_GT rails can be tied to VCCINT/VCCINT_IO/VCCBRAM for all speed grades other than -2LE. For -2LE, with VCCINT at 0.72V, VCCINT_GT should connect to VCCINT_IO/VCCBRAM while VCCINT is powered separately.
Table: VCCINT/VCCINT_IO/VCCBRAM/VCCINT_GT Connection Matrix shows a connection matrix regarding VCCINT and VCCINT_IO/VCCBRAM/VCCINT_GT.
There are three migration scenarios of concern, and each is explained below:
1.Migration from VU13P -1/-2/-3 to VU27P/VU29P -1/-2/-3.
For this scenario, no accommodation needs to be made for VCCINT migration, because VCCINT, VCCINT_IO, VCCBRAM, and VCCINT_GT remain at the same voltage level (0.85V or 0.90V).
2.Migration from VU13P -2LE to VU27P/VU29P -1/-2/-3
For this scenario, two regulators are required. One regulator powers VCCINT, and another regulator powers VCCBRAM/VCCINT_IO. When using the VU13P -2LE, the VCCINT regulator is powered at 0.72V, and the VCCBRAM/VCCINT_IO regulator is powered at 0.85V or 0.90V. When migrating to the VU27P/VU29P -1/-2/-3, VCCINT is now powered at 0.85V or 0.90V just as VCCBRAM/VCCINT_IO and VCCINT_GT is. AMD recommends designing the VCCINT regulator such that it can be easily changed from 0.72V to 0.85V/0.90V via an external interface (such as PMBus) or with a BOM change such as resistor values.
3.Migration from VU13P (any speed grade) to VU27P/VU29P -2LE
This Figure shows a layout example that supports this scenario. Two regulators are required, one for VCCINT and one for VCCBRAM/VCCINT_IO/VCCINT_GT. When using a VU13P device, resistors R9–R16 should be populated while resistors R1–R8 should be unpopulated. When using a VU27P/VU29P -2LE device, resistors R1–R8 should be populated to properly connect VCCBRAM/VCCINT_IO to the VCCINT_GT pins, while resistors R9–R16 should be unpopulated to keep VCCINT at a separate 0.72V.
Note: This solution requires separate PCB planes for VCCINT, VCCINT_GT, and VCCBRAM/VCCINT_IO.
The number of 0W resistors required on the PCB is dependent on the current consumption and capabilities of the resistor device and layout implementation.
