Why is DVS Required?

Temperature Dependent Dynamic Voltage Scaling Implementation (XAPP1394)

Document ID
Release Date
1.0 English

To enable low core voltage in a -2 speed, industrial temperature grade, or -2LI SKU of a Versal device, a DVS scheme is required for reliable functionality at temperatures below 0oC. This enables -2LI performance over the entire –40oC to 100oC temperature range and broadens the number of applications that can be supported in the industrial temperature range at the low core voltage (-L). The DVS scheme scales the programmable logic core voltage (VCCINT) from 0.7 V to 0.725 V at lower temperatures to maintain the performance without incurring a power penalty at higher temperatures. The scheme uses the System Monitor (SYSMON) located within the platform management controller (PMC) to read the device junction temperature in a regular interval, sampling every 100 ms and changing the voltage as necessary.

When applying DVS to VCCINT, the voltage changes based on the junction temperature, which requires the VCCINT rail to have a dedicated voltage regulator that is not connected to any other power rails within the system. This might include an extra regulator that is required for a minimum rails consolidation but does not impact full power management implementations. Refer to the Power Design Manager (PDM) tool (download at www.xilinx.com/power) for more details on rail consolidation. To change the voltage regulator output voltage, the PMC signals via PMBus or I2C to change the output voltage through voltage regulator module (VRM) register writes. It requires two PMC MIO pins in banks 500/501 for I2C/PMBus. It can also connect to a GPIO to indicate a voltage high or voltage low mode for use cases where an I2C/PMBus master already exists or is unavailable. If your device is designed never to go below 0oC, a -2LE SKU is recommended because the extended temperature range is from 0oC to 110oC.