Powering the XEM8370

The XEM8370 requires a clean, filtered, DC supply within the range of 5 V to 18 V. This supply may be delivered through the DC power connector (rated to 5 A max current) or through the expansion connectors (rated to 16 A max current).

The XEM8370 power distribution system is quite complex, with several supplies designed to provide suitable, efficient power for several systems and modules. A block diagram of the system follows, with input (+VDC) shown to the left and accessible supply rails shown to the right.

Supply Heat Dissipation (IMPORTANT!!)

Due to the limited area available on the small form-factor of the XEM8370 and the density of logic provided, heat dissipation may be a concern. This depends entirely on the end application and cannot be predicted in advance by Opal Kelly. Heat sinks may be required on any of the devices on the XEM8370. Of primary focus should be the FPGA (U10) and SDRAM (U16, U17). Although the switching supplies are high-efficiency, they are very compact and consume a small amount of PCB area for the current they can provide. The VCCINT regulator (U20) may require airflow if the FPGA is using close to its 40A rating.

If you plan to put the XEM8370 in an enclosure, be sure to consider heat dissipation in your design.

FPGA heatsink information is provided on the FanSink

Power Supply

The XEM8370 is designed to be operated from a single 5-18 V power source supplied through a DC power connector on the device. This provides power for the several high-efficiency switching regulators on-board to provide multiple DC voltages for various components on the device as well as three adjustable supplies for the I/O levels. Status monitoring for many of these rails is available in the Device Sensors.

DC Power Connector

There are two DC power connections on the XEM8370. The barrel jack connector and the VDC pins of the expansion connector.

The barrel jack is part number PJ-102AH from CUI, Inc. It is a standard “canon-style” 2.1mm / 5.5mm jack. The outer ring is connected to DGND. The center pin is connected to +VDC. This jack is capable of 5 A maximum continuous current.

Applications requiring higher current must use the expansion connectors for providing power to the system (rated for a maximum of 16 A). See the pins list for the VDC connected expansion connector pins.

Over-Voltage Protection and Under-Voltage Lockout

The XEM8370 includes an over-voltage protection circuit which disconnects the input supply from the on-board circuitry when the input is higher than approximately 18.4 V. It is also prevented from powering on when the input supply is below approximately 4.5V. And it is protected from reverse polarity voltage connected to the input.

Bank I/O Power

The XEM8370 includes 3 on board adjustable regulators that power different I/O bank rails. The available I/O are distributed across these rails to allow for connections to multiple voltage domains. For more information on configuring the adjustable voltage regulators see the Device Settings page.

VIO188 and 89VCCO_88_89
VIO267, 68 and 69VCCO_67_68_69
VIO364 and 66VCCO_64_66

LED Indicators

The XEM8370 includes two LED indicators for power status.

PWR IN (D11)+VDCIN present, no over-voltage or reverse voltage faults
PWR GOOD (D12)All on-board power supplies active and within expected range
(Does not include VIOx supplies)

Power Budget

The table below can help you determine your power budget for each supply rail on the XEM8370. All values are highly dependent on the application, speed, usage, and so on. Entries we have made are based on typical values presented in component datasheets or approximations based on AMD power estimator results. Shaded boxes represent unconnected rails to a particular component. Empty boxes represent data that the user must provide based on power estimates.

The user may also need to adjust parameters we have already estimated (such as FPGA Vcco values) where appropriate. All values are shown in milliwatts (mW). Note that this table does not include the two supplies dedicated to the GTH transceivers. These are independent and can be computed separately for power budget based on their assigned function.

COMPONENT(S)0.85 V0.9 V1.2 V1.2 V1.8 V3.3 VVIO1VIO2VIO3
Fabric Oscillator55
FX3 USB Host Interface490
DDR4 VTT Termination460
FPGA VCCO65 (USB Host Interface)25
FPGA VCCO70 + VCCO71 (1.2V DDR4)230
Total (mW)1350317013201645100
Available (mW)34,0002,7003,6002,40014,4006,6002000 mA
2000 mA
2000 mA

Example XEM8370-KU11P FPGA Power Consumption

AMD XPower Estimator 2020.1.1 was used to compute the following power estimates for the Vccint supply. These are simply estimates; your design requirements may vary considerably. The numbers below indicate approximately 80% utilization.

Clock200 MHz GCLK, 400,000 fanout1,132
Clock300 MHz GCLK, 140,000 fanout954
Clock200 MHz SR, 50,000 fanout258
Logic200 MHz, 90,000 logic LUTs, 50,000 shift registers, 50,000 distributed RAMs, 350,000 registers3,367
Logic300 MHz, 50,000 logic LUTs, 140,000 registers1509
Logic1200 MHz (DDR4), 8000 logic LUTs383
BRAM18-bit, 200 MHz, 500 block RAMs, 12.5% toggle rate228
BRAM36-bit, 200 MHz, 250 block RAMs, 12.5% toggle rate226
DSP200 MHz, 2500 slices, 12.5% toggle rate2,299
GTH20 channels, 12.5 Gb/s767
GTY8 channels, 16.375 Gb/s425
Misc.DCM, PLL, VCCINT_IO, etc.500
Total12,048 mW
Available38,000 mW