Powering the XEM8320

The XEM8320 requires a clean, filtered, DC supply within the range of 8 V to 14 V. This supply may be delivered through the barrel jack power connector (rated to 5 A max current) or through the 6-pin power connector (rated to 24 A max current).

The included fansink has a nominal operating voltage of 12 V and a recommended operating range of 10.8 V to 13.2 V. The fansink is powered directly by the external power supply connected to the XEM8320. It is recommended to keep the external supply voltage within this range whenever the fansink is enabled.

Supply Heat Dissipation (IMPORTANT!!)

Due to the limited area available on the small form-factor of the XEM8320 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 XEM8320. Of primary focus should be the FPGA (U11) and SDRAM (U16). 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.

FPGA heatsink information is provided on the Specifications Page

Power Supply

The XEM8320 is designed to be operated from a single power supply of 8 V to 14 V supplied through either of the two DC power connectors 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 software adjustable supplies for the SYZYGY peripherals.

A block diagram of the power distribution system is shown below.

The fansink included with the XEM8320 has an operating range of 10.8 V to 13.2 V, with a nominal operating voltage of 12 V. It is recommended to keep the external supply voltage within this range whenever the fansink is enabled.

Barrel Jack Power Connector

The barrel jack power connector on the XEM8320 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 +VDCIN_JACK.

The PJ-102AH jack is rated for 5 A maximum continuous current. Applications requiring higher current are advised to use the 6-pin connector for providing power to the system (rated for a maximum of 24 A).

6-Pin Power Connector

The 6-pin connector is a PCIe-style power connector from Molex, part number 0455580003. Pins 1-3 are connected to +VDCIN_JACK, and pins 4-6 are connected to ground. Maximum current is 24 A (8 A per pin).

Over-Voltage Protection and Under-Voltage Lockout

The XEM8320 includes an over-voltage protection circuit which disconnects the input supply from the on-board circuitry when the input is higher than approximately 15.0 V. It is also prevented from powering on when the input supply is below approximately 7.25V. This is determined by the startup voltage of the VCCINT regulator (U21, Murata MYMGM1R816ELA5RA). And it is protected from reverse polarity voltage connected to the input.

LED Indicators

The XEM8320 includes five LED indicators for power status.

LEDOn Condition
PWR IN (D11) +VDCIN present (>4V), no over-voltage or reverse voltage faults
PWR GOOD (D10)All on-board power supplies active and within expected range
(Does not include +3.3V_SZG, +5V_SZG, and VIOx supplies)
VIO1 (D13) VIO1 power supply enabled
VIO2 (D14) VIO2 power supply enabled
VIO3 (D15) VIO3 power supply enabled

SYZYGY Power Sequencing

Power to the +5V and +3.3V SYZYGY rails are enabled shortly after power-on. Voltage and timing of powering the VIO rails on the three SYZYGY power groups depends on the XEM8320_SMARTVIO_MODE device setting. See the SYZYGY Ports documentation for more information.

Power Budget

The table below can help you determine your power budget for each supply rail on the XEM8320. 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) unless otherwise specified.

COMPONENT(S)0.85 V1.2 V1.8 V S11.8 V S23.3 V
Clock oscillators287
FX3 USB host interface468180
DDR4 VTT termination461
FPGA VCCO 180 16
Total (mW) 956 6,770 1,170
Available (mW)13,6002,4008,1003,6006,600
SYZYGY Group 1
SYZYGY Group 2
SYZYGY Group 3
Total (mW)
Available (mW)14,85022,5001000 mA
1.0-1.8 V
1000 mA
1.2-3.3 V
1000 mA
1.2-3.3 V

Note: VIO1 + VIO2 + VIO3 total power must not exceed 22,500 mW. These regulators share the output of an intermediate 5V step-down regulator.

Example FPGA Power Consumption

AMD Power Estimator (XPE) version 2020.2.2_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, 200,000 fanout986
Clock300 MHz GCLK, 75,000 fanout628
Clock100 MHz GCLK, 100,000 fanout272
Clock667 MHz GCLK, 50,000 fanout963
Logic200 MHz, 58,000 logic LUTs, 20,000 shift registers, 20,000 distributed RAMs, 150,000 registers1,566
Logic300 MHz, 8,000 logic LUTs, 75,000 registers583
Logic667 MHz (DDR4), 16,000 logic LUTs, 50,000 registers1,149
BRAM18-bit, 200 MHz, 280 block RAMs, 50% toggle rate519
BRAM36-bit, 300 MHz, 140 block RAMs, 50% toggle rate920
DSP300 MHz, 1090 slices, 12.5% toggle rate1,503
GTY11 channels, 16.3 Gb/s727
Misc.DCM, PLL, VCCINT_IO, etc.100
Total9,916 mW
Available13,600 mW