Powering the XEM7360

The XEM7360 requires a clean, filtered, DC supply within the range of 4.5 V to 5.5 V. This supply may be delivered through the DC power connector (rated to 5 A max current) or through the mezzanine connectors (rated to 8 A max current).

The XEM7360 power distribution system is rather complex, with several supplies designed to provide suitable, efficient power for several systems and modules. A schematic 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 XEM7360 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 XEM7360.  Of primary focus should be the FPGA (U7) and SDRAM (U10, U11, U12, U13).  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.

If you plan to put the XEM7360 in an enclosure, be sure to consider heat dissipation in your design.

Power Supply

The XEM7360 is designed to be operated from a single 5-volt power source supplied through the DC power jack 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 peripheral.

DC Power Connector

The DC power connector on the XEM7360 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.

Powering via USB

Note: Read this section carefully before applying this technique. The XEM7360 power consumption depends greatly on the FPGA and device configuration and could easily exceed available power from USB.

The XEM7360 has been designed to accept power (+5VDC only) via the USB connector with a small modification. To power from USB, you will need to install a 0 Ω resistor (0402 dimension) at location R39, located on the reverse side of the PCB under the power connector. This will connect the +5VUSB from the USB connector to the +5VDC on the XEM7360.

With this resistor in place, you should not apply +5VDC to the external power connector.

Power Budget

The table below can help you determine your power budget for each supply rail on the XEM7360.  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 Xilinx 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 GTX transceivers. These are independent and can be computed separately for power budget based on their assigned function.

COMPONENT(S)1.0V1.2V1.5V1.8V2.0V3.3V
200 MHz231
USB, DDR33103,0002,970
FPGA Vccint, Vccbram
FPGA Vccaux2439
FPGA Vccaux_io120
FPGA Vcco33,34 (DDR3), est.273
FPGA Vcco14 (USB), est.216
FPGA Vcco
Total (mW)
Available (mW)15,00048013,5005,4008006,600

Example XEM7360-K160T FPGA Power Consumption

XPower Estimator version 14.3 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.

COMPONENTPARAMETERSVCCINT
Clock250 MHz GCLK, 163,237 fanout716 mW
Logic (DFF)250 MHz, 162,240 DFFs1,322 mW
Logic (LUT)250 MHz, 81,120927 mW
BRAM18-bit, 517 @ 250 MHz674 mW
DSP250 MHz, 480 slices605 mW
Memory Controller1600 Mb/s, DDR37 mW
GTXAurora, 8 lanes, 8 Gb/s458 mW
Misc.DCM, PLL, etc.5 mW
Total4,714 mW
Available6,000 mW

Heatsink

The device has been fitted with two heatsink anchors, proximate to the FPGA for mounting a passive or active heat sink. The following heat sink has been tested with the XEM7360.

MANUFACTURERPART NUMBERDESCRIPTION
Opal Kelly IncorporatedFANSINK-30X30-MCCustom with fan mount

The active heat sink above was custom built based on design specifications provided by Opal Kelly to mate to the XEM7360. It includes a small fan which connects to the fan controller on-board for manual or automatic fan speed control. It is available for purchase directly from Opal Kelly.

Installation

The thermal transfer material on the bottom of the heatsink is a phase change medium that is sandwiched to the FPGA surface and softens for conductivity under the heat and pressure of the clip.  To install, you should be able to hook one end of the clip on one of the anchors, then, while applying even pressure to the heatsink to make sure the FPGA itself has even pressure, hold that in place while you press the other end of the clip into the anchor.

Dimensions

Note that all dimensions are in (mm) with dimensions in inches in brackets.