Arty S7 Rev C - Power Supplies

The Arty S7 board requires a 5 volt power source to operate. This power source can come from the Digilent USB-JTAG port (J10) or it can be derived from a 7 to 15 Volt DC power supply that’s connected to the Power Jack (J12) or Pin 8 of Header J7. Header JP13, labeled “5V SELECT”, is used to determine which source is used.

A power-good LED (LD9), driven by the “power good” (PWRGD) output of the ADP5052 regulator, indicates that the board is receiving power and that the onboard supplies are functioning as expected. If this LED does not illuminate when an acceptable power supply is connected and selected with JP13, please contact your distributor or Digilent Support for further help.

An overview of the Arty S7 power circuit is shown below.

Figure 1.1. Arty S7 power circuit. Figure 1.1. Arty S7 Power Circuit.

The USB port can deliver enough power for the vast majority of designs. However, a few demanding applications, including any that drive multiple peripheral boards, might require more power than the USB port can provide. Also, some applications may need to run without being connected to a PC’s USB port. In these instances an external power supply or battery pack can be used.

An external power supply can be used by plugging into Power Jack J12 and installing a jumper in the “REG” position on Header JP13. The supply must use a coaxial, center-positive 2.1mm (or 2.5mm) internal-diameter plug, and provide a voltage of 7 to 15 Volts DC. The supply should provide a minimum current of 1 amp. Ideally, the supply should be capable of providing 36 Watts of power (12 Volts DC, 3 amps).

An external battery pack can be used by connecting the battery's positive terminal to pin 8 of J7 (labeled VIN) and the negative terminal to pin 7 of J7 (labeled GND), as shown in Figure 1.2. In order to use the battery pack as the board’s power source a jumper must be installed in the “REG” position on Header J13. The battery must provide a voltage between 7 and 15 volts DC, and should NOT be installed while there is a supply connected to Power Jack J12.

Figure 1.2. Battery pack connection. Figure 1.2. Arty S7 Battery Pack Connection.

Voltage regulator circuits from Analog Devices and Texas Instruments create the required 3.3V, 1.8V, 1.35V, 1.25V, and 1.00V supplies from the 5V power source. In the event that an external supply or battery pack is used, the on-board Analog Devices 5V regulator provides the 5V source. Table 1.1 provides additional information (typical currents depend strongly on FPGA configuration and the values provided are typical of medium size/speed designs).

Supply Circuits Device Current (max/typical)
5V Onboard Regulators, RGB LEDs IC13: Analog Devices ADP2384 3.5A/0.375A to 2A
3.3V FPGA I/O, Clocks, Flash, PMODs, LEDs, Buttons, Switches, USB port IC12: Analog Devices ADP5052 2.2A/NA
1.00V FPGA Core and Block RAM IC12: Analog Devices ADP5052 1.0A/0.2A to 0.8A
1.8V FPGA Auxiliary IC12: Analog Devices ADP5052 1.0A/NA
1.35V DDR3L and associated FPGA bank IC12: Analog Devices ADP5052 1.0A/NA
1.25V XADC Analog Reference IC14: Texas Instruments REF3012 25mA/NA

Table 1.1. Arty S7 Power Rails.

Current Monitoring

The VCC1V0 (1.0V) and VCC1V8 (1.8V) rails each have a 0.010 Ohm current sense resistor for monitoring the amount of current being consumed by them. You can access them via JP3 for the VCC1V0 rail and JP4 for the VCC1V8 rail. To calculate the current on each power rail, use Ohm's law with R=0.010 and V equal to the measured voltage across the jumper. To measure the voltage you can use an external digital multimeter or oscilloscope.