User manual

25 GR-LEON4-ITX Development Board
User Manual
Power Supply and Voltage Regulation
The board operates from a single +5V DC power supply input. On board regulators generate
the following voltages:
• +3.3V for the GR-LEON4-ITX I/O voltage, interfaces and other peripherals
• +2.5V for LEON4 configuration voltage
• +1.8V for DDR2 supply voltage
• +1.2V for LEON4 Vcore voltage
As an alternative to the single +5V power supply input, an ATX style power connector is also
provided on the board, which may be more convenent if the board is to be installed in a Mini-
ITX style housing.
If PCI slots are to be used, then the ATX power connector should be used in order that
+3.3V, +5V, +12V and -12V will be correctly provided to the peripheral cards installed in the
slots.
Reset Circuit and Button
A standard Processor Power Supervisory circuit (TPS3705 or equivalent) is provided on the
Board to provide monitoring of the 3.3V power supply rail and to generate a clean reset
signal at power up of the Unit.
To provide a manual reset of the board, a miniature push button switch is provided on the
Main PCB for the control. Additionally connections are provided to an additional off-board
push-button RESET switch if this is required.
Watchdog
The LEON4 ASIC includes a Watchdog timer function which can be used for the purpose of
generating a system reset in the event of a software malfunction or crash.
On this development board the WDOGN signal is connected as shown in the Figure 2-20 to
© Aeroflex Gaisler AB August 2010, Rev. 0.3
Figure 2-19: Power Regulation Configuration
REGULATOR
+1.2V (Vcore)
EXTERNAL POWER
SUPPLY, REGULATED
+5V, >1A
J22 POWER
2.1mm JACK
REGULATOR
ATX POWER
CONN.
+3V3
+1.8V (Vddr2)
+2.5V (Vconfig)
+5V
PCI SLOTS
+3V3
PCI
+12V
-12V
J21