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AR# 34916

Virtex-6 RocketIO - How to connect unused Virtex-6 GTH pins

Description

How should I connect unused GTH pins?

Solution

Quads on the same side of the device share common power planes.

The following three cases are analyzed:

1) If all of the GTH Quads on the same side of the device are not used, then connect the pins as shown in the table below:

Pin Name Connection
MGTRXP[0:3]
MGTRXN[0:3]
VCCINT(1.0V)
MGTTXP[0:3]
MGTTXN[0:3]
VCCINT(1.0V)
MGTREFCLKP
MGTREFCLKN
VCCINT(1.0V)
MGTHAVCC VCCINT(1.0V)
MGTHAVCCRX VCCINT(1.0V)
MGTHAVCCPLL VCCINT(1.0V)
MGTHAVTT VCCINT(1.0V)
MGTRBIAS VCCINT(1.0V)

2) If any GTH Quads on the same side of the device are used, then all of the GTH power supply pins on that side of the part must be powered with nominal voltages.

The following table covers the case when a GTH Quad will not be used, but at least one other GTH Quad on that side of the part will be used:

Pin Name Connection
MGTRXP[0:3]
MGTRXN[0:3]
Float
MGTTXP[0:3]
MGTTXN[0:3]
Float
MGTREFCLKP
MGTREFCLKN
GND
MGTHAVCC 1.1 Vdc (See Note)
MGTHAVCCRX 1.1 Vdc (See Note)
MGTHAVCCPLL 1.8 Vdc (See Note)
MGTHAVTT 1.2 Vdc (See Note)
MGTRBIAS MGTHAVTT (1.2 Vdc)

3) In the partially used Quad for unused transmitters and receivers, connect the pins as shown in the table below:

Unused GTH - Pin Name Connection
MGTRXP[0:3]
MGTRXN[0:3]
Float
MGTTXP[0:3]
MGTTXN[0:3]
Float

Partially used Quad - Pin Name Connection
MGTHAVCC 1.1 Vdc
MGTHAVCCRX 1.1 Vdc
MGTHAVCCPLL 1.8 Vdc
MGTHAVTT 1.2 Vdc
MGTRBIAS Connect this pin to a 1K ohm resistor with the other terminal of the resistor connected to ground.
MGTHAGND GND

NOTE: GTH pins definition:

Pin Name Description
MGTRXP[0:3]
MGTRXN[0:3]
GTH receiver input pins.
MGTTXP[0:3]
MGTTXN[0:3]
GTH transmitter output pins.
MGTREFCLKP
MGTREFCLKN
GTH reference clock input pins.
MGTHAVCC Analog supply for internal circuits for the receiver and the transmitter. Nominal voltage = 1.1 Vdc
MGTHAVCCRX Analog supply for the PLL and the receiver equalizers. Nominal voltage = 1.1 Vdc
MGTHAVCCPLL Analog supply for the reference clock buffer and the PLL. Nominal voltage 1.8 Vdc
MGTHAVTT Analog supply for the transmit driver. Nominal voltage = 1.2 Vdc
MGTRBIAS Provides internal precision current, voltage and resistor references for the GTH QUAD. Connect this pin
to a 1K ohm resistor with the other terminal of the resistor connected to ground.
MGTHAGND Ground reference for the GTH transceiver internal circuitry. These pins should be connected to the printed circuit board power supply ground reference plane.

AR# 34916
Date Created 03/26/2010
Last Updated 02/11/2013
Status Active
Type General Article
Devices
  • Virtex-6 HXT