Article ID: 000084395 Content Type: Product Information & Documentation Last Reviewed: 09/11/2012
How should unused REFCLKB, GXB_RX, and GXB_TX pins be connected in Stratix GX devices?
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Description It is recommended that the unused REFCLKB and unused transceiver pins be connected to GND or power supply as explained below to improve noise immunity. The positive arm of the differential pair should be connected via a 10k-. resistor to the GXB_VCC (1.5v). The negative arm of the differential pair should be connected via a 10k-. resistor to the GXB_GND. The .pin file generated by Quartus II software will reflect these recommendation from Quartus II v4.0 release on. Existing board laid-out without the REFCLKB and GXB pins tied off will suffer no adverse effect other than a slightly increased transceiver current. The increase current will be less than 5% of the operational current of the Quad.
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