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AR# 34093 SP605 - Change to resistor network values on the MGT_AVcc rail

Description

A subset of SP605 boards exceed the Spartan-6 FPGA MGTAVCC voltage rail maximum by 0.18 V. The Spartan-6 FPGA Data Sheet (DS162) states that the Absolute Maximum Ratings for the MGTAVCC Analog supply voltage relative to GND is -0.5V min / 1.32V max. The excerpt from the Spartan-6 FPGA Data Sheet referenced below states that exceeding the MGTAVCC maximum voltage rating for extended periods of time might affect device reliability. Exposure to Absolute Maximum Ratings conditions for extended periods of time might affect device reliability.

References:

Solution

Change Captured in Schematics

Schematics have been updated with the correct resistor values. The version of schematic that captures this change is Rev 3. This is strictly a BOM change; a sub-set of Rev D Version 03 has the change. Further information is provided in the Traceability section below. The summary of the BOM change is as follows:
  • Changed R271 to 2.49K 1% Item 31
  • Changed R274 to 4.99K 1% Item 24

Traceability
To identify whether the board you have has the reworked resistors, flip the SP605 Rev D board over and look for the Assembly P/N code. ASSY P/N label of 0431534-03-xxx and earlier are affected by the MGTAVCC issue.
ASSY P/N label of 0431534-04-xxx and later are exempt of the MGTAVCC issue.

Article 34093

For prototyping designs with the GTP feature, the Rev D boards may need to be reworked. Below is the suggested procedure.

Next Steps

You may either contact Whizz Systems for rework service or you can choose to do the rework on your own.

Whizz Systems will provide the rework service for the S&H charges. Contact Whizz Systems at 408-980-0400 for more information. In order to rework the board on your own, follow the procedure out-lined below.

Procurement of Resistor Components

The resistors, listed above, are standard 0402, 1% tolerance and commonly available for purchase through many electronic component distributors throughout the world. The following is a www.DigiKey.com example. Any resistor manufacturer may be used provided they meet Description below.

Digikey Part Number: P2.49KLCT-ND

Manufacturer Part Number: ERJ-2RKF2491X

Description: RES 2.49K OHM 1/10W 1% 0402 SMD

Manufacturer: Panasonic ? ECG

Digikey Part Number: P4.99KLCT-ND

Manufacturer Part Number: ERJ-2RKF4991X

Description: RES 4.99K OHM 1/10W 1% 0402 SMD

Manufacturer: Panasonic ? ECG

Recommended Rework Procedure for affected boards

1. Replace Resistors

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2. Apply Board Power

3. Measure AVcc power rail

MGT_AVCC 1.2v
Measure at the center pin of J29 on the backside of the board GND on thick ring around center pin, or SMA Measured voltage must be between 1.14V and 1.26 V
Article 34093

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AR# 34093
Date Created 01/11/2010
Last Updated 10/28/2010
Status Active
Type
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