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Field Notice: FN-63340 - WS-C2960S-48FPS-L, WS-C2960S-48FPD-L Power Supply Defect Business Unit: LSBU

Field Notice: FN-63340 - WS-C2960S-48FPS-L, WS-C2960S-48FPD-L Power Supply Defect Business Unit: LSBU

Revised July 30, 2010

July 21, 2010


NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

Revision History

Revision Date Comment
1.1
30-JUL-2010
Updated Title, Products Affected, and How To Identify Hardware Levels section
1.0
21-JUL-2010
Initial Public Release

Products Affected

Products Affected
WS-C2960S-48FPD-L
WS-C2960S-48FPS-L

Problem Description

The root cause has been identified as a defective linear regulator IC 803 impacting third party power supply vendor DC1021 and DC1022. The IC was purchased from the open market, not from a Semiconductor source, and does not perform to specification.

Background

The problem is related to the single IC that randomly shuts down. The IC is a linear regulator for secondary side micro. When the IC shuts down, the micro loses control of power enable, sync FET gate enable, parallel/current share signal, protection function and orderly sequence of power train shut down. In the case of two units in the system, when one unit loses control of the power train, the two units will not have correct voltage matching (current share signal cannot operate correctly). The unit will lower voltage set point and will sink current because output rectification uses sync FET. The sinking current or negative current will increase when FETs of both legs of transformers conduct together. When one set of FETs turns OFF, negative current in the inductor has no quick path to travel, and energy in the inductor will cause an avalanche of the FET. The avalanche energy significantly raises loss in sync FET which leads to destruction of the FET as seen in the failed units. In case of the single unit, the unit will shut down, albeit not in orderly manner. The unit is not likely to be damaged in this case because there is no external source to provide energy to build up heat in the FET.

Problem Symptoms

Power Supply Unit, have output reset (12 V toggle), A Green LED blinking. Then, after testing for a long time there will be no output voltage output and the Red LED (fail) turns on.

Workaround/Solution

Cisco is recommending to customers that are affected by this issue and can verify their Serial Number using the provided Serial Number tool to contact Cisco for replacement.

How to Identify Hardware Levels

Please use the link below to validate your serial number(s).

Cisco Serial Number Validation Tool

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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