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LPUF-10 Temperature Is High on the NE40E

Publication Date:  2013-09-03 Views:  49 Downloads:  0
Issue Description
After around an hour that LPUF-10 is inserted into the NE40E, an alarm indicating high temperature on LPUF-10 is generated on the NMS. Run the display temperature slot 7 command to check the temperature in slot 7 where LPUF-10 is located.
base-board, unit:c, slot7
pcb i2c addr chl status minor major fatal adj_speed temp
tmin tmax (c)
-----------------------------------------------------------------
lpuf 7 175 0 normal 65 75 81 55 65 61
lpuf 7 175 1 normal 90 96 102 80 90 52
lpuf 1 1 0 normal 70 80 90 60 70 49
lpuf 1 2 0 normal 60 70 80 50 60 58
lpuf 1 4 0 normal 70 80 90 60 70 48
lpuf 1 5 0 normal 80 90 100 70 80 61
lpuf 1 6 0 normal 70 80 90 60 70 46
lpuf 2 76 1 normal 90 96 102 80 90 73
lpuf 2 76 2 normal 90 96 102 80 90 71
tcmb 1 3 0 normal 70 80 90 60 70 50
tcmb 1 7 0 minor 60 70 80 50 60 60
e8gf 3 73 0 normal 80 86 100 80 100 39
e8gf 3 74 0 normal 80 86 100 80 100 40
e8gf 5 73 0 normal 80 86 100 80 100 38
e8gf 5 74 0 normal 80 86 100 80 100 39
e8gf 6 73 0 normal 80 86 100 80 100 40
e8gf 6 74 0 normal 80 86 100 80 100 39



An alarm is generated indicating that the LPU temperature exceeds the maximum value.
Handling Process
Tj indicates the junction temperature of the chip, which is the highest temperature of the actual semiconductor in an electronic device. In operation, the internal temperature of the chip is difficult to test, so the junction temperature is tested based on the case temperature. Tc indicates the case temperature. The formula for calculating Tj is as follows:
Tj = Tc + 11.6℃
The SM chip on LPUF-10 is developed by Huawei. Compared with other commercial chips, the SM chip adds two pins thermal_a and thermal_b that connect to sensors so that users can accurately read Tj and monitor the internal temperature of the SM chip. The read temperature is the junction temperature of the chip, and its value is higher than temperature in other nodes.
Root Cause
Some temperature monitoring nodes monitor the junction temperature that is higher than the temperature in other nodes.
Solution
Analyze the temperature of LPUF-10 based on the formula about Tj and Tc. The analysis result shows that the LPUF-10 temperature is within the normal range. Delete the alarms on the NMS.
Suggestions
Temperature monitoring pints of the LPUF-10, LPUF-21, and LPUF-40 contain two monitoring points that direct read the junction temperature of the chip, and the address is 76, so the temperature of address 76 monitoring point of the LPUF-21 and LPUF-40 is 12 higher than other monitoring points.

END