[SI-LIST] Re: Temperature Problem
- From: "Bashir, Shiraz (GE Healthcare)" <Shiraz.Bashir@xxxxxxxxxx>
- To: <prasadsa@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 28 Sep 2004 13:20:13 -0500
Hi Prasad,
a) What are the junction temperatures of major ICs such as CPU, Memory =
etc ?=20
You can get this info by looking at data sheet or asking manufacturer =
directly.
Is the main board in an Enclosure ? If yes then what are the ambient =
temperature inside the enclosure?
This might be cause as ICs are operated near their junction temperature =
they may stop functioning.=20
Don't confuse Commercial Grade Spec (0-70 degree C) of the IC with its =
junction temperature. IC is most probably at a higher junction =
temperature e.g., 100 degree C.
b) Typically in CPU based system, CPU 'halts', 'Resets', 'Hardware/ =
Software Watchdog kicks in". Do measurements at high temperature for =
these signals and see how they look like ? take these measurements at =
manageable temperature intervals e.g., room temp, room + 10, room + 20 =
etc.
c) If it resets (intermittently, recycle) then software may be "dumping" =
some error logs which you can examine and determine it is software reset =
or hardware.
d) Also measure Power Supply rails which are going to major ICs (CPU, =
Memory, Video ??). Are they within tolerance?
e) Other problems might be DFM related e.g., bad solder joints specially =
on BGA parts. Have board x-rayed ...
f) Also I have experience that use of mix metal Power Supply Connectors/ =
headers like tin on gold cause corrosion and may cause resets/ reboots.
g) Most probably your customer is doing thermal cycling for HALT- Highly =
Accelerated Life testing. Could you tell your customer to do same test =
under same conditions, software ver etc. on various boards. In HALT one =
should emphasize that problem is repeatable and reproducible.
I hope it helps.
regards,
shiraz bashir
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of saprasad
Sent: Tuesday, September 28, 2004 8:31 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Temperature Problem
Hi All,
Here is the details of problem we are facing:
We have developed the GP7000 Main Board V1.0 which is running at 258 =
MHz, while the version 1.2 developed at production site is running at =
250 MHz at normal temperature.
Client is testing the board at 65 deg chamber temperature. At this =
temperature the board stops working because the temperature at CPU will =
be near to 70 deg. Please note that the CPU and Memory are commercial =
grade. As per client's past experience, other products are running above =
70 deg temp at 200 MHz.=20
Is it possible to know what will happen to the CPU-Memory interface =
running at 250MHz at 70 deg ?=20
The failure is due to component operating temperature range or due to =
some synchronization loss between Memory and CPU?=20
What will be the behavior (impedance, rise time, fall time effect) of =
tracks at 70 deg ?
We have track length of 4 inch between CPU(S3C2410) and =
Memory(HY57V561620B). Whether this is playing any role at higher =
temperature?
Please advise us if you have any suggestions to sort out this problem.
Regards,
Prasad
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