What is the purpose of burn-in circuits?

[Old Nick]

Burn-in circuits

Hi,

I'm intending to integrate a 85C54 or 85C55 chip into a system I'm designing. Towards the end of the data sheet, (link below) there are examples of burn in circuits, I am almost ashamed to say that I have no idea what the purpose of a burn in circuit is. Can anyone shed any light on the matter.
**broken link removed**

I've had a search around google and found many examples of burn-in circuits, but I've not found an explanation as to their purpose.

Cheers in advance.

Nick

 

[daviddlc]

Re: Burn-in circuits

If I remember correctly bur-in is to put a circuit in a temperature chamber with hot/cold cycles.

 

[Old Nick]

Re: Burn-in circuits

If I remember correctly bur-in is to put a circuit in a temperature chamber with hot/cold cycles.

Surely that would be quality control performed by the manufacturer, and the data sheet would have temperature guidelines for operation.
The circuits shown in the data sheet shows resistors tied to most of the pins, I assume that in a normal use, these resistors would not be present.
I'm sure there is a good reason why they've given these circuit diagrams instead of a 'typical application circuit', but I don't know why.

Cheers

 

[flatulent]

Re: Burn-in circuits

Burn in is a process done to qualify the design before the parts are mass produced. This is also used for reliability testing for specific applications like space satellites.

 

[Old Nick]

Re: Burn-in circuits

That's what I thought it was initially, but figured that (as I said earlier), this is something that the manufacturer uses and is of no real interest/relevance to an engineer, or am I missing something?

I would have thought a standard design guidlines would have been included before these circuits, but hey!

 

[JoeB01]

Re: Burn-in circuits

Notice that the burn-in circuits are specified for the 'MD' an 'MR' variants of the IC. These are ceramic hermetic packages and would be the packages used for military applications. MIL-STD-883 Method 1015 would normally govern a burn-in test. The burn-in test is a screening test (usually 168 Hours on every part) to eliminate marginal parts that may fail quickly. A similar test is the Life test that is used to characterize the part. The Life test is not a screening test, it is done on a batch basis. The burn-in circuits are of interest mostly to the manufacturer of the IC and possibly to military part specifiers.

 

[rikie_rizza]

Burn-in circuits

Nick,
They show you the burn-in circuit in the datasheet for your reference of application. So, if you use the device in such way that match the burn-in circuit, the device is guarantee to survive within its specified limit.
Burn-in is assembly related test to detect early failure of a device...burn-in result usually involved in the MTBF calculation.