Date codes on chips 2000 to 2009

[n cook]

I recently repaired an amp with a manufacturing date on the plate on the
back of 2004.
The 4558 op-amp ICs inside had apparent datecodes of 4038.
Do some companies put 4038 instead of 0438 for 38th week of 2004 and same
for 2001 to 2009 ? , what about year 2000?

 

[Fred McKenzie]

I recently repaired an amp with a manufacturing date on the plate on the
back of 2004.
The 4558 op-amp ICs inside had apparent datecodes of 4038.
Do some companies put 4038 instead of 0438 for 38th week of 2004 and same
for 2001 to 2009 ? , what about year 2000?

NC-

I don't know the real answer, but they might be using a Julian date. Such
a date might look like 4038, refering to the 38th day of 2004 (or any year
ending in a 4).

I would expect a 38th week date format to be 0438 to distinguish it from
1994, et cetera. Similarly, the Julian version might be 04038. It would
not be unheard of for recently manufactured equipment to use components
made in 1994, especially if it is an older design.

Fred

 

[n cook]

NC-

I don't know the real answer, but they might be using a Julian date. Such
a date might look like 4038, refering to the 38th day of 2004 (or any year
ending in a 4).

I would expect a 38th week date format to be 0438 to distinguish it from
1994, et cetera. Similarly, the Julian version might be 04038. It would
not be unheard of for recently manufactured equipment to use components
made in 1994, especially if it is an older design.

Fred

4558s have been around a long time but I imagine the Just In Time /
accountancy wallahs would have something to say about componentry sitting on
shelves for a decade

 

[Bob Parker]

Can you tell us what brand the 4558s are? Often the manufacturers'
datasheets tell how to interpret the date codes.
I've recently bought SMD op-amps and DIP microcontroller chips with
'96' date codes, so they can sit around in storage for long periods.

Bob

 

[n cook]

Can you tell us what brand the 4558s are? Often the manufacturers'
datasheets tell how to interpret the date codes.
I've recently bought SMD op-amps and DIP microcontroller chips with
'96' date codes, so they can sit around in storage for long periods.

Bob

manufacturer
JRC

 

[Bob Parker]

As you no doubt discovered for yourself, there's little if anything
on the various websites for the Japan Radio Company which explains
their apparent IC date codes.
Not long ago I bought some 7662 negative supply generator chips
made by them (SMD package), and their 'date code' was '4021C'.

Bob