Uwe, I think you are right. There is a SOT23 diode near the part that I thought was used for the voltage doubler but now I think it may be a reference. I just thought that since this is a new board that 2904 might mean the 29th week of '04. I am amazed this chip might have been produced in '94 as I know the PCB this was on was made this year. Thanks for all the input.
At 12:25 AM 9/2/2004 -0800, Uwe Zimmermann wrote:
I have to agree with Tony. 9420 is a typical date code (week 20 in 1994) while 2904 does not make sense as date code (week 4 in 1929 or 2029???). And a voltage regulator from two op-amps with some external reference (look for a zener diode) sounds reasonable.
If it is - as you say - a voltage doubler, the reference might just be gained by a 2:1 resistive voltage divider from the output, which is compared with the input voltage to give the error signal. It might as well be that the op-amp are just used to monitor the output current...
Uwe.
RR> Hi all, RR> I have a chip that has the ST logo on it and two numbers: RR> 2904 and 9420. Its an 8-pin SOIC package. I am assuming RR> the 2904 is the date code. I did a search on the ST site for RR> "9420" and came up empty. Does anyone have any idea RR> what this chip might be? RR> Thanks,
-Bob
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