Need help finding replacement for obselete IC chip

[Guest]

I am working on a circuit that calls for a MM5837N noise generating IC chip.
This is an obselete chip and I need to find a chip that can take its place.

Any help in locating an alternate chip would be great.

 

[John Woodgate]

I read in sci.electronics.design that [email protected] wrote (in

I am working on a circuit that calls for a MM5837N noise generating IC chip.
This is an obselete chip and I need to find a chip that can take its place.

Any help in locating an alternate chip would be great.

You may not find a chip. There are many ways of generating noise. What
bandwidth do you want?

 

[Wim Ton]

I am working on a circuit that calls for a MM5837N noise generating IC
chip.

This is an obselete chip and I need to find a chip that can take its

place.

According to google, it still seems available form various sources.

An alternative may be to use an 8 pin uC like the ATTiny11 or a similar PIC.
The only change is that you have to insert it the wrong way round and patch
the Gnd to pin 8 (the MM5837N has an unusual pinout)

Wim

 

[Ed Price]

I am working on a circuit that calls for a MM5837N noise generating IC
chip.
This is an obselete chip and I need to find a chip that can take its
place.

Any help in locating an alternate chip would be great.

http://www.usbid.com show a supplier with 495 in stock.

There's a data sheet at:

http://www.alldatasheet.co.kr/datasheet-pdf/pdf_kor/NSC/MM5837N.html

And this engine shows two vendors in China with about 500 pieces:

http://www.hqew.com/en/buyer/invent...7N&sltType=IC&imageField.x=34&imageField.y=12

Try this too:

http://www.candisc.com/ranger/stock18.htm

Inland Empire, in Southern California, where I have bought some rare items a
few months ago, has about 100 pieces:

http://www.lookic.com/parts/?parts=MM5837N&B1=Request+a+Quote


Ed
wb6wsn

 

[Guest]

Thanks for the info.

 

[Clive Tobin]

A much better white noise source can be made with lots of stages of
jellybean shift register, with two taps XOR'd back to the data input,
with an external clock. The MM5837 is only 17 stages tapped at 14 so it
has an audibly repeating pattern.

The ARG (Audio Reference Generator) we used to make used 33 stages of
SR with taps at 20 and 33 fed back. This gives white noise that does
not audibly repeat (I forget the period, it was minutes or hours.) The
clock was I think about 100 kHz.

The noise generator in Dolby Stereo alignment equipment uses 49 stages
with taps at 44 and 49 fed back. With a 766 kHz clock, the repeat time
is 204,000 hours so you would be *very* hard pressed to hear a pattern.

I have often idly wondered how the designer comes up with the taps for
this service.

Cheers, Clive Tobin
www.tobincinemasystems.com

 

[Hal Murray]

I have often idly wondered how the designer comes up with the taps for

this service.

Mathematicians collect them.

There is a small table in Art of Electronics. Xilinx has a much
bigger table in one of their app-notes. Google for LFSR.

 

[Clive Tobin]

Found it! It is table 3 of
http://direct.xilinx.com/bvdocs/appnotes/xapp052.pdf covering all
combinations from 3 to 168 stages.

Thanks. Not that I'll ever know how they derive it, or need to use it
again...

 

[Richard Crowley]

I am working on a circuit that calls for a MM5837N noise generating IC
chip.
This is an obselete chip and I need to find a chip that can take its
place.

Any help in locating an alternate chip would be great.

Is there something so special that you MUST use an obsolete (and
likely ridiculously expensive) chip for such a generic function?

 

[Oppie]

I used a similar chip that was a bit more flexible, the AMI S2688. It had an
external clock option so I could shift the noise spectrum to my needs.
Device is also obsolete but was pin compatible with the 5837. I found 5 of
them in the back room if there is any interest. Finding a data sheet could
be a challenge though.
Plug-in solutions are great but if I had to do it again, would do it in a
PIC or AVR.
Oppie