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Old 23rd November 2003, 02:18 PM   #1
paulb is offline paulb  Canada
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Default MPC50x analog mux for audio?

Has anybody looked at these as an alternative to relays or the Analog Devices muxes?
MPC507: 8-channel differential (or stereo)
MPC509: 4-channel differential

Pricing seems reasonable, about $8 CDN apiece.
http://www-s.ti.com/sc/ds/mpc507.pdf
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Old 24th November 2003, 12:07 AM   #2
paulb is offline paulb  Canada
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OK then, how about any standard analog muxes for audio use?
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Old 24th November 2003, 05:51 PM   #3
PRR is offline PRR  United States
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> MPC507: 8-channel differential

These are second-source for a very old Harris Gates part.

The series has been available for about 20 years, so it is probably not going to vanish soon.

These used to cost a heck of a lot more than $8, though I do recall them falling past $25 quite a few years ago.

Voltage handling is very good.

ON-resistance is very high. You need to consider this in all phases of design. The last time I considered them, the ON-resistance promised more noise than I could accept in a microphone preamp. It is not a big issue in line-level work. However the resistance variation with voltage, while small, is not clearly specified. You typicially need a LARGE swamping impedance to mask Ron variations and get low THD numbers.

In fact Ron for this heavily-protected part looks higher than I remember on the Harris parts.

Note this TI tip:

"Keep loading impedance as high as possible. This minimizes the resistive loading effects of the source resistance and multiplexer ON resistance. As a guideline, load impedance of 10^8Ω or greater will keep resistive loading errors to 0.002% or less for 1000Ω source impedances. A 10^6Ω load impedance will increase source loading error to 0.2% or more."

They want you to use 100MegΩ load! The error they are discussing isn't what we call distortion: THD will be lower than static DC error. But clearly you want at least 1 Meg.

Ah, TI has good Ron curves. Not very precise: drawn flat/level from -10V to +4.6V, but you can eyeball significant error above +5V. This may not be too important at line-level, and you may not need a super-high load impedance.
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Old 24th November 2003, 06:03 PM   #4
dhaen is offline dhaen  Europe
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Yes, I used them in production about 10 years ago. They sounded OK to me and many others. Since then I've "regressed" to relays. They're faultless by comparison, but have a finite lifespan.
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Old 24th November 2003, 06:44 PM   #5
paulb is offline paulb  Canada
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Thanks for the background. The datasheet does mention second-source, but a quick google didn't pin it on Harris.
I think NatSemi's audio handbook had a section on using analog muxes like the 40??, I'll check that out.

Paul
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Old 24th November 2003, 07:20 PM   #6
PRR is offline PRR  United States
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> quick google didn't pin it on Harris.

I don't know that Harris, or Gates, makes them any more.

I think Intersil got the government contract and the tooling.

The original part numbers start DG or ADG.

Google "509 multiplexer" got me these hits:

http://www.intersil.com/products/dev...o.asp?pn=DG409
http://www.intersil.com/products/dev....asp?pn=HI-509
http://www.intersil.com/data/fn/fn3142.pdf

http://www.xs4all.nl/~ganswijk/chipdir/f/mux.htm
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Old 27th November 2003, 06:09 PM   #7
rho is offline rho  Belgium
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I got some samples of the MAX397 (Maxim/Dallas Semiconductor). How do they compare to the MPC507? Thay are pin-compatible.
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Old 4th July 2004, 02:08 PM   #8
Johnix is offline Johnix  France
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Quote:
Originally posted by PRR
ON-resistance is very high. You need to consider this in all phases of design. The last time I considered them, the ON-resistance promised more noise than I could accept in a microphone preamp. It is not a big issue in line-level work. However the resistance variation with voltage, while small, is not clearly specified. You typicially need a LARGE swamping impedance to mask Ron variations and get low THD numbers.

Does this mean that you can't use them to source a power amp ?

Power amps have input impedance more or less around 50k

Having a 1k input source is still a problem ?
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Old 26th November 2004, 05:10 AM   #9
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I got some sample of the mpc507 and was wondering if someone could answer the last question posted

Thanx


Quote:
Originally posted by Johnix



Does this mean that you can't use them to source a power amp ?

Power amps have input impedance more or less around 50k

Having a 1k input source is still a problem ?
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Old 7th March 2005, 10:03 PM   #10
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So for multiple source/output switching is this a dead end then?
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