Interesting new measurement chip-AD5933

[ashok]

Hi Guys,
I came across this interesting new chip that measures loudspeaker impedance , mag and phase . All functions are built into the chip.
Has anyone come across this one ?
I am not sure what the final application will be if incorporated into an audio amp (?). That is what the blurb seems to suggest.
Cheers.

http://www.analog.com/en/prod/0%2C28...5933%2C00.html

[sreten]

Applications
# Impedance Spectroscopy
# Electrochemical Analysis
# Battery Condition Monitoring
# Fuel Cell Condition Monitoring
# Non Destructive Testing
# Corrosion Analysis and Protection Equipment
# Bioelectrical Impedance Analysis
# Sensor and Biosensor Signal Processing
# Material Property Analysis

They don't mention anything about amplifiers, and I can see why.
The current state of the art DSP processing used in amplifiers
is massively advanced compared to this chips capabilities.

/sreten.

[ashok]

Hi Sreten,
That's a pretty interesting list.
Check out what I read about the chip at the following URL.

http://www.audiodesignline.com/showA...leID=186701266

However I don't quite get the need to measure speaker impedance by an amp to improve sound . Am I missing something here ?
Cheers.

[sreten]

Hi Ashok,

An amplifiers DSP could work out a loudspeakers impedance if it wanted to.
For example if it had a switched mode supply and wanted to set voltage.
Not that I'm saying any amplifiers do, they usually react to instantaneous current.
Which I suppose is pretty near instantantaneous impedance.

The article you refer to seems pretty ridiculous to me. First take
something that doesn't work below 1KHz, then bugger around
a lot with extra circuitry / techniques so it effectively works, all
to measure something of relatively limited practical value, and
if you did want to measure it a laptop with soundcard and a jig
is a far more sensible and user friendly proposition.

IMO a chip that doesn't work below 1kHz is not designed or
fit for purpose for any application related to loudspeakers.

/sreten.

[jackinnj]

The chip will work to very low frequency levels by using a lower frequency clock, which is pretty easy to do. It will also measure small impedance values with an additional opamp. The interface is I2C which isn't difficult to work with, and it gives both impedance and phase.

Standalone, you could use the AD5933 or AD5934 to measure the stability of an LDO power supply since you have both gain and impedance, and do this from 1kHz to 100kHz.