PCM1861: signal conditioning block

Vincenzo Pizzolante

Part Number: PCM1861

hi,

we are using PCM1861 in a new audio system.

Our input source is (possibly) up to 26dBu (about 14Vpp) and we are looking for a suitable protection as the input max for the PCM is 2.1Vrms.

thansk a lot in advance

Vincenzo

over 5 years ago

0 Zak Kaye over 5 years ago

TI__Mastermind 23050 points

Hi Vincenzo,

We have a TI precision labs series on electrical overstress in data converters and how to protect the inputs that can be found here: https://training.ti.com/node/1139109?context=1139747-1128375-1139109. I hope that this is helpful! Please review and let me know if you have any questions.

Best,

Zak

0 Vincenzo Pizzolante over 5 years ago in reply to Zak Kaye

TI__Mastermind 25776 points

hi Zak,

it is not a perturbation, but an actual input signal level.

we are looking for an attenuation block (currently we have an idea with passive components, like in attachment).

filter.pdf

we simulated it and looks ok.

any active element to suggest?

thansk a lot in advance

Vincenzo

0 Zak Kaye over 5 years ago in reply to Vincenzo Pizzolante

TI__Mastermind 23050 points

Hi Vincenzo,

I'm not sure what the values of the bridge resistors are in your attached circuit but it looks to me like your intent is to clamp the input in the case where it reaches 14Vpp rather than attenuate the full range of the signal, is this correct? There are a few different ways you could approach this, I think you will find this other thread helpful: http://e2e.ti.com/support/audio/f/6/p/871436/3225850#3225850

If you do want 14Vpp to be a valid input and attenuate the full range you could do this passively, or you could use a fully-differential amplifier. This has the added benefit that the outputs of the amplifier can't exceed the supply voltage so it is inherently limiting. Here is an app note that discusses this implementation:

Best,

Zak

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PCM1861: signal conditioning block