PGA281: Front circuitry for PG281

shivakant dwivedi

Part Number: PGA281
Other Parts Discussed in Thread: ADS8688A, AMC1301, ISO124, PGA205, PGA203, PGA206

Hello,

I am using PGA281 for sensors data amplification.

There are various types of sensors.

Pressure sensors(Vout max 20 mVpp),Load cell(Vout max 20 mVpp),DC accelerometer(Vout max 2 Vpp) & Vibration sensors(Vout max 5 V).

Sensors Bw will be 5 KHz max.

Sensors output impedance will be less than 300 ohm.

I am using ADS8688A for data acquisitions from these sensors.

I need appropriate isolator at input side of signal conditioning befor PGA281. Please suggest??

For covering full dynamic range of ADC, i need higher gain so i am integrating this PGA281 with AD8421.

over 5 years ago

0 shivakant dwivedi over 5 years ago

Intellectual 960 points

This is the schematic i designed for signal conditioning of various sensors:

0 Alexander Davis over 5 years ago in reply to shivakant dwivedi

TI__Expert 6250 points

Hi Shivakant,
I'd consider AMC1301 for an isolator at the input of the PGA281.

0 shivakant dwivedi over 5 years ago in reply to Alexander Davis

Intellectual 960 points

Hello Mr. Davis,
Thanks for your response.
AMC1301 has max input range +-250 mV & our sensors output range is -20 mV to 5 V max.So i think i can't use this.
What about the ISO124??Can i use this at input of PGA281?
Did you see the schematic design which i sent you in previous queries?
Is there any other programmable gain amplifier which i can replace with PGA281 because it has 220 nV/root Hz noise at gain=1 .i our case , less than 10 nV/root Hz is acceptable over entire gain range.Please suggest appropriate.Because at this level of noise of PGA281,my SNR is degrading too much.

0 Alexander Davis over 5 years ago in reply to shivakant dwivedi

TI__Expert 6250 points

Hi Shivakant,

I don't think ISO124 will meet your specifications, as its input noise is 4uV/rtHz, and it has a ±50mV max offset spec - 2x your minimum input signal range.

The closest our PGAs get to a sub-10nV/rtHz noise level would be PGA203, PGA205, or PGA206. All of these are ~12nV/rtHz, but may not offer the gain range you require. Below that noise level, you may have to construct a discrete PGA using a low noise op amp and a low on-resistance switch.

0 Dennis Goeke over 5 years ago in reply to Alexander Davis

TI__Genius 11135 points

Shivakant

We haven't heard back from you so we assume this answered your questions. If you need additional help just post another reply below.

Thanks
Dennis

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PGA281: Front circuitry for PG281