PGA300: aep transdcuers

fernando amatulli47

Part Number: PGA300
Other Parts Discussed in Thread: TL071

According to the data sheet he maximum current the PGA300 is able to deliver to the strain gauge sensor is 1.5mA.

This limit the minimum strain gauge output impadance to 800Ohm in case of power supply of 1.5V and 1700Ohm in case of power supply of 2.5V.

We normally use 500Ohm or 350Ohm strain gauges.

There is any trick I can adopt to use the PGA300?

over 7 years ago

0 Scott Cummins over 7 years ago

TI__Mastermind 31655 points

Hello,

For use with a low impedance bridge I would suggest designing a simple unity gain op-amp buffer from the VBRG supply. You can supply the opamp rail with the same supply as VPWR on the PGA300. The requirements for the op amp are not very strict. Even something as simple as the TL071 could be used.

Regards,

0 fernando amatulli47 over 7 years ago in reply to Scott Cummins

Prodigy 40 points

ok, thank you

0 fernando amatulli47 over 7 years ago in reply to fernando amatulli47

Prodigy 40 points

sorry I have a question.
If I use a gain op-amp buffer I will loose the ratiometric input?

0 Scott Cummins over 7 years ago in reply to fernando amatulli47

TI__Mastermind 31655 points

Hi Fernando,

The output can be set to ratiometric. The ratiometric output is independent of the input settings (aside from the VPWR of course). You can use a gain stage to increase the VBRG excitation voltage. However, keep in mind that the common mode voltage will also increase. The single-ended inputs of the VINPP and VINPN pins are limited to 1.8V max. You will have to ensure that the output of the bridge sensor does not exceed this. You can use a simple resistor divider to decrease the common mode voltage at the output of the bridge.

Regards,

0 fernando amatulli47 over 7 years ago in reply to Scott Cummins

Prodigy 40 points

of course. Thak you for your help

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PGA300: aep transdcuers