PGA281: VSON - Negative voltage

siauhwa ong

Expert 1510 points

Part Number: PGA281

Hi,

Is it possible to use -2.5V for VSON and +2.5V for VSOP ?

And what is the consequenses for DVDD return voltage and digital control voltage ?

Thank you

over 8 years ago

0 Errol Leon6 over 8 years ago

TI__Expert 5850 points

Hello Siauhwa Ong,

I will need to check with one of the designers if this is possible and the effects on the digital control voltage are just the thresholds for digital high and low. I should have an answer for you in a couple of days.

Best regards,

Errol Leon
Texas Instruments
Precision Amplifier Application Engineer

0 siauhwa ong over 8 years ago in reply to Errol Leon6

Expert 1510 points

By the way, what kind biasing is suitable for single supply operation. For example : VSP= 18Vdc and VSN = 0/gnd.

Thank you

0 Errol Leon6 over 8 years ago in reply to Errol Leon6

TI__Expert 5850 points

Hello Siauhwa Ong,

I was able to verify with the designer where it looks that as long as the VSP is sufficiently higher you can run the DVDD higher than VSP. You should be able to use +/-2.5V.

Best regards,

Errol

0 Errol Leon6 over 8 years ago in reply to siauhwa ong

TI__Expert 5850 points

You will need to set the common-mode of the inputs to mid-supply. This can be achieved with a resistor at each input (IN+ and IN-) going to mid-supply.

Best regards,

Errol

0 siauhwa ong over 8 years ago in reply to Errol Leon6

Expert 1510 points

Hi Errol,

So, if I use 18 Vdc for Vsp and gnd (Vsn), the Vin + & Vin - should be connected to 9V..?

And what is the input range (as the second stage of pga281 is powered with VSOP of 5vdc)?

Thank you

0 Errol Leon6 over 8 years ago in reply to siauhwa ong

TI__Expert 5850 points

Hi Siauhwa,

That is correct. The input can be attenuated to be within the input range of the second stage.

Best,

Errol

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PGA281: VSON - Negative voltage