DRV134 output tolerance

Sharwari Kulkarni15

Prodigy 30 points

Other Parts Discussed in Thread: DRV134

Hi,

I am using the DRV134 to output a 10VDC signal to power a strain gauge bridge.

The load can vary anywhere from 1.1K to higher. There is also a lowest value of 750ohm.

Looking at the performance curve on on page 6 , it looks like for a 10V output, the current can be max +/-40mA.

I am running simulations and observing that as I vary the load(1.1K ,750 ohms,5K,etc load).

I am observing that the output jumps around by almost 1V...even though I am not exceeding the output sourced current.

Am I missing something here?

I am attaching the schematic and simulation. I have to adjust R36 to get the output to be around 10VDC for a load value.

The output is fine with an open load.SG_schematic.pdf DC sweep_simulation.pdf

Thanks,

over 8 years ago

0 Ivan Salazar over 8 years ago

TI__Guru* 98235 points

Hi SK,

Welcome to E2E!
I'll take a look at this and come back to you asap.

Best regards,
-Ivan Salazar
Texas Instruments

0 Sharwari Kulkarni15 over 8 years ago in reply to Ivan Salazar

Prodigy 30 points

Hi,
Any update on this?

Thanks,
SK

0 Ivan Salazar over 8 years ago in reply to Sharwari Kulkarni15

TI__Guru* 98235 points

Hi SK,

Are you following one of the diagrams shown in the D/S?
A variation of output voltage should be expected when varying the load impedance for a wide range.

Best regards,
-Ivan Salazar
Texas Instruments

0 Sharwari Kulkarni15 over 8 years ago in reply to Ivan Salazar

Prodigy 30 points

Which curve to look at?

I am basically putting out DC voltage in the load....varying load from 750ohm to 1.5K.

What is the tolerance on the output variation?

Will u be able to take a look at the pdf's I posted? I am adding a resistance in the Vsense- Vo- pins to get the output voltage.

Is that correct?

Thanks,

0 Ivan Salazar over 8 years ago in reply to Sharwari Kulkarni15

TI__Guru* 98235 points

Hi SK,

Conventional transmission lines are 600 Ohm. The voltage variation is related to the load because of the current demand; lower loads demand higher current thus reduce the voltage, at higher loads the voltage increases. Unfortunately there is no data available on this respect.
Why are R34 and R35 20 Ohm? These seems to be too low. These balance resistors are shown in Figures 25 and 26 as 300 Ohm resistors. Perhaps increasing these resistors improve your voltage variation.

Best regards,
-Ivan Salazar
Texas Instruments

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DRV134 output tolerance