LMP8640: Does LMP8640 can support Vs+=6V, Vs-=-6V application?

Zhizhao Niu

Part Number: LMP8640
Other Parts Discussed in Thread: INA281

Hi Team,

I found the pin name the LMP8640 Vs- is negative voltage pin. Does it can support apply +/-6V voltage on Vs+/Vs-? Thanks.

B.R.

Lucas

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 267950 points

A total supply voltage of 12 V is supported; see section 7.4 of the datasheet.

0 Zhizhao Niu over 1 year ago

TI__Intellectual 2675 points

Hi ladisch,

thanks. That means it can work with +/-6V, right? And how about INa281, I think InA281 can only support positive voltage.

br.

Lucas

0 Clemens Ladisch over 1 year ago in reply to Zhizhao Niu

Guru 267950 points

The INA281 supply supports up to 20 V. But if you want the INA281's GND to be your circuit's 0 V, then this will not work because its input cannot go more than 4 V below its GND.

0 Zhizhao Niu over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 2675 points

Hi Ladisch,

Sorry I didn't got your point. I means LMP8640 can support VS+=6V and Vs-=-6V application. But I think INA281 can not support this mode. It can only support Vs=6V, GND=0V application.

Thanks.

B.R.

Lucas

0 Zhizhao Niu over 1 year ago in reply to Zhizhao Niu

TI__Intellectual 2675 points

Let me specify my questions. I think INA281 Pin2 must connect to GND. Because it only support single supply range. But from LMP8640 datasheet, it seems LMP8640 Pin2 can support negative voltage. As long as Vs+-Vs-<12V. Such as Vs+=0V, Vs-=-12V is also supported. Am I right?

0 Clemens Ladisch over 1 year ago in reply to Zhizhao Niu

Guru 267950 points

Pin 2 if the INA281 is the reference for the output pin. So the question is what you are doing with the output.

If you want the output voltage to be referenced to 0 V, the you must connect pin 2 to 0 V, and this will not work because of the input limitation.
If the output voltage can be referenced to −6 V, then it will work.

0 Zhizhao Niu over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 2675 points

Hi Ladisch,

Sorry.... I don't understand... Could you please draw something or give more details? Thanks.

B.R.

Lucas

0 Clemens Ladisch over 1 year ago in reply to Zhizhao Niu

Guru 267950 points

What is the actual problem you're trying to solve? What will be done with the INA281's output signal?

+1 Guang Zhou over 1 year ago in reply to Clemens Ladisch

TI__Mastermind 29650 points

Hi Lucas,

Whether the pin is named Vs- or GND, its function is the same. GND is not necessarily 0V. You can connect it to any voltage of choice, what’s important is to make sure absolute max ratings are not violated. Further, system level voltage compliance is also observed.

For example, in the INA281 diagram, you could connect the the same power supplies as LMP8640. But you’ll need to check other pins and down-stream circuitry (system-level) for voltage compliance.

Regards, Guang

Amplifiers

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LMP8640: Does LMP8640 can support Vs+=6V, Vs-=-6V application?