LMP91000 - Vref or Linear Regulator ?

juan camarasa

Intellectual 390 points

Other Parts Discussed in Thread: LMP91000, LM4120, LM385-ADJ

Hello I have the following question

Is possible to reduce the current consumption by changing Vref by Linear Regulator ?

http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=lmp91000&fileType=pdf

Voltage Reference input (pin 11)

Vref: http://www.ti.com/lit/ds/symlink/lm4120.pdf vref :2.5 (160 μA Typ)

Linear Regulator: http://www.ti.com/lit/ds/symlink/tps79718.pdf vout:1.8v (1.2μA typically)

The voltage is always greater than 3 volts than maintains the voltage at 1.8V in the linear regulator.
Is possible saving some current supply extending battery life ?

Thanks,

Juan

over 12 years ago

0 Tom Hendrick over 12 years ago

TI__Guru**** 171426 points

Hi Juan,

I don't believe that changing the reference source would have much of an impact on the current consumption of the LMP91000. I'll try to get you more detail shortly. In the meantime, what sampling rate are you using with the LMP91000? Are you trying to reduce reference current requirements of or overall current to the device?

0 Avi Chami1 over 12 years ago in reply to Tom Hendrick

Mastermind 7395 points

You can also check other references, there are many micropower references like the LM385-adj

0 Andreas Kraemer over 12 years ago

TI__Prodigy 725 points

Hi Juan,

looks you want to reduce the supply to the reference, not the LMP91000?

If yes, there are several possibilities:

Maybe you can use the reference of your ADC? If you have this available, it would be the best.

If you plan to use zero bias sensors, you can connect the internal reference directly to your supply voltage. There is an internal switch to do this. In this case you would need to monitor your supply, to know what your internal zero voltage is.

If all this does not work, you can also use low power references. Also a shunt reference (two pin, looks like a zener diode). These typically can work with very low currents.

Reducing the voltage at the reference pin would not help a lot. The refernce current will be proportional to the voltage, but it is VERY small.

Hope this helps?
Andreas

0 juan camarasa over 12 years ago in reply to Andreas Kraemer

Intellectual 390 points

Thank you very much for the replies, I'll do some testing and see what results I get.

Regards

Juan

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LMP91000 - Vref or Linear Regulator ?