Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

High side discharge current measurement from 1.2V battery needs many components?

Status
Not open for further replies.

Flyback

Well-Known Member
Hello,
The below circuit gives a positive output voltage which corresponds to the current in the sense resistor.
(i.e. output to the micro is referenced to ground even though 'vout' of LT1787 is referenced to -3V, because the opamp circuit has 'level-shifted' it)

-Is their a lower-component-count method of level shifting a voltage that's referenced to -3V, to being referenced at ground?


LT1787 CURRENT MONITOR DATASHEET:
https://cds.linear.com/docs/en/datasheet/1787fc.pdf

LTspice simulation and schematic attached
 

Attachments

  • LT1787 Level shifted Vout_1.pdf
    27.9 KB · Views: 185
  • LT1787 Level shifted Vout_1.txt
    9.7 KB · Views: 173
thanks
https://www.ti.com/lit/ds/symlink/ina282.pdf
..from the datasheet the INA282 appears superior to the LT1787 in many respects, and I thought Linear.com always were the last word in quality.

To do the job I want here with the INA282, it looks like all I would need would be a boost converter to provide the INA282's 2.7V minimum input voltage ("V+").

In other words, the INA282 is far more suitable than the LT1787?

I find it bizarre that INA282 seems to be able to have the sense voltage well outside of its supply rail.

Though on page 8 of the LT1787 datasheet they give great diagrams indicating the step response of LT1787. The INA282 datasheet does not appear to give this information...this current monitor will be used in a current regulator, so I need high bandwidth preferably.
 
Last edited:
You can do it with a op configured as a differential amplifier which is basically what that ic does.
An LMC series op amp chip can operate very close to the supply rail so you might not need a seperate power supply.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top