Hello guys,I want to design voltage-controlled current source for my current project. The currents should be in a range from 0 to 2.5mA. Load resistance should be up to 5Kohm. My idea was to use unity gain amplifier together with the buffer in the configuration like this: Voltage-dependent generated current can be expressed as
I = Vsine/R8;
You could check this article to help you in your design.
AD8276, a unity gain difference amplifier, is a good candidate for your design.
It costs a dollar on A grade, here is the product page on this…
Also, looking at the datasheet of LT6011 and LT1006, LT6011 input is limited to operate to V- + 1V while LT1006 input common mode include ground in single supply operation. Furthermore, please read page…
Based on the circuit on your first post, I think you are doing a low side sensing.
LT6081 has a good application circuit example on doing this on page 13 of its datasheet.
Also, looking at the datasheet of LT6011 and LT1006, LT6011 input is limited to operate to V- + 1V while LT1006 input common mode include ground in single supply operation. Furthermore, please read page 9 of LT1006 datasheet for details when operating the device on single supply.
Thank you so much! This is what I call a great support! Clear, fast and efficient!!!
I tried to follow the article and included AD8276 in my LTSpice simulations. I used Spice model of AD8276 from here in order to create LTSpice model of AD8276.
In my simulations, however, I did not achieve expected results. Neither the current is equal to Vref/R nor the generated current follows the shape of the Vref voltage (sine shape in my simulations):
Is there something wrong with AD8276 Spice model? In this thread from 2017, there were some issues with it.
Thanks once again for your time and effort!
Just to report you that I think I found the issue in my schematic. It seems I can't use AD8603 buffer because its supply voltage is up to 5.5V. With 5Kohm load resistance and 2.5mA load current, I go beyond 5.5V.
Consequently, the solution for the buffer is AD8661 or OP1177
Thanks once again for your great support!
One more thing... do you think there is a better way to monitor current through the load as well as voltage on load resistor?
The thread from 2017 on AD8276 spice model issue is about the noise model only.
LTC6081 is doing great job for me concernig current sensing. However, It is DUAL opamp in the package. Consequently, the chip is bigger, and I waste one opamp. Is there any equivalent of LTC6081 in the form of single opamp in the chip? This is the last thing I will bother you with in this thread!
Do you have a preferred package type?
LTC2050 or LTC2054 are related parts to LTC6081.
Both LTC2050/LTC2054 are great for me. SOT-23 package is also perfect for me!
Thanks, man! You've been of a great help to me! I am moving to PCB design now!