Current Monitoring Application from Analog Devices in Multisim 12.0

[Mahmoud_W]

Hello Circuit Designers,

I've been recently looking into motor control designs, widely used in energy and automotive applications, and the reason for that is to learn more about how the new capability of accurate system simulation at desktop level using Multisim 12 and LabVIEW 2011 can be successfully implemented in this application area.

What caught my attention is the numerous pure analog circuits that are essential for these types of designs (motor control), apart from the main switching plant that requires digital logic/FPGA control. A good example is a high-precision current monitoring circuit. I came across this circuit that simplifies high side current monitoring by providing a high voltage interface and bidirectional current monitoring capability across a shunt resistor while using a single supply.

In no longer than half an hour, I was able to lay-down a schematic, simulate, and validate a design based on an Analog Devices circuit note and using their industry-standard SPICE models available in the Multisim's database for the following parts:

• AD8210:  High Voltage, Bidirectional Current Shunt Monitor.
• AD780:  2.5 V/3.0 V Ultrahigh Precision Bandgap Voltage Reference.
• AD8276:  Low Power, Wide Supply Range, Low Cost Unity-Gain Difference Amplifier.
  

The circuit schematic is shown in the following snippet (png image) which you can drag and drop directly into Multisim 12.0:

The following graphs show the transient response of the input load current and how the integrated current sensing device AD8210 responds and generates a proportional voltage that is level-shifted at the ouput stage of the AD8276.

Let me know your thoughts/feedback regarding this type of application.

Enjoy!

Mahmoud

National Instruments