AD5933 Based PmodIA Impedance Analyzer
Created: Apr 06, 2016
No description available.
The 410-246 PmodIA impedance analyzer is a tool that can determine electrical impedance of a circuit. It is based on the AD5933 device, which offers a highly accurate system solution for impedance conversion. The tool is equipped with two SMA connectors where test probes that will be used in measuring electrical impedance can be attached. This impedance analyzer can measure impedances as low as 100Ω and as high as 10MΩ. The 410-246 PmodIA impedance analyzer can be accessed and programmed through its I2C communication bus.
In this design, the 410-246 PmodIA impedance analyzer communicates with the ATmega328P-PU microcontroller over the I2C bus. Before the tool can be used, it must be first calibrated to give a reliable reading. By using an external USB to serial converter, the tool can be calibrated through the ATmega328P-PU microcontroller. The calibration process includes entering the AD5933 into standby mode and setting its programmable gain amplifier (PGA) gain to 1. During the calibration, the excitation voltage and calibration frequency is set also. An impedance value for example 200kΩ must be placed between the two SMA connector during the calibration. Most of the calibration process is done through software. After calibrating the tool, it can now be used to measure unknown impedance at a known frequency. The measurement is sent to the ATmega328P-PU microcontroller and will be displayed on the LCD screen.
The impedance of a circuit varies with respect to the frequency it operates. The 410-246 PmodIA impedance analyzer allows setting up a frequency sweep easily. In this way, the impedance characteristics of a circuit can be found. Also, to perform any frequency sweep accurately, the SEL pin of the 410-246 PmodIA impedance analyzer must be connected to +5V or GND through SEL_Switch. The SEL_Switch connects the SEL pin to ground if it is closed. If it is opened, the SEL pin is connected to VCC through an on-board resistor. This SEL pin switches feedback resistors of an on-board op amp that is important in selecting or programming the peak-to-peak voltage of the output frequency in the sweep. For further information, please refer to the manual of the tool.