Analog Devices AD5934 Product Info

• Programmable output peak-to-peak excitation voltage to a maximum frequency of 100 kHz
• Programmable frequency sweep capability with serial I²C interface 
• Frequency resolution of 27 bits (<0.1 Hz) 
• Impedance measurement range from 1 kΩ to 10 MΩ
• Capable of measuring 100 Ω to 1 kΩ with additional circuitry
• Phase measurement capability 
• System accuracy of 0.5% 
• 2.7 V to 5.5 V power supply operation
• Temperature range: −40°C to +125°C 
• 16-lead SSOP package

The AD5934 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 250 kSPS, analog-to-digital converter (ADC). The frequency generator allows an external complex impedance to be excited with a known frequency. The response signal from the impedance is sampled by the on-board ADC and a discrete Fourier transform (DFT) is processed by an on-board DSP engine. The DFT algorithm returns a real (R) and imaginary (I) data-word at each output frequency.

Once calibrated, the magnitude of the impedance and relative phase of the impedance at each frequency point along the sweep is easily calculated using the following two equations:

A similar device, available from Analog Devices, Inc., is the AD5933, which is a 2.7 V to 5.5 V, 1 MSPS, 12-bit impedance converter, with an internal temperature sensor, available in a 16-lead SSOP.

Applications

• Electrochemical analysis 
• Bioelectrical impedance analysis
• Impedance spectroscopy 
• Complex impedance measurement
• Corrosion monitoring and protection equipment
• Biomedical and automotive sensors
• Proximity sensing
• Nondestructive testing 
• Material property analysis 
• Fuel/battery cell condition monitoring