Hello. I'm interested in incorporating the CN0411 conductivity-measurement design into a circuit. (www.analog.com/.../cn0411.html)
I plan to use the analog components as listed, but with a different MCU and ADC.
1: In the flowchart that describes how to set the gain etc (Figure 12) What is V_DEF? Is it the 2.5V vref? The 0.4V default DAC output?
2: How long should the PWM 1 and 2 pulses be? (the ones that go in the middle of the V_EXC pulses. Is there a guide on configuring their on/off durations? The document provides the 2 standard frequences and a diagram (Figure 9). PWM0 is described as either 94Hz or 2.4kHz. (I assume that means cycle at these intervals), but I'm not clear on PWM 1 and 2.
3: Does this design supersede CN0349 and CN0359? The three documents don't mention each other. They were published in date that goes with their number, and all appear to accomplish the same task.
Thank you very much.