Hello,
I am looking at the datasheet for the AMC1304L05 isolated delta-sigma modulator (document SBAS655C).
Figure 51 in the datasheet shows an application of the AMC1304 in a three phase inverter to measure the current in the phases using current shunts. This is how I wish to use the device. I do not know what the DC link voltage and the PWM frequency are yet, but they could be 600V and 40KHz (guess).
The datasheet gives values for common mode transient immunity (CMTI), minimum 15kV/us, and Viorm, maximum working insulation voltage 1000V rms or 1500V DC.
Clearly I need to find a way to limit the rise and fall times of the phase voltages to no more than 15kV/us.
But what about the Viorm value. Is that 1000V rms at 50/60 Hz sinusoidal or is it independent of frequency and wave shape? (Does a different wave shape or high frequency cause more stress to the insulation?)
For the PWM inverter, the frequency will be, say, 40kHz and the wave shape will be rectangular (or rather trapezoidal if the rising and falling edges are limited to no more than 15kV/us).
Document slyy063, "High-voltage reinforced isolation: definitions and test methodologies" has a graph, figure 3, page 6, that shows a safe operating area (but for a ISO7842 part instead). The vertical axis slows lifetime.
With the voltage, frequency and wave shape described above (600V, 40kHz, square wave), where about would I be on the equivalent graph for the AMC1304? Would the part fail early because it is more stressed?
Robert Dinn