ZHCSPB0 april 2023 LM5171-Q1
ADVANCE INFORMATION
For best current monitor accuracy, choose IMONx resistor that the maximum operating voltage on the IMONx pin is less than 3 V.
Considering two phase current monitoring with maximum 50A for each channel, and make sure IMONx voltage no more than 3V, RIMONx can be find as:
Choose CIMONx considering delay and voltage ripple. Here we select:
Then the delay of the monitor is determined by the following time constant:
At full load, the DC component of the monitor voltage is:
Considering the inductor ripple current, according to Equation 6, the IOUT peak to peak ripple current is:
The RC filter corner frequency is thus given by:
The resulting peak-to-peak monitor ripple voltage is approximately determined by:
The peak-to-peak monitor ripple voltage is approximately 0.34% of the full load DC monitor voltage. Increasing CIMONx attenuates the ripple voltage at the cost of higher monitor delay.