Peak Current
It is the highest current a driver can carry only for a limited time, and it is always meaningful together with a duration figure. It covers short events such as starting, direction reversal and sudden loading. In the product data it is stated as a maximum value of 45 A for the KS250 and 40 A for the PT500.
What sets the limit is the thermal inertia of the power stage. The loss grows with the square of the current; three times the continuous rating means nine times the loss. The semiconductor can only accumulate that loss as far as its own thermal mass allows, after which the temperature protection steps in.
The correct way to read it:
- The peak value is given for a single event, not for repeated operation. An application that goes up to peak current several times a second is in practice considered to be running at the continuous current limit.
- The ratio between the peak and continuous values differs by model; the ratios in the product data apply as they are, so do not generalise by scaling between them yourself.
- An averaging multimeter is inadequate for the measurement; a current probe and an oscilloscope are needed to catch short pulses.
A soft start ramp is the most effective setting that directly reduces the peak current requirement, and in most cases it removes the need to move up to a higher model.
Context where this term is used: DC Motor Driver Selection Guide