Another key feature of the closed loop Hall Effect current sensor is its ability to track or follow fast rising input current waveforms with minimal phase delay. The rate of change of current per unit time or di/dt of the typical input signals are on the order of µSeconds and the sensor must be able to measure in the same order of magnitude. The above example shows the input signal and the sensor output signal; the time between the point the input signal reaches 90% of its final value and the output reaches 90% of its final value is one way to measure response time. (Note: Tamura specifications define the response time to be 10% of input signal to 90% of output signal) No matter how response time is defined the Closed loop Hall Effect current sensors are able to respond to these high speed signals in less than 1µSec.