User Manual

22
Slew Rate Measurement and Actual Transition time
Current slew rate is defined as the change in current over time. A programmable slew rate
allows a controlled transition from one load setting to another. The actual transition time is
defined as the time for the input to change from 10% to 90%, or 90% to 10% of the
programmed current values. The graph below illustrates slew rate measurements.
Figure 14 - Slew Rate Measurement
Between the 10% and 90% region, the slew rate can be measured by observing the steepest
slope portion. In case of very large load changes, e.g. from no load to full load, the actual
transition time will be larger than the expected (measured) time. For this reason, the firmware
allows the user to program slew rate values outside of the specified slew rate ranges. The
minimum transition time for all programmable slew rates is also limited in cases where the
transition from one setting to another is very small, due to bandwidth limitations of the load.