The NI 9485 8-channel solid-state relay (SSR) digital output module is used on the National Instruments C Series platform. The NI 9485 is designed to operate at a temperature range of –40 to 70 °C. The specifications provided in the NI 9485 Operating Instructions are guaranteed across this full temperature range. However, when used at lower temperatures, the NI 9485 SSRs can operate at higher currents and/or faster switching speeds than indicated in the published specifications. This document provides information about the maximum allowable currents and switching rates across all operating temperatures.
Current Derating Curve
Figure 1 and Figure 2 display the maximum SSR switching characteristics based on channel count, ambient temperature, switching current, and switching rate. Refer to these graphs to determine the supported switching rate for your application.
Figure 1. Maximum Switching Characteristics (8 Channels Active)
Figure 2. Maximum Switching Characteristics (4 Channels Active)
For a scenario where the ambient temperature is 15 °C, switching 0.5 A on all 8 channels, what is the maximum switching rate? Using the 8-channel graph above, locate the 0.5 A current on the Y axis and trace it across the graph to the corresponding point on the 15 °C curve. From that point, trace down to the X axis and find the corresponding switching rate, which would be approximately 11 Hz.
If your application requires switching characteristics that fall outside of the parameters represented in these graphs, consider using the NI 9472 Sourcing Digital Output module for faster switching rates or NI 9481 EM Form A SPST Relay module for higher current. Related Links: NI 9485 Operating Instructions NI 9485 Product Page