Fast Inductive Load Turn-off (Fast Demagnetization)

Traditionally, inductive loads (such as a solenoid drive) use a free-wheeling diode in parallel with the load to discharge stored energy to reach the Off status (zero current). This process is called Demagnetization.

PointMax standard output modules (5034-OB4, 5034-OB8, and 5034-OB16, plus 5034-UB8 and 5034-UB8F when configured with digital outputs) have the fast inductive load turn-off feature. If the inductive load is within the module's specified inductance and current rating, then no free-wheeling diode is required. Demagnetization is performed faster when compared to using an external free-wheeling diode. For the module inductance and current rating specifications, see the PointMax I/O System Specifications Technical Data, publication 5034-TD001.

There are two possible demagnetization scenarios. Typically, inductive load demagnetization happens as illustrated in Demagnetization Example 1. In this scenario, demagnetization happens entirely through the output and the output voltage is at a negative voltage of (SA voltage + VCL) during the demagnetization phase.

For 5034-UB8 and 5034-UB8F, in some situations, demagnetization happens as illustrated in Demagnetization Example 2. In this scenario, the demagnetization happens through the output. The output voltage switches between a negative voltage of (SA voltage + VCL) and approximately 0 volts during the demagnetization phase.