Switching regulators that rely on primary-side sensing in a flyback configuration are available as well. These devices use a closed loop architecture and eliminate the optocoupler by sensing the isolated output voltage indirectly based on the primary side flyback waveform. The flyback voltage is approximately equal to the sum of the output voltage and diode voltage times the primary to secondary turns ratio. Because the voltage at the output is not directly measured, any changes in the diode voltage vs. load current or temperature creates errors. These errors lead to higher variability in the performance of the isolated supply, especially load regulation and performance over temperature.