JAJSFS7B July 2018 – February 2019 LM5180-Q1
ADVANCE INFORMATION for pre-production products; subject to change without notice.
Set the turns ratio of the transformer secondary windings using Equation 29, where NS1 and NS2 are the number of secondary turns for the respective outputs.
Choose a primary-secondary turns ratio for the 15-V output based on an approximate 60% max duty cycle at minimum input voltage using Equation 30. The transformer turns ratio for both outputs is thus specified as 1 : 1 : 0.52.
Select a magnetizing inductance based on the minimum off-time constraint using Equation 31. Choose a value of 30 µH with a saturation current of 2 A for this application.