JAJSGH4A November 2018 – July 2019 LM25180-Q1
ADVANCE INFORMATION for pre-production products; subject to change without notice.
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Set the turns ratio of the transformer secondary windings using Equation 30, 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 31. 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 32. Choose a value of 30 µH with a saturation current of 2 A for this application.