SNVA406C May   2010  – January 2022 LM27402

 

  1.   1
  2.   2
  3.   3
  4.   4
  5.   5
  6.   6
  7.   7
  8.   8
  9.   9
  10.   10
    1.     11
    2.     12
    3.     13
    4.     14
    5.     15
    6.     16
    7.     17
    8.     18
    9.     19
    10.     20
    11.     21
    12.     22
  11.   23
  12.   24
  13.   25

9.3 Inductor, Lout

As per data sheet recommendations, the inductor value should initially be chosen to produce a peak to peak ripple current between 20% and 40% of the maximum operating output current. A 30% current ripple was chosen for the LM27402 evaluation board. The minimum inductance required is calculated by:

Equation 6. GUID-FEC69856-1725-43E5-A900-97137D389DB6-low.gif

An actual inductor is selected based on a trade-off between physical size, efficiency, and current carrying capability. A Vishay IHLP5050 0.68-µH inductor results in a peak to peak current ripple of 6.4 A and offers a balance between efficiency (2.34-mΩ DCR), size (12.9 mm × 13.2 mm), and saturation current rating (49-A ISAT).