E
AS
=
1
2
L × I
AS
2
where E
AS
= 300 mJ and I
AS
= 150 A, giving L = 0.0267 mH.
The temperature rise in the FET switch is given from the following equation:
ΔT
M
= F
2
× i 0
3
2
× L
1
2
where F
2
is a constant, and i(0) is the initial inductor current.
Use this equation once for the datasheet test case where I = 150 A and L = 0.0267 mH. Use
this equation again for the inductor and max current used on the actual load. By equating the
temperature rise for these two use cases, the constant F
2
cancels, and the maximum current for
a given load inductance can be determined using the following equation:
IL
MAX
= 150A ×
0.0267mH
LLoad
1
3
where L
LOAD
is in mH.
For example, IL
MAX
= 9.65 A with a 100 mH inductor. The FET switch will be damaged if
more than this current is actively interrupted while driving this inductor.
SLSC-12251 and SLSC-12252 User Manual
|
© National Instruments
|
15