D355B Datasheet, PDF (6/14 Pages) List of Unclassifed Manufacturers – Electroluminescent Lamp Driver IC

II. Inductor (L) Selection
The external inductor (L) selection for a D355B circuit greatly affects the output capability and current draw
of the driver. A careful designer will balance current draw considerations with output performance in the
choice of an ideal inductor for a particular application. Figures 3, 4, and 5 show typical brightness and
current draw of a D355B circuit with different inductor values, lamp sizes, and supply voltages while keeping
the LF constant. Please note that the DC resistance (DCR) of inductors with the same nominal inductance
value may vary with manufacturer and inductor type. Thus, inductors made by a different manufacturer
may yield different outputs, but the trend of the different curves should be similar. Lamp luminance is also
a function of lamp size. In each example, a larger lamp will have less luminance with approximately the
same current draw.
12
48
Brightness
10
Current
40
8
32
6
24
4
16
2
8
0
0
0
1
2
3
4
5
Inductor (mH)
Figure 3: V+ = 1.5V, 1 in² EL Lamp
12
10
8
6
4
2
0
0
Brightness
Current
1
2
3
4
Inductor (m H)
48
40
32
24
16
8
0
5
Figure 4: V+ = 3.0V, 1 in² EL Lamp
12
48
Brightness
10
Current
40
8
32
6
24
4
16
2
8
0
0
0
2
4
6
8
10
Inductor (mH)
Figure 5: V+ = 5.0V, 4 in² EL Lamp
7