AND8391-D Datasheet, PDF (4/8 Pages) ON Semiconductor – Thermal Considerations for the ON Semiconductor

AND8391/D
The curves of Figure 5 for the SOD−123 and Figure 6 for
the SOT−223 packages show the relationship between I_reg
and time. I_reg decreases with time due to the effect of power
on the die.
I_reg vs. TIME
37
32
36
T_A = 25°C
Vak = 7.5 V
31.5
35
31
34
T_A = 25°C
Vak = 7.5 V
33
30.5
32
30
31
30
29.5
29
0
5
10 15 20 25 30 35
TIME (s)
Figure 5. Typical SOD−123 30 mA, 300 mm²,
1 oz Cu, In Still Air
29
0
5
10 15 20 25 30 35
TIME (s)
Figure 6. Typical SOT−223 30 mA, 300 mm²,
2 oz Cu, In Still Air
Correlation studies show that for each package steady
state I_reg there is a corresponding Pulsed I_reg value. Notice
on these two−terminal devices that the SOT−223 I_reg(P) has
a lower value than the SOD−123 I_reg(P), which results in
I_reg(SS) of 30 mA. This is due to the better R_qJA of the
SOT−223. See Figures 7 and 8. The slope of the line in
Figures 7 and 8 will change if the actual footprint and board
thermal properties differ from the footprint listed in the
figures.
35
34
T_A = 25°C
Vak = 7.5 V
33
STEADY STATE CURRENT (I_reg(SS)) vs. Vak @ 30 mA
35
34
T_A = 25°C
Vak = 7.5 V
33
32
32
31
31
30
30
29
29
28
28
27
27
26
26
25
30 31 32 33 34 35 36 37 38 39 40 41 42 43
I_reg(P) (mA)
Figure 7. I_reg(SS) vs. I_reg(P) Testing SOD−123,
300 mm², 1 oz Cu, In Still Air
25
26 27 28 29 30 31 32 33 34 35 36 37
I_reg(P) (mA)
Figure 8. I_reg(SS) vs. I_reg(P) Testing SOT−223,
300 mm², 2 oz Cu, In Still Air
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