76105SK8 Просмотр технического описания (PDF) - Intersil
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76105SK8 Datasheet PDF : 12 Pages
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HUF76105SK8
Intersil provides thermal information to assist the designer’s
preliminary application evaluation. Figure 23 defines the RθJA
for the device as a function of the top copper (component side)
area. This is for a horizontally positioned FR-4 board with 1oz
copper after 1000 seconds of steady state power with no air
flow. This graph provides the necessary information for calcula-
tion of the steady state junction temperature or power dissipa-
tion. Pulse applications can be evaluated using the Intersil
device Spice thermal model or manually utilizing the normal-
ized maximum transient thermal impedance curve.
Displayed on the curve are RθJA values listed in the Electrical
Specifications table. The points were chosen to depict the
compromise between the copper board area, the thermal
resistance and ultimately the power dissipation, PDM.
Thermal resistances corresponding to other copper areas can
be obtained from Figure 23 or by calculation using Equation 2.
RθJA is defined as the natural log of the area times a coefficient
added to a constant. The area, in square inches is the top
copper area including the gate and source pads.
RθJA = 103.2 – 24.3 × ln (Area)
(EQ. 2)
The transient thermal impedance (ZθJA) is also effected by var-
ied top copper board area. Figure 24 shows the effect of copper
pad area on single pulse transient thermal impedance. Each
trace represents a copper pad area in square inches corre-
sponding to the descending list in the graph. SPICE and SABER
thermal models are provided for each of the listed pad areas.
Copper pad area has no perceivable effect on transient thermal
impedance for pulse widths less than 100ms. For pulse widths
less than 100ms the transient thermal impedance is deter-
mined by the die and package. Therefore, CTHERM1 through
CTHERM5 and RTHERM1 through RTHERM5 remain con-
stant for each of the thermal models. A listing of the model com-
ponent values is available in Table 1.
300
250
212 oC/W - 0.0115in2
200
175 oC/W - 0.054in2
150
100
50
RθJA = 103.2 - 24.3 * ln(AREA)
0
0.001
0.01
0.1
1
AREA, TOP COPPER AREA (in2)
FIGURE 23. THERMAL RESISTANCE vs MOUNTING PAD AREA
160
COPPER BOARD AREA - DESCENDING ORDER
0.020 in2
0.140 in2
120 0.257 in2
0.380 in2
0.493 in2
80
40
0
10-1
100
101
102
103
t, RECTANGULAR PULSE DURATION (s)
FIGURE 24. THERMAL IMPEDANCE vs MOUNTING PAD AREA
8-8
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