HIP0081AS2 datasheet(10/14 Pages) INTERSIL

10 / 14 page

The Junction-to-Ambient equivalent to Equation 3, 3A is:

or:

Not all Integrated Circuit packages have a directly deﬁnable

case temperature because the heat is spread through the

lead frame to a PC Board which is the effective heat sink.

Calculation Example 1

For the HIP0081,

JC = 3

oC/W and the worst case junction

temperature, as an application design solution, should not

exceed 150oC. For a given application, Equation 1

determines the dissipation, PD.

Assume the package is mounted to a heat sink having a

thermal resistance of 6oC/W and, for a given application,

assume the dissipation is 3W and the ambient temperature

(TA) is 100

oC. From Equation 4, θJA is 9oC/W. The solution

for junction temperature (TC) by Equation 3 is:

TJ = 100

oC + 3W x 9oC/W = 127oC.

Calculation Example 2:

Assume for the HIP0080,

JA = 30

oC/W mounted on a PC

Board with good heat sinking characteristics. Again, the

worst case junction temperature, as an application design

solution, should not exceed 150oC. Assume from the

application, based on Equation 1, the dissipation,

PD = 1.5W. The maximum junction temperature is known

and can be used to determine the maximum allowable

ambient temperature from Equation 5A as follows:

TA = 150

oC - 1.5W x 30oC/W = 105oC.

Equal Current Loading Solution

Many applications may have equal current loading in the

output drivers with equal saturated turn ON and

temperature conditions. As such, a convenient method to

show rating boundaries is to substitute the dissipation

Equation 2 into the junction temperature Equation 3. For m

outputs that are ON and conducting with equal currents,

where I = I1=I2.....=Im, we have the following solution for

dissipation:

The number of output drivers ON and conducting (m) may

be from 1 to n. (i.e., For all four output drivers of the HIP0081

ON, m = 4.) Maximum temperature, dissipation and current

ratings must be observed. For a deﬁned number of

conducting Power MOS Output Drivers, we can plot the

results for m devices showing I vs TC.

Given the HIP0081 as an example, Figures 6 and Figure 7

illustrate the boundaries for temperature and current. Figure

6 shows the maximum current for a single output ON while

Figure 7 shows the maximum current for all four outputs ON

with equal current plotted versus Case Temperature, TC.

Boundary conditions relate to the Absolute Maximum

Ratings as deﬁned in the Data Sheet.

(EQ. 5)

(EQ. 5A)

–

(EQ. 6)

DS ON

()

–

DS ON

()

--------------------------------------------------

(EQ. 7)

FIGURE 6. HIP0081 MAXIMUM SINGLE OUTPUT CURRENT vs CASE (TAB) TEMPERATURE

100

125

150

0.0

0.5

1.0

1.5

2.0

2.5

3.0

CASE (HEAT SINK TAB) TEMPERATURE (oC)

(1)

(2)

CURVE (1): rDS(ON) = 1Ω

CURVE (2): rDS(ON) = 0.5Ω

THERMAL RESISTANCE,

θJC = 3oC/W

MAX. +IOUT(DC)

HIP0080, HIP0081

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