HUFA75831SK8T FAIRCHILD [Fairchild Semiconductor], HUFA75831SK8T Datasheet - Page 6

• Manufacturer Part Number: HUFA75831SK8T
• Description: 3A, 150V, 0.095 Ohm, N-Channel, UltraFET Power MOSFET
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

Test Circuits and Waveforms
Thermal Resistance vs Mounting Pad Area
The maximum rated junction temperature, T
thermal resistance of the heat dissipating path determines the
maximum allowable device power dissipation, P
application. Therefore the application’s ambient temperature,
T
to ensure that T
mathematically represents the relationship and serves as the
basis for establishing the rating of the par t.
In using surface mount devices such as the SOP-8 package,
the environment in which it is applied will have a significant
influence on the part’s current and maximum power
©2001 Fairchild Semiconductor Corporation
P
A
DM
V
(
o
GS
C), and thermal resistance R
=
I
g(REF)
------------------------------ -
T
FIGURE 18. SWITCHING TIME TEST CIRCUIT
JM
FIGURE 16. GATE CHARGE TEST CIRCUIT
Z
JA
–
T
A
JM
V
GS
is never exceeded. Equation 1
R
GS
V
GS
JA
V
DS
(
o
C/W) must be reviewed
V
DUT
DS
R
JM
L
(Continued)
DUT
R
, and the
L
DM
, in an
-
+
V
DD
+
-
(EQ. 1)
V
DD
dissipation ratings. Precise determination of P
and influenced by many factors:
Fairchild provides thermal information to assist the
designer’s preliminary application evaluation. Figure 20
defines the R
I
V
g(REF)
1. Mounting pad area onto which the device is attached and
2. The number of copper layers and the thickness of the board.
3. The use of external heat sinks.
4. The use of thermal vias.
5. Air flow and board orientation.
6. For non steady state applications, the pulse width, the
0
0
DD
V
0
0
V
V
GS
whether there is copper on one side or both sides of the
board.
duty cycle and the transient thermal response of the part,
the board and the environment they are in.
DS
GS
10%
V
= 2V
GS
FIGURE 19. SWITCHING TIME WAVEFORM
FIGURE 17. GATE CHARGE WAVEFORMS
Q
t
d(ON)
90%
Q
gs
g(TH)
50%
t
JA
ON
10%
for the device as a function of the top
t
r
Q
PULSE WIDTH
Q
V
g(10)
DS
gd
Q
g(TOT)
V
GS
= 10V
t
d(OFF)
90%
HUFA75831SK8 Rev. B
t
DM
OFF
50%
t
is complex
f
10%
V
GS
90%
= 20V