75631SK8 데이터 시트보기 (PDF) - Fairchild Semiconductor
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75631SK8 Datasheet PDF : 11 Pages
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HUFA75631SK8
Test Circuits and Waveforms (Continued)
VGS
Ig(REF)
VDS
RL
DUT
+
VDD
-
FIGURE 16. GATE CHARGE TEST CIRCUIT
VDD
VGS
VDS
Qg(TOT)
Qg(10)
VGS = 10V
VGS = 20V
VGS = 2V
0
Qg(TH)
Qgs
Ig(REF)
0
Qgd
FIGURE 17. GATE CHARGE WAVEFORMS
VDS
RL
VGS
RGS
DUT
+
VDD
-
VGS
FIGURE 18. SWITCHING TIME TEST CIRCUIT
Thermal Resistance vs. Mounting Pad Area
The maximum rated junction temperature, TJM, and the
thermal resistance of the heat dissipating path determines the
maximum allowable device power dissipation, PDM, in an
application. Therefore the application’s ambient temperature,
TA (oC), and thermal resistance RθJA (oC/W) must be reviewed
to ensure that TJM is never exceeded. Equation 1
mathematically represents the relationship and serves as the
basis for establishing the rating of the part.
PDM
=
(---T----J---M-------–----T----A-----)
ZθJA
(EQ. 1)
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
dissipation ratings. Precise determination of PDM is complex
and influenced by many factors:
©2001 Fairchild Semiconductor Corporation
VDS
tON
td(ON)
tr
90%
tOFF
td(OFF)
tf
90%
10%
0
10%
VGS
10%
0
50%
PULSE WIDTH
90%
50%
FIGURE 19. SWITCHING TIME WAVEFORM
1. Mounting pad area onto which the device is attached and
whether there is copper on one side or both sides of the
board.
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
duty cycle and the transient thermal response of the part,
the board and the environment they are in.
Fairchild provides thermal information to assist the
designer’s preliminary application evaluation. Figure 20
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 calculation of the steady state
HUFA75631SK8 Rev. B
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