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Channel MOSFET. AN816 Datasheet |
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( DataSheet : www.DataSheet4U.com )
AN816
Vishay Siliconix
Dual-Channel LITTLE FOOTR 6-Pin SC-70 MOSFET
Copper Leadframe Version
Recommended Pad Pattern and Thermal Performance
Michael Speed
INTRODUCTION
The new dual 6-pin SC-70 package with a copper leadframe
enables improved on-resistance values and enhanced
thermal performance as compared to the existing 3-pin and
6-pin packages with Alloy 42 leadframes. These devices are
intended for small to medium load applications where a
miniaturized package is required. Devices in this package
come in a range of on-resistance values, in n-channel and
p-channel versions. This technical note discusses pin-outs,
package outlines, pad patterns, evaluation board layout, and
thermal performance for the dual-channel version.
PINĆOUT
Figure 1 shows the pin-out description and Pin 1 identification
for the dual-channel SC-70 device in the 6-pin configuration.
Both n-and p-channel devices are available in this package –
the drawing example below illustrates the p-channel device.
SOT-363
SC-70 (6-LEADS)
S1 1
6 D1
G1 2
5 G2
D2 3
4 S2
Top View
FIGURE 1.
PACKAGE DIMENSIONS
SCĆ70: 6ĆLEADS
654
123
eb
e1
D
E1 E
-B-
-A-
A2 A
A1
c
L
ECN: E-77648—Rev. A, New Issue
Dim
A
A1
A2
b
c
D
E
E1
e
e1
L
MILLIMETERS
Min Nom Max
0.90 – 1.10
– – 0.10
0.80 – 1.00
0.15 – 0.30
0.10
1.80
–
2.00
0.25
2.20
1.80
1.15
2.10
1.25
2.40
1.35
0.65BSC
1.20 1.30 1.40
0.10 0.20 0.30
7_Nom
INCHES
Min Nom Max
0.035 – 0.043
– – 0.004
0.031 – 0.039
0.006 – 0.012
0.004 – 0.010
0.071 0.079 0.087
0.071 0.063 0.094
0.045 0.049 0.063
0.026BSC
0.047 0.051 0.055
0.004 0.008 0.012
7_Nom
Document Number: 71405
15-Jan-01
www.DataSheet4U.com
www.vishay.com
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AN816
Vishay Siliconix
21 (mil)
65
71 (mil)
0,0 (mil)
12
26 (mil)
4 34 (mil)
3
FIGURE 2. Basic Footprints
28 (mil)
87 (mil)
654
105 (mil)
71 (mil)
27 (mil)
44 (mil)
61 (mil)
123
0.0 (mil)
17.5 (mil)
26 (mil)
21 (mil)
FIGURE 3. SC-70 (6 leads) Dual
BASIC PAD PATTERNS
The basic pad layout and dimensions for the 6-pin SC-70 are
shown in Figure 2. This pad pattern is sufficient for the
low-power applications for which this package is intended.
Increasing the drain pad pattern (Figure 3) yields a reduction
in thermal resistance and is a preferred footprint.
EVALUATION BOARD FOR THE DUALĆ
CHANNEL SC70Ć6
The 6-pin SC-70 evaluation board (EVB) measures 0.6 in. by
0.5 in. The copper pad traces are the same as in Figure 2. The
board allows for examination from the outer pins to the 6-pin
DIP connections, permitting test sockets to be used in
evaluation testing.
The thermal performance of the dual 6-pin SC-70 has been
measured on the EVB, comparing both the copper and Alloy
42 leadframes. This test was then repeated using the 1-inch2
PCB with dual-side copper coating.
A helpful way of displaying the thermal performance of the
6-pin SC-70 dual copper leadframe is to compare it to the
traditional Alloy 42 version.
Front of Board SC70-6
S1 D1
G1 G2
D2 S2
SC70–6 DUAL
www.vishay.com
2
Back of Board SC70-6
Document Number: 71405
15-Jan-01
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AN816
Vishay Siliconix
THERMAL PERFORMANCE
Junction-to-Foot Thermal Resistance
(the Package Performance)
Thermal performance for the dual SC-70 6-pin package is
measured as junction-to-foot thermal resistance, in which the
“foot” is the drain lead of the device as it connects with the
body. The junction-to-foot thermal resistance for this device is
typically 80_C/W, with a maximum thermal resistance of
approximately 100_C/W. This data compares favorably with
another compact, dual-channel package – the dual TSOP-6 –
which features a typical thermal resistance of 75_C/W and a
maximum of 90_C/W.
Power Dissipation
The typical RθJA for the dual-channel 6-pin SC-70 with a
copper leadframe is 224_C/W steady-state, compared to
413_C/W for the Alloy 42 version. All figures are based on the
1-inch2 FR4 test board. The following example shows how the
thermal resistance impacts power dissipation for the dual 6-pin
SC-70 package at varying ambient temperatures.
Alloy 42 Leadframe
Room Ambient 25_C
PD +
TJ(max) * TA
RqJA
PD +
150oC * 25oC
413oCńW
P + 303 mW
Elevated Ambient 60_C
PD +
TJ(max) * TA
RqJA
PD +
150oC * 60oC
413oCńW
P + 218 mW
Copper Leadframe
Room Ambient 25_C
PD +
TJ(max) * TA
RqJA
PD +
150oC * 25oC
224oCńW
P + 558 mW
Elevated Ambient 60_C
PD +
TJ(max) * TA
RqJA
PD +
150oC * 60oC
224oCńW
PD + 402 mW
Although they are intended for low-power applications,
devices in the 6-pin SC-70 dual-channel configuration will
handle power dissipation in excess of 0.5 W.
TESTING
To further aid the comparison of copper and Alloy 42
leadframes, Figures 5 and 6 illustrate the dual-channel 6-pin
SC-70 thermal performance on two different board sizes and
pad patterns. The measured steady-state values of RθJA for
the dual 6-pin SC-70 with varying leadframes are as follows:
LITTLE FOOT 6ĆPIN SCĆ70
1) Minimum recommended pad
pattern on the EVB board (see
Figure 4).
2) Industry standard 1-inch2 PCB
with maximum copper both sides.
Alloy 42
518_C/W
413_C/W
Copper
344_C/W
224_C/W
The results indicate that designers can reduce thermal
resistance (θJA) by 34% simply by using the copper leadframe
device as opposed to the Alloy 42 version. In this example, a
174_C/W reduction was achieved without an increase in board
area. If an increase in board size is feasible, a further 120_C/W
reduction can be obtained by utilizing a 1-inch2. PCB area.
The Dual copper leadframe versions have the following suffix:
Dual:
Compl.:
Si19xxEDH
Si15xxEDH
Document Number: 71405
15-Jan-01
www.vishay.com
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