VISHAY SI7794DP

New Product
Si7794DP
Vishay Siliconix
N-Channel 30 V (D-S) MOSFET with Schottky Diode
FEATURES
PRODUCT SUMMARY
RDS(on) ()
ID (A)a
0.0034 at VGS = 10 V
60
0.0042 at VGS = 4.5 V
60
VDS (V)
30
Qg (Typ.)
23 nC
PowerPAK® SO-8
• Halogen-free According to IEC 61249-2-21
Definition
• SkyFET™ Monolithic TrenchFET® Gen III
Power MOSFET and Schottky Diode
• 100 % Rg Tested
• 100 % Avalanche Tested
• Compliant to RoHS Directive 2002/95/EC
APPLICATIONS
S
6.15 mm
5.15 mm
1
• Low Side in Vcore, System and Memory
- Notebook PCs
D
S
2
S
3
G
4
D
8
D
7
D
6
D
Schottky
Diode
G
5
N-Channel MOSFET
Bottom View
S
Ordering Information: Si7794DP-T1-GE3 (Lead (Pb)-free and Halogen-free)
ABSOLUTE MAXIMUM RATINGS (TA = 25 °C, unless otherwise noted)
Parameter
Drain-Source Voltage
Gate-Source Voltage
Continuous Drain Current (TJ = 150 °C)
Symbol
VDS
VGS
TC = 25 °C
TC = 70 °C
TA = 25 °C
TA = 70 °C
Limit
30
± 20
ID
Continuous Source-Drain Diode Current
TC = 25 °C
TA = 25 °C
IS
Single Pulse Avalanche Current
Single Pulse Avalanche Energy
L =0.1 mH
IAS
EAS
Maximum Power Dissipation
TC = 25 °C
TC = 70 °C
TA = 25 °C
TA = 70 °C
PD
TJ, Tstg
Operating Junction and Storage Temperature Range
V
60a
60a
28.6b, c
22.8b, c
80
IDM
Pulsed Drain Current (t = 300 µs)
Unit
60a
5.6b, c
40
80
48
31
mJ
5.0b, c
3.2b, c
- 55 to 150
Soldering Recommendations (Peak Temperature)d, e
A
260
W
°C
THERMAL RESISTANCE RATINGS
Parameter
Junction-to-Ambientb, f
Maximum
Maximum Junction-to-Case (Drain)
t  10 s
Steady State
Symbol
RthJA
RthJC
Typical
20
2.1
Maximum
25
2.6
Unit
°C/W
Notes:
a. Package limited.
b. Surface mounted on 1" x 1" FR4 board.
c. t = 10 s.
d. See solder profile (www.vishay.com/ppg?73257). The PowerPAK SO-8 is a leadless package. The end of the lead terminal is exposed copper
(not plated) as a result of the singulation process in manufacturing. A solder fillet at the exposed copper tip cannot be guaranteed and is not
required to ensure adequate bottom side solder interconnection.
e. Rework conditions: manual soldering with a soldering iron is not recommended for leadless components.
f. Maximum under steady state conditions is 70 °C/W.
Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
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This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
New Product
Si7794DP
Vishay Siliconix
SPECIFICATIONS (TJ = 25 °C, unless otherwise noted)
Parameter
Symbol
Test Conditions
Min.
VDS
VGS = 0, ID = 250 µA
30
VGS(th)
VDS = VGS, ID = 250 µA
1
IGSS
VDS = 0 V, VGS = ± 20 V
Typ.
Max.
Unit
Static
Drain-Source Breakdown Voltage
Gate-Source Threshold Voltage
Gate-Source Leakage
Zero Gate Voltage Drain Current
IDSS
On-State Drain Currenta
ID(on)
Drain-Source On-State Resistancea
Forward Transconductancea
RDS(on)
gfs
2.5
± 100
VDS = 30 V, VGS = 0 V
0.035
0.2
VDS = 30 V, VGS = 0 V, TJ = 100 °C
3
30
VDS 5 V, VGS = 10 V
30
V
nA
mA
A
VGS = 10 V, ID = 20 A
0.0027
0.0034
VGS = 4.5 V, ID = 10 A
0.0033
0.0042
VDS = 15 V, ID = 20 A
85

S
Dynamicb
Input Capacitance
Ciss
Output Capacitance
Coss
Reverse Transfer Capacitance
Crss
Total Gate Charge
Qg
Gate-Source Charge
Qgs
Gate-Drain Charge
Qgd
Rg
Gate Resistance
2520
VDS = 15 V, VGS = 0 V, f = 1 MHz
VDS = 15 V, VGS = 10 V, ID = 10 A
VDS = 15 V, VGS = 4.5 V, ID = 10 A
tr
Rise Time
td(off)
Turn-Off Delay Time
Fall Time
Turn-On Delay Time
f = 1 MHz
VDD = 15 V, RL = 1.5 
ID  10 A, VGEN = 4.5 V, Rg = 1 
0.3
1.1
2.2
22
40
16
30
55
10
20
td(on)
11
22
10
20
30
55
10
20
VDD = 15 V, RL = 1.5 
ID  10 A, VGEN = 10 V, Rg = 1 
tf
Fall Time
6.4
tf
td(off)
Turn-Off Delay Time
72
35
30
tr
Rise Time
48
23
nC
7.2
td(on)
Turn-On Delay Time
pF
630
220

ns
Drain-Source Body Diode Characteristics
Continuous Source-Drain Diode Current
a
IS
Pulse Diode Forward Current
ISM
Body Diode Voltage
VSD
Body Diode Reverse Recovery Time
trr
Body Diode Reverse Recovery Charge
Qrr
Reverse Recovery Fall Time
ta
Reverse Recovery Rise Time
tb
TC = 25 °C
60
80
IS = 3 A
IF = 10 A, dI/dt = 100 A/µs, TJ = 25 °C
A
0.39
0.5
V
28
55
ns
17
34
nC
14
14
ns
Notes:
a. Pulse test; pulse width  300 µs, duty cycle  2 %.
b. Guaranteed by design, not subject to production testing.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation
of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device reliability.
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Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
New Product
Si7794DP
Vishay Siliconix
TYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)
80
10
VGS = 10 V thru 3 V
8
ID - Drain Current (A)
ID - Drain Current (A)
64
48
32
16
6
TC = 25 °C
4
2
TC = 125 °C
0
0.0
0.5
1.0
1.5
2.0
0
2.5
0
0.8
1.6
2.4
3.2
VDS - Drain-to-Source Voltage (V)
VGS - Gate-to-Source Voltage (V)
Output Characteristics
Transfer Characteristics
0.0040
3200
0.0036
2560
4.0
Ciss
VGS = 4.5 V
C - Capacitance (pF)
RDS(on) - On-Resistance (Ω)
TC = - 55 °C
VGS = 2 V
0.0032
0.0028
VGS = 10 V
1920
1280
0.0024
Coss
640
0.0020
Crss
0
0
16
32
48
ID - Drain Current (A)
64
80
0
6
12
On-Resistance vs. Drain Current and Gate Voltage
24
30
Capacitance
10
1.8
RDS(on) - On-Resistance (Normalized)
ID = 10 A
VGS - Gate-to-Source Voltage (V)
18
VDS - Drain-to-Source Voltage (V)
8
6
VDS = 10 V
VDS = 20 V
4
VDS = 15 V
2
ID = 20 A
1.6
VGS = 10 V
1.4
VGS = 4.5 V
1.2
1.0
0.8
0.6
- 50
0
0
10
20
30
40
50
- 25
0
25
50
75
100
125
150
TJ - Junction Temperature (°C)
Qg - Total Gate Charge (nC)
Gate Charge
Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
On-Resistance vs. Junction Temperature
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This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
New Product
Si7794DP
Vishay Siliconix
TYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)
100
0.015
10
0.012
RDS(on) - On-Resistance (Ω)
IS - Source Current (A)
ID = 20 A
TJ = 150 °C
TJ = 25 °C
1
0.1
0.01
0.009
0.006
TJ = 125 °C
0.003
TJ = 25 °C
0.001
0.0
0.000
0.2
0.4
0.6
0.8
1.0
0
2
4
6
8
VGS - Gate-to-Source Voltage (V)
VSD - Source-to-Drain Voltage (V)
On-Resistance vs. Gate-to-Source Voltage
10-1
200
10-2
160
30 V
10-3
Power (W)
I R - Reverse (A)
Source-Drain Diode Forward Voltage
10 V
10-4
10
20 V
120
80
40
10-5
0
0.001
10-6
0
25
50
75
100
125
150
0.01
TJ - Temperature (°C)
Reverse Current (Schottky)
0.1
Time (s)
1
10
Single Pulse Power, Junction-to-Ambient
IDM Limited
100
ID Limited
ID - Drain Current (A)
10
1 ms
10 ms
Limited by RDS(on)*
1
100 ms
1s
10 s
0.1
TC = 25 °C
Single Pulse
DC
BVDSS Limited
0.01
0.01
0.1
1
10
100
VDS - Drain-to-Source Voltage (V)
* VGS > minimum VGS at which RDS(on) is specified
Safe Operating Area, Junction-to-Ambient
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Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
New Product
Si7794DP
Vishay Siliconix
TYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)
100
ID - Drain Current (A)
80
Package Limited
60
40
20
0
0
25
50
75
100
125
150
0
25
TC - Case Temperature (°C)
60
2.5
48
2.0
36
1.5
Power (W)
Power (W)
Current Derating*
24
1.0
0.5
12
0.0
0
0
25
50
75
100
TC - Case Temperature (°C)
Power, Junction-to-Case
125
150
50
75
100
125
TA - Ambient Temperature (°C)
150
Power, Junction-to-Ambient
* The power dissipation PD is based on TJ(max) = 150 °C, using junction-to-case thermal resistance, and is more useful in settling the upper
dissipation limit for cases where additional heatsinking is used. It is used to determine the current rating, when this rating falls below the package
limit.
Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
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This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
New Product
Si7794DP
Vishay Siliconix
TYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)
1
Normalized Effective Transient
Thermal Impedance
Duty Cycle = 0.5
0.2
Notes:
0.1
0.1
PDM
0.05
t1
t2
1. Duty Cycle, D =
t1
t2
2. Per Unit Base = RthJA = 70 °C/W
0.02
3. TJM - TA = PDMZthJA(t)
Single Pulse
4. Surface Mounted
0.01
0.0001
0.001
0.01
0.1
1
10
100
1000
Square Wave Pulse Duration (s)
Normalized Thermal Transient Impedance, Junction-to-Ambient
1
Normalized Effective Transient
Thermal Impedance
Duty Cycle = 0.5
0.2
0.1
0.1 0.05
0.02
Single Pulse
0.01
0.0001
0.001
0.01
Square Wave Pulse Duration (s)
0.1
1
Normalized Thermal Transient Impedance, Junction-to-Case
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon
Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and
reliability data, see www.vishay.com/ppg?67692.
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Document Number: 67692
S11-1150-Rev. A, 13-Jun-11
This datasheet is subject to change without notice.
THE PRODUCT DESCRIBED HEREIN AND THIS DATASHEET ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Package Information
Vishay Siliconix
PowerPAK® SO-8, (SINGLE/DUAL)
L
H
E2
K
E4
D
3
4
θ
4
b
3
2
D5
e
2
D1
D
2
1
D2
Z
0.150 ± 0.008
M
1
D4
θ
W
L1
E3
θ
A1
Backside View of Single Pad
H
K
E2
E4
L
1
D1
D5
2
3
D2
4
Notes
1. Inch will govern.
2 Dimensions exclusive of mold gate burrs.
3. Dimensions exclusive of mold flash and cutting burrs.
b
D2
Detail Z
K1
2
E1
E
D3(2x) D4
c
A
θ
E3
Backside View of Dual Pad
MILLIMETERS
INCHES
DIM.
MIN.
NOM.
MAX.
MIN.
NOM.
A
0.97
1.04
1.12
0.038
0.041
MAX.
0.044
A1
0.00
-
0.05
0.000
-
0.002
b
0.33
0.41
0.51
0.013
0.016
0.020
c
0.23
0.28
0.33
0.009
0.011
0.013
D
5.05
5.15
5.26
0.199
0.203
0.207
D1
4.80
4.90
5.00
0.189
0.193
0.197
D2
3.56
3.76
3.91
0.140
0.148
0.154
D3
1.32
1.50
1.68
0.052
0.059
0.066
D4
0.57 TYP.
D5
3.98 TYP.
0.0225 TYP.
0.157 TYP.
E
6.05
6.15
6.25
0.238
0.242
0.246
E1
5.79
5.89
5.99
0.228
0.232
0.236
E2
3.48
3.66
3.84
0.137
0.144
0.151
E3
3.68
3.78
3.91
0.145
0.149
0.154
0.75 TYP.
E4
0.030 TYP.
e
1.27 BSC
0.050 BSC
K
1.27 TYP.
0.050 TYP.
K1
0.56
-
-
0.022
-
-
H
0.51
0.61
0.71
0.020
0.024
0.028
L
0.51
0.61
0.71
0.020
0.024
0.028
L1
0.06
0.13
0.20
0.002
0.005
0.008
θ
0°
-
12°
0°
-
12°
W
0.15
0.25
0.36
0.006
0.010
0.014
M
0.125 TYP.
0.005 TYP.
ECN: T10-0055-Rev. J, 15-Feb-10
DWG: 5881
Document Number: 71655
Revison: 15-Feb-10
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AN821
Vishay Siliconix
PowerPAK® SO-8 Mounting and Thermal Considerations
Wharton McDaniel
MOSFETs for switching applications are now available
with die on resistances around 1 mΩ and with the
capability to handle 85 A. While these die capabilities
represent a major advance over what was available
just a few years ago, it is important for power MOSFET
packaging technology to keep pace. It should be obvious that degradation of a high performance die by the
package is undesirable. PowerPAK is a new package
technology that addresses these issues. In this application note, PowerPAK’s construction is described.
Following this mounting information is presented
including land patterns and soldering profiles for maximum reliability. Finally, thermal and electrical performance is discussed.
THE PowerPAK PACKAGE
The PowerPAK package was developed around the
SO-8 package (Figure 1). The PowerPAK SO-8 utilizes the same footprint and the same pin-outs as the
standard SO-8. This allows PowerPAK to be substituted directly for a standard SO-8 package. Being a
leadless package, PowerPAK SO-8 utilizes the entire
SO-8 footprint, freeing space normally occupied by the
leads, and thus allowing it to hold a larger die than a
standard SO-8. In fact, this larger die is slightly larger
than a full sized DPAK die. The bottom of the die attach
pad is exposed for the purpose of providing a direct,
low resistance thermal path to the substrate the device
is mounted on. Finally, the package height is lower
than the standard SO-8, making it an excellent choice
for applications with space constraints.
PowerPAK SO-8 SINGLE MOUNTING
The PowerPAK single is simple to use. The pin
arrangement (drain, source, gate pins) and the pin
dimensions are the same as standard SO-8 devices
(see Figure 2). Therefore, the PowerPAK connection
pads match directly to those of the SO-8. The only difference is the extended drain connection area. To take
immediate advantage of the PowerPAK SO-8 single
devices, they can be mounted to existing SO-8 land
patterns.
Standard SO-8
PowerPAK SO-8
Figure 2.
The minimum land pattern recommended to take full
advantage of the PowerPAK thermal performance see
Application Note 826, Recommended Minimum Pad
Patterns With Outline Drawing Access for Vishay Siliconix MOSFETs. Click on the PowerPAK SO-8 single
in the index of this document.
In this figure, the drain land pattern is given to make full
contact to the drain pad on the PowerPAK package.
This land pattern can be extended to the left, right, and
top of the drawn pattern. This extension will serve to
increase the heat dissipation by decreasing the thermal resistance from the foot of the PowerPAK to the
PC board and therefore to the ambient. Note that
increasing the drain land area beyond a certain point
will yield little decrease in foot-to-board and foot-toambient thermal resistance. Under specific conditions
of board configuration, copper weight and layer stack,
experiments have found that more than about 0.25 to
0.5 in2 of additional copper (in addition to the drain
land) will yield little improvement in thermal performance.
Figure 1. PowerPAK 1212 Devices
Document Number 71622
28-Feb-06
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1
AN821
Vishay Siliconix
PowerPAK SO-8 DUAL
The pin arrangement (drain, source, gate pins) and the
pin dimensions of the PowerPAK SO-8 dual are the
same as standard SO-8 dual devices. Therefore, the
PowerPAK device connection pads match directly to
those of the SO-8. As in the single-channel package,
the only exception is the extended drain connection
area. Manufacturers can likewise take immediate
advantage of the PowerPAK SO-8 dual devices by
mounting them to existing SO-8 dual land patterns.
For the lead (Pb)-free solder profile, see http://
www.vishay.com/doc?73257.
To take the advantage of the dual PowerPAK SO-8’s
thermal performance, the minimum recommended
land pattern can be found in Application Note 826,
Recommended Minimum Pad Patterns With Outline
Drawing Access for Vishay Siliconix MOSFETs. Click
on the PowerPAK 1212-8 dual in the index of this document.
The gap between the two drain pads is 24 mils. This
matches the spacing of the two drain pads on the PowerPAK SO-8 dual package.
REFLOW SOLDERING
Vishay Siliconix surface-mount packages meet solder
reflow reliability requirements. Devices are subjected
to solder reflow as a test preconditioning and are then
reliability-tested using temperature cycle, bias humidity, HAST, or pressure pot. The solder reflow temperature profile used, and the temperatures and time
duration, are shown in Figures 3 and 4.
Ramp-Up Rate
+ 6 °C /Second Maximum
Temperature at 155 ± 15 °C
120 Seconds Maximum
Temperature Above 180 °C
70 - 180 Seconds
Maximum Temperature
240 + 5/- 0 °C
Time at Maximum Temperature
20 - 40 Seconds
Ramp-Down Rate
+ 6 °C/Second Maximum
Figure 3. Solder Reflow Temperature Profile
10 s (max)
210 - 220 °C
3 °C(max)
4 °C/s (max)
183 °C
140 - 170 °C
50 s (max)
3 °C(max)
60 s (min)
Pre-Heating Zone
Reflow Zone
Maximum peak temperature at 240 °C is allowed.
Figure 3. Solder Reflow Temperatures and Time Durations
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Document Number 71622
28-Feb-06
AN821
Vishay Siliconix
THERMAL PERFORMANCE
Introduction
A basic measure of a device’s thermal performance is
the junction-to-case thermal resistance, Rθjc, or the
junction-to-foot thermal resistance, Rθjf. This parameter
is measured for the device mounted to an infinite heat
sink and is therefore a characterization of the device
only, in other words, independent of the properties of the
object to which the device is mounted. Table 1 shows a
comparison of the DPAK, PowerPAK SO-8, and standard SO-8. The PowerPAK has thermal performance
equivalent to the DPAK, while having an order of magnitude better thermal performance over the SO-8.
TABLE 1.
DPAK and PowerPAK SO-8
Equivalent Steady State Performance
Thermal
Resistance Rθjc
DPAK
PowerPAK
SO-8
Standard
SO-8
1.2 °C/W
1.0 °C/W
16 °C/W
Thermal Performance on Standard SO-8 Pad Pattern
Because of the common footprint, a PowerPAK SO-8
can be mounted on an existing standard SO-8 pad pattern. The question then arises as to the thermal performance of the PowerPAK device under these conditions.
A characterization was made comparing a standard SO-8
and a PowerPAK device on a board with a trough cut out
underneath the PowerPAK drain pad. This configuration
restricted the heat flow to the SO-8 land pads. The
results are shown in Figure 5.
Because of the presence of the trough, this result suggests a minimum performance improvement of 10 °C/W
by using a PowerPAK SO-8 in a standard SO-8 PC
board mount.
The only concern when mounting a PowerPAK on a
standard SO-8 pad pattern is that there should be no
traces running between the body of the MOSFET.
Where the standard SO-8 body is spaced away from the
pc board, allowing traces to run underneath, the PowerPAK sits directly on the pc board.
Thermal Performance - Spreading Copper
Designers may add additional copper, spreading copper, to the drain pad to aid in conducting heat from a
device. It is helpful to have some information about the
thermal performance for a given area of spreading copper.
Figure 6 shows the thermal resistance of a PowerPAK
SO-8 device mounted on a 2-in. 2-in., four-layer FR-4
PC board. The two internal layers and the backside layer
are solid copper. The internal layers were chosen as
solid copper to model the large power and ground
planes common in many applications. The top layer was
cut back to a smaller area and at each step junction-toambient thermal resistance measurements were taken.
The results indicate that an area above 0.3 to 0.4 square
inches of spreading copper gives no additional thermal
performance improvement. A subsequent experiment
was run where the copper on the back-side was
reduced, first to 50 % in stripes to mimic circuit traces,
and then totally removed. No significant effect was
observed.
Si4874DY vs. Si7446DP PPAK on a 4-Layer Board
SO-8 Pattern, Trough Under Drain
Rth vs. Spreading Copper
(0 %, 50 %, 100 % Back Copper)
60
56
Impedance (C/watts)
Impedance (C/watts)
50
40
Si4874DY
30
Si7446DP
20
51
46
100 %
41
10
0%
50 %
0
0.0001
0.01
1
100
10000
Pulse Duration (sec)
Figure 5. PowerPAK SO-8 and Standard SO-0 Land Pad Thermal Path
Document Number 71622
28-Feb-06
36
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
Figure 6. Spreading Copper Junction-to-Ambient Performance
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AN821
Vishay Siliconix
SYSTEM AND ELECTRICAL IMPACT OF
PowerPAK SO-8
In any design, one must take into account the change in
MOSFET rDS(on) with temperature (Figure 7).
On-Resistance vs. Junction Temperature
r DS(on) - On-Resistance ( )
(Normalized)
1.8
1.6
VGS = 10 V
ID = 23 A
Suppose each device is dissipating 2.7 W. Using the
junction-to-foot thermal resistance characteristics of the
PowerPAK SO-8 and the standard SO-8, the die temperature is determined to be 107 °C for the PowerPAK
(and for DPAK) and 148 °C for the standard SO-8. This
is a 2 °C rise above the board temperature for the PowerPAK and a 43 °C rise for the standard SO-8. Referring
to Figure 7, a 2 °C difference has minimal effect on
rDS(on) whereas a 43C difference has a significant effect
on rDS(on).
Minimizing the thermal rise above the board temperature by using PowerPAK has not only eased the thermal
design but it has allowed the device to run cooler, keep
rDS(on) low, and permits the device to handle more current than the same MOSFET die in the standard SO-8
package.
1.4
1.2
1.0
0.8
0.6
- 50
- 25
0
25
50
75
100
125
150
TJ - Junction Temperature (°C)
Figure 7. MOSFET rDS(on) vs. Temperature
A MOSFET generates internal heat due to the current
passing through the channel. This self-heating raises
the junction temperature of the device above that of the
PC board to which it is mounted, causing increased
power dissipation in the device. A major source of this
problem lies in the large values of the junction-to-foot
thermal resistance of the SO-8 package.
PowerPAK SO-8 minimizes the junction-to-board thermal resistance to where the MOSFET die temperature is
very close to the temperature of the PC board. Consider
two devices mounted on a PC board heated to 105 °C
by other components on the board (Figure 8).
PowerPAK SO-8
Standard SO-8
107 °C
0.8 °C/W
148 °C
CONCLUSIONS
PowerPAK SO-8 has been shown to have the same
thermal performance as the DPAK package while having the same footprint as the standard SO-8 package.
The PowerPAK SO-8 can hold larger die approximately
equal in size to the maximum that the DPAK can accommodate implying no sacrifice in performance because of
package limitations.
Recommended PowerPAK SO-8 land patterns are provided to aid in PC board layout for designs using this
new package.
Thermal considerations have indicated that significant
advantages can be gained by using PowerPAK SO-8
devices in designs where the PC board was laid out for
the standard SO-8. Applications experimental data gave
thermal performance data showing minimum and typical
thermal performance in a SO-8 environment, plus information on the optimum thermal performance obtainable
including spreading copper. This further emphasized the
DPAK equivalency.
PowerPAK SO-8 therefore has the desired small size
characteristics of the SO-8 combined with the attractive
thermal characteristics of the DPAK package.
16 C/W
PC Board at 105 °C
Figure 8. Temperature of Devices on a PC Board
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4
Document Number 71622
28-Feb-06
Application Note 826
Vishay Siliconix
RECOMMENDED MINIMUM PADS FOR PowerPAK® SO-8 Single
0.260
(6.61)
0.150
(3.81)
0.050
0.174
(4.42)
0.154
(1.27)
0.026
(0.66)
(3.91)
0.024
(0.61)
0.050
0.032
0.040
(1.27)
(0.82)
(1.02)
Recommended Minimum Pads
Dimensions in Inches/(mm)
Return to Index
Return to Index
APPLICATION NOTE
Document Number: 72599
Revision: 21-Jan-08
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15
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