1Publication Order Number:
1.5SMC6.8AT3/D
1.5SMC6.8AT3G Series,
SZ1.5SMC6.8AT3G Series
1500 Watt Peak Power
Zener Transient Voltage
Suppressors
Unidirectional*
The SMC series is designed to protect voltage sensitive
components from high voltage, high energy transients. They have
excellent clamping capability, high surge capability, low zener
impedance and fast response time. The SMC series is supplied in
the exclusive, cost-effective, highly reliable Littelfuse
package and is ideally suited for use in
communication systems, automotive, numerical controls, process
controls, medical equipment, business machines, power supplies and
many other industrial/consumer applications.
Specification Features
•Working Peak Reverse Voltage Range − 5.8 to 77.8 V
•Standard Zener Breakdown Voltage Range − 6.8 to 91 V
•Peak Power − 1500 W @ 1.0 ms
•ESD Rating of Class 3 (> 16 kV) per Human Body Model
•Maximum Clamp Voltage @ Peak Pulse Current
•Low Leakage < 5.0 mA Above 10 V
•UL 497B for Isolated Loop Circuit Protection
•Maximum Temperature Coefficient Specified
•Response Time is Typically < 1.0 ns
•SZ Prefix for Automotive and Other Applications Requiring Unique
Site and Control Change Requirements; AEC−Q101 Qualified and
PPAP Capable
•These are Pb−Free Devices are Available**
Mechanical Characteristics
CASE: Void-free, transfer-molded, thermosetting plastic
FINISH: All external surfaces are corrosion resistant and leads are
readily solderable
MAXIMUM CASE TEMPERATURE FOR SOLDERING PURPOSES:
260°C for 10 Seconds
LEADS: Modified L−Bend providing more contact area to bond pads
POLARITY: Cathode indicated by molded polarity bend
MOUNTING POSITION: Any
**Bidirectional devices will not be available in this series.
SURFACE MOUNT
ZENER OVERVOLTAGE
TRANSIENT SUPPRESSORS
5.8 − 78 VOLTS
1500 WATT PEAK POWER
Device*** Package Shipping
ORDERING INFORMATION
SMC
CASE 403
Cathode Anode
MARKING DIAGRAM
Littelfuse.com
Individual devices are listed on page 3 of this data sheet.
***The “T3” suffix refers to a 13 inch reel.
1.5SMCxxxAT3G SMC
(Pb−Free)
2,500 /
Tape & Reel
xxxA = Specific Device Code
(See Table on Page 3)
A = Assembly Location
Y = Year
WW = Work Week
G=Pb−Free Package
(Note: Microdot may be in either location)
SZ1.5SMCxxxAT3G SMC
(Pb−Free)
2,500 /
Tape & Reel
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
MAXIMUM RATINGS
Rating Symbol Value Unit
Peak Power Dissipation (Note 1) @ TL = 25°C, Pulse Width = 1 ms PPK 1500 W
DC Power Dissipation @ TL = 75°C
Measured Zero Lead Length (Note 2)
Derate Above 75°C
Thermal Resistance, Junction−to−Lead
PD
RqJL
4.0
54.6
18.3
W
mW/°C
°C/W
DC Power Dissipation (Note 3) @ TA = 25°C
Derate Above 25°C
Thermal Resistance from Junction−to−Ambient
PD
RqJA
0.75
6.1
165
W
mW/°C
°C/W
Forward Surge Current (Note 4) @ TA = 25°C IFSM 200 A
Operating and Storage Temperature Range TJ, Tstg −65 to +150 °C
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
1. 10 X 1000 ms, non−repetitive
2. 1 in. square copper pad, FR−4 board
3. FR−4 board, using Littelfuse minimum recommended footprint, as shown in 403 case outline dimensions spec.
4. 1/2 sine wave (or equivalent square wave), PW = 8.3 ms, duty cycle = 4 pulses per minute maximum.
ELECTRICAL CHARACTERISTICS (TA = 25°C unless
otherwise noted, VF = 3.5 V Max. @ IF (Note 5) = 100 A)
Symbol Parameter
IPP Maximum Reverse Peak Pulse Current
VCClamping Voltage @ IPP
VRWM Working Peak Reverse Voltage
IRMaximum Reverse Leakage Current @ VRWM
VBR Breakdown Voltage @ IT
ITTest Current
QVBR Maximum Temperature Coefficient of VBR
IFForward Current
VFForward Voltage @ IF
5. 1/2 sine wave or equivalent, PW = 8.3 ms non−repetitive duty
cycle
Uni−Directional TVS
IPP
IF
V
I
IR
IT
VRWM
VCVBR
VF
2Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
ELECTRICAL CHARACTERISTICS
Device*
Device
Marking
VRWM
(Note 6) IR @ VRWM
Breakdown Voltage VC @ IPP (Note 8)
QVBR
VBR V (Note 7) @ ITVCIPP
VmAMin Nom Max mA V A %/5C
1.5SMC6.8AT3G
1.5SMC7.5AT3G
1.5SMC8.2AT3G
6V8A
7V5A
8V2A
5.8
6.4
7.02
1000
500
200
6.45
7.13
7.79
6.8
7.5
8.2
7.14
7.88
8.61
10
10
10
10.5
11.3
12.1
143
132
124
0.057
0.061
0.065
1.5SMC10AT3G
1.5SMC12AT3G
1.5SMC13AT3G
10A
12A
13A
8.55
10.2
11.1
10
5
5
9.5
11.4
12.4
10
12
13
10.5
12.6
13.7
1
1
1
14.5
16.7
18.2
103
90
82
0.073
0.078
0.081
1.5SMC15AT3G
1.5SMC16AT3G
1.5SMC18AT3G
1.5SMC20AT3G
15A
16A
18A
20A
12.8
13.6
15.3
17.1
5
5
5
5
14.3
15.2
17.1
19
15
16
18
20
15.8
16.8
18.9
21
1
1
1
1
21.2
22.5
25.2
27.7
71
67
59.5
54
0.084
0.086
0.088
0.09
1.5SMC22AT3G
1.5SMC24AT3G
1.5SMC27AT3G
1.5SMC30AT3G
22A
24A
27A
30A
18.8
20.5
23.1
25.6
5
5
5
5
20.9
22.8
25.7
28.5
22
24
27
30
23.1
25.2
28.4
31.5
1
1
1
1
30.6
33.2
37.5
41.4
49
45
40
36
0.092
0.094
0.096
0.097
1.5SMC33AT3G
1.5SMC36AT3G
1.5SMC39AT3G
1.5SMC43AT3G
33A
36A
39A
43A
28.2
30.8
33.3
36.8
5
5
5
5
31.4
34.2
37.1
40.9
33
36
39
43
34.7
37.8
41
45.2
1
1
1
1
45.7
49.9
53.9
59.3
33
30
28
25.3
0.098
0.099
0.1
0.101
1.5SMC47AT3G
1.5SMC51AT3G
1.5SMC56AT3G
1.5SMC62AT3G
47A
51A
56A
62A
40.2
43.6
47.8
53
5
5
5
5
44.7
48.5
53.2
58.9
47
51
56
62
49.4
53.6
58.8
65.1
1
1
1
1
64.8
70.1
77
85
23.2
21.4
19.5
17.7
0.101
0.102
0.103
0.104
1.5SMC68AT3G
1.5SMC75AT3G
1.5SMC82AT3G
1.5SMC91AT3G
68A
75A
82A
91A
58.1
64.1
70.1
77.8
5
5
5
5
64.6
71.3
77.9
86.5
68
75
82
91
71.4
78.8
86.1
95.5
1
1
1
1
92
103
113
125
16.3
14.6
13.3
12
0.104
0.105
0.105
0.106
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
6. A transient suppressor is normally selected according to the working peak reverse voltage (VRWM), which should be equal to or greater than
the DC or continuous peak operating voltage level.
7. VBR measured at pulse test current IT at an ambient temperature of 25°C.
8. Surge current waveform per Figure 2 and derate per Figure 3 of the General Data − 1500 Watt at the beginning of this group.
* Include SZ-prefix devices where applicable.
3Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
NONREPETITIVE
PULSE WAVEFORM
SHOWN IN FIGURE 2
tP
, PULSE WIDTH
0.1
10
100
0.1 ms1 ms10 ms 100 ms1 ms 10 ms
Figure 1. Pulse Rating Curve
01234
0
50
100
t, TIME (ms)
VALUE (%)
HALF VALUE - IPP
2
PEAK VALUE - IPP
Figure 2. Pulse Waveform
Figure 3. Pulse Derating Curve
PEAK PULSE DERATING IN % OF
PEAK POWER OR CURRENT @ T
A= 25 C°
100
80
60
40
20
00 25 50 75 100 125 150
TA, AMBIENT TEMPERATURE (°C)
120
140
160
tP
PULSE WIDTH (tP) IS DEFINED
AS THAT POINT WHERE THE PEAK
CURRENT DECAYS TO 50%
OF IPP
.
DVBR, INSTANTANEOUS INCREASE IN VBR ABOVE VBR (NOM) (VOLTS)
0.3 0.5 0.7 1 2 3 5 7 10 20 30
1000
500
200
100
50
1
2
5
10
20
TL=25°C
tP=10ms
VBR(NOM)=6.8TO13V
20V
24V 43V
75V
120V
180V
Figure 4. Dynamic Impedance
Ppk, PEAK POWER (kW)
tr≤ 10 ms
IT
, TEST CURRENT (AMPS)
1
UL RECOGNITION
The entire series has Underwriters Laboratory
Recognition for the classification of protectors (QVGQ2)
under the UL standard for safety 497B and File .
Many competitors only have one or two devices recognized
or have recognition in a non-protective category. Some
competitors have no recognition at all. With the UL497B
recognition, our parts successfully passed several tests
including Strike Voltage Breakdown test, Endurance
Conditioning, Temperature test, Dielectric Voltage-Withstand
test, Discharge test and several more.
Whereas, some competitors have only passed a
flammability test for the package material, we have been
recognized for much more to be included in their Protector
category.
4Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
#E128662
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
APPLICATION NOTES
Response Time
In most applications, the transient suppressor device is
placed in parallel with the equipment or component to be
protected. In this situation, there is a time delay associated
with the capacitance of the device and an overshoot
condition associated with the inductance of the device and
the inductance of the connection method. The capacitive
effect is of minor importance in the parallel protection
scheme because it only produces a time delay in the
transition from the operating voltage to the clamp voltage as
shown in Figure 5.
The inductive effects in the device are due to actual
turn-on time (time required for the device to go from zero
current to full current) and lead inductance. This inductive
effect produces an overshoot in the voltage across the
equipment or component being protected as shown in
Figure 6. Minimizing this overshoot is very important in the
application, since the main purpose for adding a transient
suppressor is to clamp voltage spikes. The SMC series have
a very good response time, typically < 1.0 ns and negligible
inductance. However, external inductive effects could
produce unacceptable overshoot. Proper circuit layout,
minimum lead lengths and placing the suppressor device as
close as possible to the equipment or components to be
protected will minimize this overshoot.
Some input impedance represented by Zin is essential to
prevent overstress of the protection device. This impedance
should be as high as possible, without restricting the circuit
operation.
Duty Cycle Derating
The data of Figure 1 applies for non-repetitive conditions
and at a lead temperature of 25°C. If the duty cycle increases,
the peak power must be reduced as indicated by the curves
of Figure 7. Average power must be derated as the lead or
ambient temperature rises above 25°C. The average power
derating curve normally given on data sheets may be
normalized and used for this purpose.
At first glance the derating curves of Figure 7 appear to be
in error as the 10 ms pulse has a higher derating factor than
the 10 ms pulse. However, when the derating factor for a
given pulse of Figure 7 is multiplied by the peak power value
of Figure 1 for the same pulse, the results follow the
expected trend.
5Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
VL
V
Vin
Vin (TRANSIENT)
VL
td
V
Vin (TRANSIENT)
OVERSHOOT DUE TO
INDUCTIVE EFFECTS
tD = TIME DELAY DUE TO CAPACITIVE EFFECT
t t
Figure 5. Figure 6.
Figure 7. Typical Derating Factor for Duty Cycle
DERATING FACTOR
1 ms
10 ms
1
0.7
0.5
0.3
0.05
0.1
0.2
0.01
0.02
0.03
0.07
100 ms
0.1 0.2 0.5 2 5 10 501 20 100
D, DUTY CYCLE (%)
PULSE WIDTH
10 ms
TYPICAL PROTECTION CIRCUIT
Vin VL
Zin
LOAD
6Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
1.5SMC6.8AT3G Series, SZ1.5SMC6.8AT3G Series
PACKAGE DIMENSIONS
SMC
CASE 403−03
ISSUE E
DIM
A
MIN NOM MAX MIN
MILLIMETERS
1.90 2.13 2.41 0.075
INCHES
A1 0.05 0.10 0.15 0.002
b2.92 3.00 3.07 0.115
c0.15 0.23 0.30 0.006
D5.59 5.84 6.10 0.220
E6.60 6.86 7.11 0.260
L0.76 1.02 1.27 0.030
0.084 0.095
0.004 0.006
0.118 0.121
0.009 0.012
0.230 0.240
0.270 0.280
0.040 0.050
NOM MAX
7.75 7.94 8.13 0.305 0.313 0.320
HE
c
L1L A1
A
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. D DIMENSION SHALL BE MEASURED WITHIN DIMENSION P.
4. 403-01 THRU -02 OBSOLETE, NEW STANDARD 403-03.
0.020 REF
0.51 REF
L1
4.343
0.171
3.810
0.150
2.794
0.110 ǒmm
inchesǓ
SCALE 4:1
SOLDERING FOOTPRINT
Littelfuse.com
7Publication Order Number:
1.5SMC6.8AT3/D
Specifications subject to change without notice. © 2016 Littelfuse, Inc.
September 19, 2016 − Rev. 11
Information furnished is believed to be accurate and reliable. However, users should independently evaluate the suitability of and test each product
selected for their own applications. Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation,
military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other
application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those
expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any
purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products
used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products
is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse.
E
b D
HE