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3.3 Volt TVS Array For ESD and Latch-Up Protection
PROTECTION PRODUCTS Description
The SMF series of TVS arrays are designed to protect sensitive electronics from damage or latch-up due to ESD, lightning, and other voltage-induced transient events. Each device will protect up to four lines operating at 3.3 volts. The SMF3.3 is a solid-state devices designed specifically for transient suppression. It is constructed using Semtech's proprietary EPD process technology. The EPD process provides low standoff voltages with significant reductions in leakage currents and capacitance over traditional pn junction processes. They offer desirable characteristics for board level protection including fast response time, low clamping voltage and no device degradation. The SMF3.3 may be used to meet the immunity requirements of IEC 61000-4-2, level 4 (15kV air, 8kV contact discharge). The small SC70-5L package makes them ideal for use in portable electronics such as cell phones, PDAs, and notebook computers.
SMF3.3
Features
ESD protection for data lines to IEC 61000-4-2 (ESD) 15kV (air), 8kV (contact) IEC 61000-4-4 (EFT) 40A (5/50ns) Small package for use in portable electronics Protects four I/O lines Working voltage: 3.3V Low leakage current Low operating and clamping voltages Solid-state EPD TVS technology
Mechanical Characteristics
EIAJ SC70-5L package Molding compound flammability rating: UL 94V-0 Marking : Marking Code Packaging : Tape and Reel
Applications
Cellular Handsets and Accessories Cordless Phones Personal Digital Assistants (PDAs) Notebooks and Handhelds Portable Instrumentation Digital Cameras Peripherals MP3 Players
Circuit Diagram
1 3 4 5
Schematic & PIN Configuration
1 2 3
5
4
2
SC70-5L (Top View)
Revision 01/15/08 1 www.semtech.com
SMF3.3
PROTECTION PRODUCTS Absolute Maximum Rating
R ating Peak Pulse Power (tp = 8/20s) Peak Pulse Current (tp = 8/20s) ESD per IEC 61000-4-2 (Air) ESD per IEC 61000-4-2 (Contact) Lead Soldering Temperature Operating Temperature Storage Temperature Symbol Pp k IP P VESD TL TJ TSTG Value 40 5 20 15 260 (10 seconds) -55 to +125 -55 to +150 Units Watts A kV
o
C C C
o
o
Electrical Characteristics
SMF3.3 Parameter Reverse Stand-Off Voltage Punch-Through Voltage Snap -Back Voltage Reverse Leakage Current Clamp ing Voltage Clamp ing Voltage Steering Diode Forward Voltage Junction Cap acitance Symbol VRWM V PT VSB IR VC VC VF Cj IPT = 2A ISB = 50mA VRWM = 3.3V IPP = 1A, tp = 8/20s IPP = 5A, tp = 8/20s IPP = 1A, tp = 8/20s Ground to any I/O Each I/O p in and Ground VR = 0V, f = 1MHz I/O to I/O VR = 0V, f = 1MHz 25 3.5 2.8 0.05 0.5 5.5 8.0 2.4 30 Conditions Minimum Typical Maximum 3.3 Units V V V A V V V pF
12
pF
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SMF3.3
PROTECTION PRODUCTS Typical Characteristics
Non-Repetitive Peak Pulse Power vs. Pulse Time
1
110 100 90 % of Rated Power or I PP 80 70 60 50 40 30 20 10 0 0 25 50 75 100 125 150
Power Derating Curve
Peak Pulse Power - P PP (kW)
0.1
0.01 0.1 1 10 Pulse Duration - tp (s) 100 1000
Ambient Temperature - TA (oC)
Pulse Waveform
110 100 90 80 Percent of IPP 70 60 50 40 30 20 10 0 0 5 10 15 Time (s) 20 25 30 td = IPP/2 e-t Waveform Parameters: tr = 8s td = 20s
Clamping Voltage vs. Peak Pulse Current
10.00
8.00 Clamping Voltage - V (V) C
6.00
4.00
2.00
Waveform Parameters: tr = 8s td = 20s
0.00 0 1 2 3 4 5 6 7 Peak Pulse Current - IPP (A)
Forward Voltage vs. Forward Current
7.00 6.00 Forward Voltage- VF (V) 5.00 4.00 3.00 2.00 1.00 0.00 0 1 2 3 4 5 6 7 Forward Current - IF (A) 30
Capacitance vs. Reverse Voltage
f = 1MHz
L to G 20 L to L
Capacitance - Cj (pF)
Waveform Parameters: tr = 8s td = 20s
10
0 0 1 Reverse Voltage - VR (V) 2 3
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SMF3.3
PROTECTION PRODUCTS Typical Characteristics
Insertion Loss S21, I/O to Ground
CH1 S21 LOG 3 dB/ REF 0 dB
CH1 S21
Insertion Loss S21, I/O to I/O
LOG 3 dB/ REF 0 dB
START. 030 MHz
STOP 3000.000000 MHz
START. 030 MHz
STOP 3000.000000 MHz
Analog Crosstalk (I/O to I/O)
CH1 S21
LOG
20 dB/ REF 0 dB
START. 030 MHz
STOP 3000.000000 MHz
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SMF3.3
PROTECTION PRODUCTS Applications Information
Device Connection for Protection of Four Data Lines The SMF3.3 is designed to protect up to four unidirectional data lines. The device is connected as follows: 1. Unidirectional protection of four I/O lines is achieved by connecting pins 1, 3, 4, and 5 to the data lines. Pin 2 is connected to ground. The ground connection should be made directly to the ground plane for best results. The path length is kept as short as possible to reduce the effects of parasitic inductance in the board traces. Due to the "snap-back" characteristics of the low voltage TVS, it is not recommended that any of the I/O lines be directly connected to a DC source greater than snap-back votlage (VSB) as the device can latch on as described below. EPD TVS Characteristics The SMF3.3 is constructed using Semtech's proprietary EPD technology. The structure of the EPD TVS is vastly different from the traditional pn-junction devices. At voltages below 5V, high leakage current and junction capacitance render conventional avalanche technology impractical for most applications. However, by utilizing the EPD technology, the SMF3.3 can effectively operate at 3.3V while maintaining excellent electrical characteristics. The EPD TVS employs a complex nppn structure in contrast to the pn structure normally found in traditional silicon-avalanche TVS diodes. Since the EPD TVS devices use a 4-layer structure, they exhibit a slightly different IV characteristic curve when compared to conventional devices. During normal operation, the device represents a high-impedance to the circuit up to the device working voltage (VRWM). During an ESD event, the device will begin to conduct and will enter a low impedance state when the punch through voltage (VPT) is exceeded. Unlike a conventional device, the low voltage TVS will exhibit a slight negative resistance characteristic as it conducts current. This characteristic aids in lowering the clamping voltage of the device, but must be considered in applications where DC voltages are present. SMF Circuit Diagram
1
3
4
5
2
Protection of Four Unidirectional Lines
When the TVS is conducting current, it will exhibit a slight "snap-back" or negative resistance characteristics due to its structures. This point is defined on the curve by the snap-back voltage (VSB) and snap-back current (ISB). To return to a non-conducting state, the current through the device must fall below the ISB (approximately <50mA) and the voltage must fall below the VSB (normally 2.8 volts for a 3.3V device). If a 3.3V TVS is connected to 3.3V DC source, it will never fall below the snap-back voltage of 2.8V and will therefore stay in a conducting state.
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SMF3.3
PROTECTION PRODUCTS Applications Information
SMF3.3
Typical Application Diagram
Circuit Board Layout Recommendations for Suppression of ESD. Good circuit board layout is critical for the suppression of ESD induced transients. The following guidelines are recommended: Place the TVS near the input terminals or connectors to restrict transient coupling. Minimize the path length between the TVS and the protected line. Minimize all conductive loops including power and ground loops. The ESD transient return path to ground should be kept as short as possible. Never run critical signals near board edges. Use ground planes whenever possible.
Matte Tin Lead Finish Matte tin has become the industry standard lead-free replacement for SnPb lead finishes. A matte tin finish is composed of 100% tin solder with large grains. Since the solder volume on the leads is small compared to the solder paste volume that is placed on the land pattern of the PCB, the reflow profile will be determined by the requirements of the solder paste. Therefore, these devices are compatible with both lead-free and SnPb assembly techniques. In addition, unlike other lead-free compositions, matte tin does not have any added alloys that can cause degradation of the solder joint.
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SMF3.3
PROTECTION PRODUCTS Outline Drawing - SC-70 5L
DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX
.043 .000 .004 .028 .035 .039 .006 .012 .003 .009 .075 .079 .083 .045 .049 .053 .083 BSC .026 BSC .051 .010 .014 .018 (.017) 5 0 8 .004 .004 .012 1.10 0.00 0.10 0.70 0.90 1.00 0.15 0.30 0.08 0.22 1.90 2.00 2.10 1.15 1.25 1.35 2.10 BSC 0.65 BSC 1.30 BSC 0.26 0.36 0.46 (0.42) 5 0 8 0.10 0.10 0.30
A e1 N 2X E/2 EI E GAGE PLANE 0.15 L (L1) e B D aaa C SEATING PLANE A2 A SIDE VIEW C A1 bxN bbb C A-B D DETAIL c D H
DIM
A A1 A2 b c D E1 E e e1 L L1 N 01 aaa bbb ccc
01
ccc C 2X N/2 TIPS
1
2
A
SEE DETAIL
A
NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD MO-203, VARIATION AA.
Land Pattern - SC-70 5L
X
DIM
C Y P G Z C G P X Y Z
DIMENSIONS MILLIMETERS INCHES
(.073) .039 .026 .016 .033 .106 (1.85) 1.00 0.65 0.40 0.85 2.70
NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET.
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SMF3.3
PROTECTION PRODUCTS Marking Codes
Part Number SMF3.3 Marking Code F03
5
4
F03
1 2 3
Ordering Information
Part Number SMF3.3.TC SMF3.3.TCT Lead Finish SnPb Pb free Qty per Reel 3,000 3,000 R eel Size 7 Inch 7 Inch
Contact Information
Semtech Corporation Protection Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804
www.semtech.com
2008 Semtech Corp.
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