TVS Protection for Wireless Systems

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TVS Protection forWireless Systems
By David W. Hutchins March 2000
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Protection is Requiredat All Levels

• Circuits
• Equipment
• Systems

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Typical Systems

• Portable Telecommunications
• Handheld Devices
• Wireless Phones
• Base Stations

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TVS Components are Needed for

• Smaller, Sensitive IC Components
• Lightning Strikes
• Lower Voltage ESD Failures
• EMC Standards (Enxxxx)

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Design Considerationsfor TVS Protection are

• PCB Layout (Traces, Vias, etc.)
• Grounding Bonding (Return Paths)
• Shielding
• Protection Components

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Typical Interfacewith Single or Multiple I/O
Ports

• Plug-n-play Ports
• Antennas (Bluetooth)
• IC Components for Display
• Base Stations

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Major TVS Locations for TVS Protection

• I/O Ports
• Power Bus
• Ground

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Key TVS Component Parameters
Purpose
Parameter / Test Condition

• Selection
• Application
• Protection

IP _at_ td C _at_ f
VC _at_ IP
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Selection Parameters IP vs td
Compare the threat test conditions to TVS
parameters Peak Pulse Transient Current It
IPP Pulse Time tduration td (20 or 1000 µs)
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Application ParametersC vs f
1000
100
C - Capacitance - pF
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1.0
10KHz 100KHz 1MHz
10MHz 100MHz
1000MHz
f - Frequency - Hz
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Protection Parameter Vc vs IpExample
ESD (HBM) Pulse
20 V/div
Clamping Voltage of SMDA05LCC Test Pulse 10 kV,
1/30 ns (waveshape)
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Review of Major TVS Parameters for comparison
selection
Circuit Threat Conditions Operating Line
Voltage (VOL) Transient Impulse Current (It)
IC Component Threshole Voltage (VFT)
Frequency (F)

• TVS Parameters to
• Stand-off Voltage (VWM)
• Peak Pulse Current (IPP)
• Max. Clamping Voltage (VC)
• Capacitance (C)

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Transient Voltage Suppressor Components

• Avalanche Breakdown Diode (ABD) PCB / Data Bus
  Lines
• ANSI C62.35, IEC 61647-2
• Thyristor Surge Suppressor (TSS) Telecom / Power
  Cross
• ANSI C62.37, IEC 61647-4
• Steering Diode (SD) Arrays High Speed I/O Ports
• TVS / Filter Combination PCB / Data Lines
• Multi-functional Low Capacitance High Speed I/O
  Port Arrays

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Suggested TVS Series for Wireless systems
PSOTxxLC PLCDAxx SMDAxxLCC PSLCxxC
SM16LCxxC P0402FCxxC PSR05C PSDxx
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Suggested TVS devices for Base Stations
15KPAxx 30KPAxx PPxxxxSC PPxxx1SC GPZ532
GPZ1275
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Future Wireless TVS Components will have ...

• Smaller Packages
• Multi-functions
• Lower Cost
• Higher Level of Integration

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Summary
Protection requires...

• Close Inspection of
• Compliance Standards
• System Certification
• Selected parameters of
  TVS components