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Introduction to Tertiary Telecom Protection

Introduction to Tertiary Telecom Protection. Outline. Tertiary Telecom Protection Primary / Secondary / Tertiary Transformer Coupled Applications Tertiary Protection Requirements Differential vs Rail Clamp Diode Array Protection Driver Voltages & Vdrm vs Vs

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Introduction to Tertiary Telecom Protection

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  1. Introduction to Tertiary Telecom Protection

  2. Outline • Tertiary Telecom Protection • Primary / Secondary / Tertiary • Transformer Coupled Applications • Tertiary Protection Requirements • Differential vs Rail Clamp Diode Array Protection • Driver Voltages & Vdrm vs Vs • Low Capacitance / Flat Capacitance • Littelfuse Tertiary Protection Products • P0080SAMC Family • SDP0242Q12F • SP03 Family • SP300x Family • SP3050 • Selection Table

  3. Primary / Secondary / Tertiary Protection Building Entrance Line Card • Primary Protection • OVP ~ 1000V • Thermal Overload • UL • NEBS • GR-974 • Secondary Protection • OVP ~ 300V • OCP ~ Fuse / PTC • GR-1089 • UL 60950 • ITU K.20 / K.21 • Tertiary Protection • OVP ~ 30V • No Regulatory Need Protection is a coordinated layering of protection technologies Outdoor Cabling Tertiary protection is unique in that the performance requirements are dictated only by the customer’s perceived need.

  4. T1 / E1 Ethernet Transformer Coupled Applications xDSL Tertiary protection circuits are separated from the secondary protection circuits by a transformer: • Tertiary protection is used to protect the signal driver circuitry. • T1/E1 circuits call this the transceiver. • xDSL circuits use line drivers. • Ethernet uses a PHY.

  5. Tertiary Protection Requirements • Tertiary protection requirements come from four considerations: • The nature of the threats to the protection scheme. • ESD only? Or AC Power Cross? Lightning Exposure? • The amount of energy coupled through the transformer. • Primary / Secondary Technology & Topology. • The protection requirements of the protected driver circuitry. • Operating Voltages / Damaging Voltages • The nature of the datastream being protected. • The Protection Scheme Must NOT Interfere!

  6. Rail Clamp Protection Littelfuse offers several Rail Clamp Diode Arrays that combine Steering and TVS diodes +V Rail Clamp Protection Strategy: • Dump Energy Into Power Supply Rails Through Steering Diodes Power Supply Digital Circuitry Line Drivers Transceiver PHY Surge Energy -V Differential Energy: Through transformer magnetics Common-Mode Energy: Through inter-winding capacitance.

  7. Differential Protection Littelfuse offers several Differential Protection devices for tertiary protection +V Differential Protection Strategy: • Absorb Energy Directly Power Supply Digital Circuitry Line Drivers Transceiver PHY Surge Energy -V Differential Protection: • Does not protect against common-mode energy • Can not deliver energy to downstream components

  8. Driver Voltages & Protection Voltages • Two KEY Points… • Protection VDRM or VRWM must be higher than the driver voltage. • Relative protection effectiveness comes from comparing VC or VS on identical test waveforms. There are a variety of supply voltages for drivers:

  9. Capacitance Issues There is a natural trade-off between surge capability, capacitance and clamp voltage: High Surge  High Capacitance  Low Clamp Voltage • High Capacitance will rob power from the signal. • Capacitance gains in importance as the data rate of the signal increases. • Non-Issue for Voice, T1/E1 • Minor Issue for T3, ADSL • Major Issue for VDSL, Ethernet • Higher capacitance devices should minimize how much their capacitance varies with applied voltage. • Use steering diodes • Use devices in series

  10. Outline • Tertiary Telecom Protection • Primary / Secondary / Tertiary • Transformer Coupled Applications • Tertiary Protection Requirements • Differential vs Rail Clamp Diode Array Protection • Driver Voltages & Vdrm vs Vs • Low Capacitance / Flat Capacitance • Littelfuse Tertiary Protection Products • P0080SAMC Family • SDP0242Q12F • SP03 Family • SP300x Family • SP3050 • Selection Table

  11. P0080SAMC • Relatively high capacitance  Low speed apps • Very high surge capability • Low voltage drivers only • Pure differential protection • SMB, QFN or TO-92 Packaging

  12. SDP0242Q12F • The only Littelfuse solution for drivers above 5V • Pure differential protection • Designed for VDSL applications

  13. SP03 Family • Available in 3.3V, 6 and 8V VRWM • Differential Protection • Grounded Bridge Option • 150A 8x20 Surge Rating • SO-8 Packaging

  14. SP300x Family • Rail Clamp or Differential Protection • Variety of SMT Packaging • Ultra-Low Capacitance • Limited Surge Capability

  15. SP3050 • Rail Clamp or Differential Protection • Good Parameter Balance: • Mid-Capacitance • Mid-Surge • SOT23-6 Packaging

  16. Tertiary Protection Selection

  17. Thank You! Tertiary Telecom Protection

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