Introduction to Tertiary Telecom Protection

2 Version01_ 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 Version01_ Building Entrance Line Card Primary / Secondary / Tertiary Protection Protection is a coordinated layering of protection technologies Primary Protection OVP ~ 1000V Thermal Overload UL NEBS GR-974 Secondary Protection OVP ~ 300V OCP ~ Fuse / PTC GR-1089 UL ITU K.20 / K.21 Tertiary Protection OVP ~ 30V No Regulatory Need Outdoor Cabling Tertiary protection is unique in that the performance requirements are dictated only by the customer’s perceived need.

4 Version01_ Transformer Coupled Applications Tertiary protection circuits are separated from the secondary protection circuits by a transformer: xDSL T1 / E1 Ethernet 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 Version01_ 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 Version01_ Rail Clamp Protection Line Drivers Transceiver PHY Power Supply +V -V Digital Circuitry Surge Energy Rail Clamp Protection Strategy: –Dump Energy Into Power Supply Rails Through Steering Diodes Littelfuse offers several Rail Clamp Diode Arrays that combine Steering and TVS diodes Differential Energy: Through transformer magnetics Common-Mode Energy: Through inter-winding capacitance.

7 Version01_ Differential Protection Line Drivers Transceiver PHY Power Supply +V -V Digital Circuitry Surge Energy Differential Protection Strategy: –Absorb Energy Directly Differential Protection:  Does not protect against common-mode energy  Can not deliver energy to downstream components Littelfuse offers several Differential Protection devices for tertiary protection

8 Version01_ Driver Voltages & Protection Voltages There are a variety of supply voltages for drivers: Driver Type Typical Power Rail Voltage Ethernet PHY2.8, 3.3, 5.0 T1 / E1 / T35.0 xDSL (CPE End) 6, 7, 12 xDSL (CO End) 6, 12, 16, 20, 24 Two KEY Points… Protection V DRM or V RWM must be higher than the driver voltage. Relative protection effectiveness comes from comparing V C or V S on identical test waveforms.

9 Version01_ Capacitance Issues  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 There is a natural trade-off between surge capability, capacitance and clamp voltage: High Surge  High Capacitance  Low Clamp Voltage

10 Version01_ 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 Version01_ 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 Version01_ SDP0242Q12F  The only Littelfuse solution for drivers above 5V  Pure differential protection  Designed for VDSL applications

13 Version01_ SP03 Family  Available in 3.3V, 6 and 8V V RWM  Differential Protection  Grounded Bridge Option  150A 8x20 Surge Rating  SO-8 Packaging

14 Version01_ SP300x Family  Rail Clamp or Differential Protection  Variety of SMT Packaging  Ultra-Low Capacitance  Limited Surge Capability

15 Version01_ SP3050  Rail Clamp or Differential Protection  Good Parameter Balance: –Mid-Capacitance –Mid-Surge  SOT23-6 Packaging

16 Version01_ Tertiary Protection Selection Driver Voltage Clamp Voltage Surge Withstand (8x20) Capacitance (0V) Circuit Configuration P0080 Family 0 - 6V 25V (100V/uS) 150A53pFDifferential SP300x0 - 6V 10.6 – 11.8V (2A 8x20) 2.5 – 4.5A0.35 – 0.50 pF Rail Clamp Diode Array SP V 13.2V (8A 8x20) 10A1.2pF Rail Clamp Diode Array SP SP03-6 SP V 0 - 6V 0 - 8V 18V - 22V (100A 8x20) 150A8pF Grounded Diode Array SDP0242Q12F V 43V (100V/uS) 80A15pFDifferential

17 Version01_ Thank You! Tertiary Telecom Protection