Introduction to Tertiary Telecom

Protection

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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

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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 60950• 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.

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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.

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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!

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Rail Clamp Protection

Line Drivers

Transceiver

PHY

Po

wer S

up

ply

+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 magneticsCommon-Mode Energy: Through inter-winding capacitance.

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Differential Protection

Line Drivers

Transceiver

PHY

Po

wer S

up

ply

+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

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Driver Voltages & Protection Voltages

There are a variety of supply voltages for drivers:

Driver TypeTypical Power Rail

Voltage

Ethernet PHY 2.8, 3.3, 5.0

T1 / E1 / T3 5.0

xDSL (CPE End)

6, 7, 12

xDSL (CO End)

6, 12, 16, 20, 24

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.

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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

SIDACtor Capacitance vs Line Voltage

0

10

20

30

40

50

60

70

80

90

100

0.1 1 10 100Line Voltage

pF

P0080SAMC

P0080SCMC

P0300SAMC

P0300SCMC

P0640SCMC

P2600SCMC

P3100SCMC

P3100D

P3500SCMC

There is a natural trade-off between surge capability, capacitance and clamp voltage:

High Surge High Capacitance Low Clamp Voltage

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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

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P0080SAMC

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

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SDP0242Q12F

The only Littelfuse solution for drivers above 5V Pure differential protection Designed for VDSL applications

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SP03 Family

Available in 3.3V, 6 and 8V VRWM

Differential Protection Grounded Bridge Option 150A 8x20 Surge Rating SO-8 Packaging

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SP300x Family

Rail Clamp or Differential Protection Variety of SMT Packaging Ultra-Low Capacitance Limited Surge Capability

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SP3050

Rail Clamp or Differential Protection Good Parameter Balance:

– Mid-Capacitance– Mid-Surge

SOT23-6 Packaging

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Tertiary Protection Selection

Driver Voltage

Clamp Voltage

Surge Withstand

(8x20)

Capacitance(0V)

Circuit Configuration

P0080 Family

0 - 6V 25V(100V/uS)

150A 53pF Differential

SP300x 0 - 6V 10.6 – 11.8V(2A 8x20)

2.5 – 4.5A 0.35 – 0.50 pFRail Clamp Diode Array

SP3050 0 - 6V 13.2V(8A 8x20)

10A 1.2pFRail Clamp Diode Array

SP03-3.3

SP03-6

SP03-8

0 - 3.3V

0 - 6V

0 - 8V

18V - 22V(100A 8x20)

150A 8pFGrounded Diode

Array

SDP0242Q12F 0 - 24V 43V(100V/uS)

80A 15pF Differential

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Thank You!

Tertiary Telecom Protection