APPLICATION NOTE
Integrated Overcurrent / Overvoltage Protection Device
Helps Protect Telecommunications Equipment
Customer premise telecom equipment must meet the
requirements of UL/IEC 60950, ATIS/TIA-968B and ITU-T
K.21 as specified by network operators and consumer safety
agencies. Central office and network equipment must comply
with regional telecom requirements standards such as
Telcordia GR-1089 and ITU-T Recommendation K.20. These
standards have performance requirements. To meet these
performance requirements may require the use of protection.
The use of overvoltage and overcurrent circuit protection
assists in providing reliable equipment performance and
personnel safety.
Damage by surge anomalies to telecommunications equipment
may occur as a result of lightning and ESD (electrostatic
discharge) surges, power contact and induction with AC lines.
Metal Oxide Varistors (MOVs) are typically used for transient
overvoltage suppression, but in many line-voltage applications
there also exists the potential for a sustained abnormal
overvoltage/limited current condition that may cause the
MOV to go into thermal runaway, resulting in overheating,
outgassing and possibly a more sever outcome.
TE’s 2Pro device helps protect telecom equipment from damage caused by
overcurrent and overvoltage events.
An integrated-device approach was developed by TE Circuit
Protection to help manufacturers meet industry test requirements,
technology with the MOV, the 2Pro device helps improve
reduce component count, and improve equipment reliability. The
overcurrent and thermal protection under conditions where the
2Pro device combines a polymeric positive temperature
MOV is exposed to prolonged continuous overvoltage events.
coefficient (PPTC) overcurrent component with an MOV
In the event of an overvoltage transient, such as a loss of
component into one thermally protected device, helping to
neutral event, the PPTC element of the 2Pro device heats up,
provide resettable current limiting for overcurrent conditions
trips and goes into a high-resistance state, helping to reduce
and voltage clamping during overvoltage events.
the risk of MOV device failure.
The 2Pro device helps manufacturers comply with UL/IEC 60950
How It Works
and IEC 60335 and helps equipment remain operational after
Although the AC line voltage applied to an MOV is not
specified lightning tests according to IEC 61000-4-5. Also,
generally expected to exceed the device’s maximum
because the PPTC element is in series with the MOV, no
continuous operating voltage rating, overvoltage transients may
additional overcurrent protection is required, which helps
occur that exceed these limits. By integrating PPTC
reduce component count and optimize board space.
www.circuitprotection.com
Figures 1 and 2 below show how the 2Pro TM2P10-271 device,
Benefits
which utilizes a 260VDC varistor, helps provide overcurrent and
• Helps provide overcurrent, overvoltage and ESD protection
overvoltage protection in both grounded and ungrounded
• Helps reduce component count and footprint
telephony applications.
• Helps reduce warranty returns
• Helps equipment comply with surge tests per: TIA-968-B,
2 Pro Device
UL/IEC 60950, ITU-T K.20/K.21
• Helps simplify UL/IEC 60950 testing
Telecom
Line
Telecom
Equipment
(T)
2 Pro Device
(R)
• Helps equipment comply with UL/IEC 60950
Applications
• VoIP gateways
• Data modems
• Set-top boxes
• Cordless phones
Figure 1
2Pro device in grounded system.
• Security systems
• MDF (Main Distribution Frame) modules
2 Pro Device
• Analog linecards
• ISDN (Integrated Services Digital Network) linecards
Telecom
Equipment
(T)
Telecom
Line
(R)
Figure 2
2Pro device in ungrounded system.
TE Circuit Protection
308 Constitution Drive
Menlo Park, CA USA 94025-1164
Tel : (800) 227-7040, (650) 361-6900
Fax : (650) 361-4600
www.circuitprotection.com
www.circuitprotection.com.hk (Chinese)
www.te.com/japan/bu/circuitprotection (Japanese)
2Pro, TE Connectivity, TE connectivity (Logo) and TE (logo) are trademarks of the TE Connectivity Ltd. family of companies. Other logos, product and company names mentioned herein may be trademarks of their respective owners. All information, including
illustrations, is believed to be accurate and reliable. However, users should independently evaluate the suitability of each product
for their application. Tyco Electronics Corporation and/or its Affiliates in the TE Connectivity Ltd. family of companies (“TE”) makes
no warranties as to the accuracy or completeness of the information, and disclaims any liability regarding its use. TE’s only obligations are those in the TE Standard Terms and Conditions of Sale and in no case will TE be liable for any incidental, indirect, or consequential damages arising from the sale, resale, use, or misuse of the product. Specifications are subject to change without notice.
In addition, TE reserves the right to make changes without notification to Buyer — to materials or processing that do not affect compliance with any applicable specification.
©2011 Tyco Electronics Corporation, a TE Connectivity Ltd. company. All rights reserved. RCP0082E.0810