LINECARD PROTECTION OVERVOLTAGE OVERCURRENT WITH CLP270M P.Mercer

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LINECARD PROTECTION OVERVOLTAGE OVERCURRENT WITH CLP270M P.Mercer

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AN1220 APPLICATION NOTE
LINECARD PROTECTION OVERVOLTAGE OVERCURRENT WITH CLP270M
P.Merceron A.Bremond
A.S.D
INTRODUCTION This device includes primary protection level suitable main distribution frames line cards. This protection concept explained and, addition, CLP270M performances analysed when facing different surges described BELLCORE 1089 recommendations. Figure simplified block diagram subscriber line protection that commonly used. Fig. Subscriber line protection topology
"PRIMARY PROTECTION"
"SECONDARYPROTECTION"
Telecommunication line
CLP270M
SLIC
LINE CARD
EXCHANGE
"SECONDARY PROTECTION"
Telecommunication
CLP270M
line
THDTxx LCP1511D LCDP1511D LINE CARD
SLIC
EXCHANGE
This shows different topologies
"primary protection" located Main Distribution Frame (MDF) eliminates coarsely high energy environmental disturbances (lightning transients power mains disturbances) "secondary protection" located line card includes primary protection level (first stage) residual protection (second stage) which eliminates finely remaining transients that havenot been totally suppressed first stage.
January 2000
1/13
APPLICATION NOTE
STMICROELECTRONICS CLP270M CONCEPT Evolution SLIC protection Fig. Line card protection Over years, silicon protection Programmab performances have considerably changed. thanks Programmab first generation products like SMTHBTxx external resistor thanks SMTHDTxx offered fixed overvoltage +ISWON external voltage protection against surges either RING line reference four packages. following generation like THBTxx THDTxx still offered fixed overvoltage protection against surges both RING lines SWON packages. next step introduction Line card operating devices which brought advantage full conditions programmable voltage. Today, CLP270M combines features previous generations. addition that, offers overcurrent detection when operating speech mode also Failure Status output signal. figure summarizes firing modes CLP270M which basically holds SLIC inside correct voltage current values.
Fig. CLP270M line card
Fuse
Rsense
TIPL TIPS -Vbat
Overcurrent detector
Overvoltage detector Overvoltage reference (+/- 270V) External voltage reference -Vbat
SLIC
Overvoltage detector Overvoltage reference (+/-
RING
Overcurrent detector Ring Generator
RINGL
RINGS
RING Fuse
Rsense
LCP1511D orTHDT series LCDP1511D
2/13
APPLICATION NOTE
Application circuit: CLP270M line card Figure shows topology protected analog subscriber line exchange side. CLP270M connected ring relay balanced resistors, Subscriber Line Interface Circuit. second device located near SLIC either LCP1511D, THDT series LCDP1511D. These devices complementary their functions explained below first stage based CLP270M manages high power issued from external surges. When used ringing mode, CLP270M operates voltage mode provides symmetrical bidirectional overvoltage protection both RING lines. When used speech mode, CLP270M operates current mode activation current CLP270M adjusted Rsense. second stage external voltage reference device which defines firing threshold voltage during speech mode also assumes residual power overvoltage suppression. This protection stage either fixed programmable breakover device. THDTxx family acts fixed breakover device while LCP1511D LCDP1511D operates programmable protection. Thanks this topology, surge current line reduced after CLP270M. Because remaining surge energy low, power ratings ring relay contacts external voltage reference circuit downsized. This results significant cost reduction.
Fig. Switching voltage during ringing mode.
Fuse
Rsense
TIPL TIPS CLP270M
Overcurrent detector Overvoltage detector Overvoltage reference (+/- 270V)
-270 +270
Ringing mode ringing mode (Ring relay position only protection device involved CLP270M. normal conditions, CLP270M operates region curve, idle. overvoltage occuring between RING) reaches internal overvoltage reference (+/- CLP270M acts line short-circuited GND. this time operating point moves region positive surges (region negative surges). Once surge current falls below switch current ISWOFF, device returns initial state (region surges occuring between RING, CLP270M acts same way. This means that CLP270M ensures tripolar protection. When used alone, CLP270M acts internal overvoltage reference level (+/- Furthermore, possible adjust this threshold level lower voltage using: fixed external voltage reference (VZ1 VZ4) (see fig. here-below). external reference supplies, (see fig. next page).
3/13
APPLICATION NOTE
Fig. Method adjust reference voltage.
Fuse
Rsense
TIPL TIPS
Overcurrent detector
Overvoltage detector
Overvoltage reference (+/-
Overvoltage detector Overvoltage reference (+/-
Overcurrent detector RINGL RINGS
RING Fuse
Rsense
Fig. Method adjust reference voltage.
Fuse
Rsense
TIPL TIPS
Overcurrent detector Overvoltage reference (+/-
Overvoltage detector
Overvoltage detector Overvoltage reference (+/-
Overcurrent detector
RINGL
RINGS
RING Fuse
Rsense
4/13
APPLICATION NOTE
Speech mode speech mode (Ring relay position protection provided combination both CLP270M external voltage reference device (see figure Fig. Switching current during speech mode.
Fuse
Rsense
TIPL TIPS
-Vbat
Overcurrent detector Overvoltage detector Overvoltage reference (+/-
External voltage reference
-VREF2
VREF1
normal conditions, working point this circuit located region curve CLP270M idle. When surge occurs line, external voltage reference device clamps -Vbat respectively positive negative surges. This generates current which detected Rsense causes protection line short-circuited GND. operating point moves region positive surges region negative surges. Once surge current falls below switching-off current ISWOFF, CLP270M returns initial state (region choice switching-on currents function Rsense resistors. normal operating condition current (typically below -100 should activate protection device CLP270M. Therefore level activation chosen just above this limit (-200 mA). This level adjusted through Rsense. Figures enable designers choose right Rsense value. Example: choice Rsense ensures negative triggering -190 -320 max. this case, positive triggering will 150mA max. Fig. Switching-on current versus Rsense.
ISWON Rsense) ISWON (25°C,
@-20°C @25°C @75°C
Iswon 25°C (mA)
Iswon Iswon Iswonmin Iswon negative negative positive positive
Rsense
Rsense
5/13
APPLICATION NOTE
Failure Status CLP270M internal feature that allows user Failure Status (FS) indication. When CLP270M short-circuiting line GND, signal managed through This signal used turn order provide surge indication. also used with logic circuitry count number disturbances appearing lines. surge exceeding maximum ratings CLP270M occurs line, device will fail short-circuit state.
Fig. Failure Status circuit diagnostic.
Rsense FAILURE CLP270M
STATUS
Rsense +12V
Fig. Operation limits destruction zone CLP270M.
figure shows different curves lower indicates maximum guaranted working limits CLP270M. upper curve shows limit above which CLP270M completely destructed this case, Fail Diagnostic
0.01 0.02 0.05 (ms)
CLP270M TEST RESULTS ACCORDING BELLCORE 1089 REQUIREMENTS BELLCORE GR-1089-CORE requirements: Tables summarize lighting surges required bellcore 1089. Tables summarize surge needs defined Bellcore regarding both lightning power fault. case first level test, equipment under test shall operating after surge. second level tests, equipment under test damaged, fire electrical safety hazard occur.
6/13
APPLICATION NOTE
Table First level lightning surge. Surge Minimum peak voltage (volts) Minimum Maximum rise peak current Minimum conductor decay time (Amps) voltage current (µs) 10/1000 10/360 10/1000 2/10 10/360 Repetitions, each polarity Test connections table
1000 1000 2500 1000
Table Second level lightning surge. Surge Minimum peak voltage (volts) Minimum Maximum rise peak current Minimum conductor decay time (Amps) voltage current (µs) 2/10 Repetitions, each polarity Test connections table
5000
Table First level power fault (table GR-1089-CORE issue december 1997). Test Voltage (VRMS) Short circuit current conductor (Amps) 0.33 0.17 600V) Duration Primary protection Test connections table
200, 1000 figure 1000
minutes minutes application each voltage applications applications 0.5s
Removed Removed Removed
figure
Operative protector place Removed Removed Removed Removed Operative protector place
figure
7/13
APPLICATION NOTE
Table Second level power fault (table GR-1089-CORE issue december 1997). Test Test Voltage (VRMS) Short circuit current conductor (Amps) Duration Test connections table
Secondary contact Primary contact Short-term fault induction Long-term fault induction High impedance induction
120, 100-600
minutes seconds seconds minutes minutes
Table Test connection (table GR-1089-CORE). Test Two-wire interface generator, Ring ground Ring generator, ground generator, Ring generator simultaneously generator, Ring generator simultaneously Four-wire interface Each lead generator with other three leads grounded Ring generator simultaneously, ground generator simultaneously, Ring ground generator simultaneously
Switch unit under test
Limiting resistance specified)
Voltage Source
Test
8/13
APPLICATION NOTE
Table Application lightning power fault test voltages (table GR-1089-CORE). Test generator, ground (condition table 4-1) generator, ground (condition table 4-1) generator, generator simultaneously (condition table 4-1) First level lightning surge: 2.1. Ringing mode Lightning phenomena most common surge causes. purpose this test check behavior CLP270M against these lightning strikes. Figures show that remaining overvoltage does exceed CLP270M switches within 250ns withstands 500A given BELLCORE 2/10µs generator. Closed Open Closed Open Closed Open Open Closed Closed Closed Open Open
Fig. Lightning simulation test.
2/10 GENERATOR (500 TIPL
Rsense TIPS
CLP270M
Fig. CLP270M response positive surge.
Fig. CLP270M response negative surge.
9/13
APPLICATION NOTE
Fig. Lightning test speech mode.
2/10 GENERATOR (500 TIPL CLP270M Rsense TIPS -48V LCP1511D SLIC
2.2. Speech mode Figures give voltage current behavior during positive negative 2.5kV, 2/10µs, 500A surge tests using LCP1511D second stage protection device. firing threshold values adjusted -Vbat (-48V) action second stage protection which acts external voltage reference. shown these figures, maximum remaining voltage does exceed +8.5V positive surges -65V negative surges. Fig. CLP270M response positive surge. Fig. CLP270M reponse negative surge.
10/13
APPLICATION NOTE
Second level lightning surge 3.1. Lightning test ringing mode figures give voltage current behavior during positive negative 5kV, 2/10µs,500A surge with CLP270M acting Ringing mode. Fig. Lightning test Ringing mode.
2/10 GENERATOR (500 TIPL
Rsense TIPS
CLP270M
Fig. CLP270M response positive surge.
Fig. CLP270M response negative surge.
3.2. Speech mode figures give voltage current behavior during positive negative 5kV, 2/10µs,500A surge with CLP270M acting speech mode. CLP270M withstands second level lightning surge test without trouble both ringing speech mode.
11/13
APPLICATION NOTE
Fig. Lightning test Speech mode.
2/10 GENERATOR (500 TIPL
Rsense TIPS
SLIC
CLP270M
-48V LCP1511D
Fig. CLP270M response positive surge.
Fig. CLP270M response negative surge.
First second level Power fault. 4.1. Ringing mode figures give voltage current CLP270M terminals Ringing mode Speech mode. Fig. power fault test Ringing mode. Fig. Example behavior when facing test (400V, 600).
Rsense
TIPL TIPS CLP270M
V(RMS) 50Hz
12/13
APPLICATION NOTE
Fig. power fault test Speech mode. Fig. Example behavior when facing test (400V, 600).
TIPL V(RMS)
Rsense
SLIC
TIPS -48V LCP1511D
CLP270M
CONCLUSION CLP270M able withstand first level power fault tests required table GR-1089-CORE standard, then suitable protect linecard. usual, second level power fault tests serial protection fuse needed. these curves, lightning power fault represent behavior CLP270M worst case tests, anyhow CLP270M withstands others surges Bellcore GR1098 standard. second level power fault test, series protection elements (PTC fuses) needed. allows system monitor record number surges occuring telecom line.
Information furnished believed accurate reliable. However, STMicroelectronics assumes responsibility consequences such information infringement patents other rights third parties which result from use. license granted implication otherwise under patent patent rights STMicroelectronics. Specifications mentioned this publication subject change without notice. This publication supersedes replaces information previously supplied. STMicroelectronics products authorized critical components life support devices systems without express written approval STMicroelectronics.
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LINECARD PROTECTION OVERVOLTAGE OVERCURRENT WITH CLP270M P.Mercer

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