SGS Thomson Microelectronics CLP270M Datasheet



CLP270M

ApplicationSpecific Discretes

A.S.D.



OVERVOLTAGE AND OVERCURRENT

PROTECTION FOR TELECOM LINE

MAINAPPLICATIONS

Any telecom equipment submitted to transient
overvoltagesandlightningstrikes suchas:

Analogand ISDNline cards
PABX
MainDistribution Frames
Primaryprotection modules

DESCRIPTION

The CLP270M is designed to protect
telecommunicationequipment. It provides both a
transient overvoltage protection and an
overcurrentprotection.
It is housedin a PowerSO-10

TM

package.

FEATURES

DUALBIDIRECTIONALPROTECTIONDEVICE.
HIGHPEAKPULSE CURRENT:

Ipp = 100A(10/1000µs SURGE)
Ipp = 500A(2/10µs SURGE)

MAX.VOLTAGEAT SWITCHING-ON: 380V
MIN.CURRENT AT SWITCHING-OFF : 150mA
FAILURESTATUSOUTPUTPIN

PowerSO-10

SCHEMATICDIAGRAM

1

TIP

S

TIP

L

TIP

L

TIP

L

TABis connected to GND

PRELIMINARY DATASHEET

TM

NCFS
RING

S

RING

L

RING

L

RING

L

BENEFITS

Both primary and secondaryprotectionlevelsin
onedevice.

Voltageand current controlledsuppression.

TM

SurfaceMountingwithPowerSO-10

package.

Line card cost reduction thanks to the very low
power rating of external components required :
balanced resistors, ring relay, low voltage SLIC
protection.

Falls into short circuit if destroyed,still ensuring
protection.

January1998 - Ed: 5B 1/24

CLP270M

COMPLIESWITHTHE

FOLLOWING STANDARDS:

Peak Surge

Voltage

(V)

Voltage

Waveform

(µs)

Current

Waveform

(µs)

Admissible

Ipp

(A)

Necessary

ITUK20 4000 10/700 5/310 100 ­VDE0433 4000 10/700 5/310 100 ­VDE0878 4000 1.2/50 1/20 100 ­IEC-1000-4-5 level4

level4

FCCPart68,lightning surge
type A

FCCPart68,lightning surge

1500

800
100 9/720 5/320 25 -

10/700

1.2/50

10/160
10/560

5/310

8/20

10/160
10/560

100
100

200
100

type B
BELLCORETR-NWT-001089

Firstlevel
BELLCORETR-NWT-001089

2500
1000

2/10

10/1000

2/10

10/1000

500
100

5000 2/10 2/10 500 -

Secondlevel
CNETl31-24 4000 0.5/700 0.8/310 100 -

BLOCKDIAGRAM

Resistor

(Ω)

-

-

-

-

-

-

270

270

Pin Symbol Description

1 FS FailureStatus

2 TIPS TIP (SLICside)
3 / 4/ 5 TIPL TIP (Lineside)
6 / 7/ 8 RINGL

9 RINGS

RING(Lineside)
RING(SLICside)

10 NC Not connected

TAB GND Ground

2/24

CLP270M

APPLICATION NOTE

1.INTRODUCTION
This deviceincludesa primaryprotection level and is suitablefor main distribution frames and line cards.

This protection concept is explained and, in addition, the CLP270M performances are analysed when
facingdifferentsurgesasdescribedin the BELLCOREGR 1089 recommendations.

Fig. 1:

Subscriberline protectiontopology

Telecommunication

line

Telecommunication

line

“PRIMARYPROTECTION”

CLP270M

MDF

EXCHANGE

CLP270M

MDF

EXCHANGE

“SECONDARYPROTECTION”

SLIC

LINE CARD

“SECONDARYPROTECTION”

THDTxx

or

LCP1511D

or

LCDP1511D

LINE CARD

SLIC

Figure1is a simplifiedblock diagramof a subscriberline protectionthatiscommonlyused.
Thisshows two differenttopologies:

A ”primaryprotection”locatedon the Main DistributionFrame(MDF)eliminates coarselythe highenergy
environmentaldisturbances(lightningtransientsand AC power mainsdisturbances)

A ”secondary protection” located on the line card includes a primaryprotectionlevel (first stage) and a
residualprotection(secondstage)which eliminatesfinelytheremainingtransientsthathavenotbeentotally
suppressedbythefirststage.

2. STMicroelectronicsCLP270MCONCEPT

2.1.Evolutionof the SLICprotection

Over the years, t he silicon protect ion pe rformances ha v e co nsiderab ly cha nge d.
The first generation of products like SMTHBTxx and SMTHDTxx offered fixed overvoltage protection

againstsurges on eitherTIPor RINGlinein fourpackages.
The following generation like THBTxx and

THDTxx still offered fixed overvoltage protection
againstsurges on both TIP and RING lines in two
packages.

The next step was the introduction of the
LCP1511D which brought the advantage of full
programmablevoltage.

Today, the CLP270Mcombinesthe features of all
thepreviousgenerations.In additiontothat,itoffers

Fig. 2:

Linecard protection

Programmable

thanks to any

external voltage

reference

+I

SWON

I

Programmable

thanks to an

externalresistor

V

an overcurrentdetection when operatingin speech
modeandalso aFailureStatus output signal.

The figure 2 summarizes the firing modes of the
CLP270M which basically hold the SLIC inside its
correctvoltageand currentvalues.

-I

SWON

Line card
operating
conditions

3/24

CLP270M

2.2Application circuit:CLP270M in line card.
Fig.3 :

TIP

RING

CLP270Min linecard

Fuse

Rsense

TIPL TIPS

Overcurrent

detector

Ov v

RINGS

er oltage

ref

erence

(+/- 270V)

Overvoltage

reference

(+/- 270 V)

Overvoltage

OR

SW3 SW1

FS GND

Fuse

SW4 SW2

RINGL

OR

Overcurrent

Rsense

detector

detector

Overvoltage

detector

I

-Vbat

TIP

-Vbat

(*)

SLIC

RING

Rp

Rp

1

2

1

2

External

voltage

reference

Ring

Generator

(*) LCP1511D orTHDT seriesor LCDP1511D

Figure 3 above shows the topology of a protected analog subscriber line at the exchange side. The
CLP270Misconnectedto theringrelay viatwo balancedRp resistors,and totheSubscriberLine Interface
Circuit. A second device is located near the SLIC : it can be either a LCP1511D, a THDT series or a
LCDP1511D.

Thesetwo devicesare complementaryand their functionsare explainedbelow :

The first stage based on CLP270Mmanages the high powerissued from the external surges. When
used in ringing mode, the CLP270M operates in voltage mode and provides a symmetrical and
bidirectional overvoltage protection at +/- 270 V on both TIP and RING lines. When used in speech
mode, the CLP270Moperates in current modeandthe activationcurrent of the CLP270M is adjusted

sense

.

by R
The second stage is the external voltage reference device which defines the firing threshold voltage

during the speech mode and also assumes a residualpowerovervoltagesuppression. This protection
stage can be either a fixed or programmable breakover device. The THDTxx family acts as a fixed
breakoverdevice whiletheLCP1511Dor the LCDP1511Doperatesas a programmableprotection.

Thankstothistopology, thesurgecurrentinthelineisreducedafterthe CLP270M.Becausetheremaining
surge energy is low, the power ratings of Rp, the ring relay contactsand the external voltage reference
circuitcan bedownsized.Thisresultsin asignificantcost reduction.

4/24

CLP270M

Fig.4:

Switchingby voltageduringringingmode.

ILG

Fuse

TIP

FS

Rsense

TIPL TIPS

Overcurrent

detector

OR

SW3 SW1

Overvoltage

detector

1/2 CLP270M

Overvoltage

reference

(+/- 270V)

GND

ILG

1

Rp

VLG

2

-270

3

A1

2

1

V

+270

2.3.Ringingmode

Inringingmode(Ring relay in position2),the onlyprotectiondeviceinvolvedis theCLP270M.
Innormalconditions, theCLP270M operatesin region1ofA1curve,and is idle.
If an overvoltage occuring between TIP(or RING)andGND reaches the internalovervoltagereference

(+/- 270 V), the CLP270M acts and the line is short-circuited to GND. At this time the operating point
moves to region 2 for positive surges(region 3 fornegativesurges). Once thesurge currentfalls below
the switch offcurrent I

, the devicereturns to its initial state (region 1).

SWOFF

For surges occuring between TIP and RING, the CLP270Macts in the same way. This means that the
CLP270Mensures a tripolarprotection.

Whenused alone, theCLP270Macts at the internalovervoltagereferencelevel (+/- 270 V). Furthermore,
it ispossibleto adjust this thresholdlevel toa lowervoltageby using:

up to 4 fixedexternal voltage reference(V
externalreferencesupplies,V

andVb2(seefig.5b,onnextpage).

b1

toVZ4) (see fig. 5a, here-below).

Z1

Fig.5a: Methodtoadjustthe referencevoltage.

1

2

1

2

TIP

RING

Fuse

Rsense

TIPL TIPS

Overcurrent

detector

detector

RINGS

Overvoltage

reference

(+/- 270 V)

Overvoltage

reference

(+/- 270 V)

detector

Overvoltage

Overvoltage

detector

OR

SW3 SW1

FS GND

SW4 SW2

OR

Overcurrent

RINGL

Rsense

Fuse

Rp

VZ1

VZ2

VZ3

VZ4

Rp

5/24

CLP270M

Fig. 5b:

Methodto adjustthe referencevoltage

TIP

Fuse

Rsense

.

1

Rp

TIPL TIPS

Overcurrent

detector

Overvoltage

detector

Overvoltage

detector

RINGS

RING

OR

SW3 SW1

FS GND

SW4 SW2

RINGL

OR

Overcurrent

detector

Rsense

Fuse

Fig. 6: Switchingby currentduring speechmode.

Fuse

TIP

ILG

Rsense

TIPL TIPS

Overcurrent

detector

Overvoltage

Overvoltage

detector

OR

SW3 SW1

FS

reference

(+/- 270 V)

Rp

VLG

GND

Overvoltage

reference

(+/- 270 V)

Overvoltage

reference

(+/- 270 V)

1

2

Rp

External

voltage

reference

-Vbat

-VREF2

2

VB1

VB2

1

2

ILG

A2

5

4

VREF1

6

V

LG

2.4. Speechmode

Inspeechmode (Ring relay in position 1), the protectionis providedbythe combinationof bothCLP270M
andthe externalvoltagereferencedevice.
Innormalconditions,theworkingpointof thiscircuitis locatedinregion4 ofA2 curve: theCLP270Mis idle.
Whena surgeoccursonthe line,theexternalvoltagereferencedeviceclampsatGND or-V

respectively

bat

forpositiveand negativesurges.
This generates a current which is detected by R

and causes the protection to act : the line is

sense

short-circuitedto GND.
Theoperating point movesto region5 forpositivesurges or region6 for negativesurges.

Oncethe surge currentfalls below the switching-offcurrentI

, the CLP270Mreturnsto its initial state

SWOFF

(region4).

6/24

CLP270M

Fig.7a and7b: Switching-oncurrentversus R

sense

.

ISWON(T,Rsense) / ISWON(25°C,4 )Ω

2

@-20°C @25°C @75°C

1

Iswon @ 25°C (mA)

500
300

Iswonmin

negative

Iswonmax

negative

Iswonmin

positive

Iswonmax

positive

200

0.5

100

0.3

50

0.2
3 5 7 9 11 13

357911

Rsense ( )Ω

Rsense ( )Ω

Thechoice of the switching-oncurrents is functionof theR

sense

resistors.

In normal operating condition the current (typically below -100 mA) should not activate the protection
deviceCLP270M.Thereforethe level ofactivationis tobechosenjustabovethislimit(-200mA).Thislevel
isadjustedthrough R

Figures7a and 7b enable the designerstochoosethe right R

sense

.

value.

sense

EXAMPLE :

ThechoiceofR

=4Ωensuresa negativetriggeringof-190mA minand-320 mAmax.Inthiscase,the

sense

positivetriggeringwillbe 150mAminand280 mA max.

2.5.FailureStatus

TheCLP270Mhasan internalfeaturethat allowsthe usertoget a FailureStatus (FS)indication.Whenthe
CLP270Mis short-circuitingthe line to GND, a signal can be managed through pin 1. This signal can be
used to turn a LED on in order to provide a surge indication.It may also be used with a logic circuitry to
countthenumberof disturbancesappearingon thelines.

If a surge exceeding the maximum ratings of the CLP270M occurs on the line, the device will fail in a
short-circuit state.

Fig.8: FailureStatus circuitand diagnostic.

Fig.9: Operationlimitsanddestructionzoneof the

CLP270M.

FAILURE

STATUS

Rsense

1

CLP270M

1k

Rsense

+12V

5 000
2 000

1 000

500
200

100

50
20

10

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10

t (ms)

Thefigure9 showstwo differentcurves:

The loweroneindicates the maximumguarantedworkinglimitsoftheCLP270M.
The upper curve shows the limit above which the CLP270M is completelydestructed. In thiscase, the

FailDiagnosticpin is on.

7/24

CLP270M

3. CLP270MTESTRESULTSACCORDING TO BELLCORE 1089 REQUIREMENTS.

3.1. BELLCOREGR-1089-CORE requirements:

Table 1: Firstlevel lightningsurge.

Surge Minimum

1 +/-600 100 10/1000 25 A
2 +/-1000 100 10/360 25 A
3 +/-1000 100 10/1000 25 A
4 +/-2500 500 2/10 10 B
5 +/-1000 25 10/360 5 B

Table2:

Secondlevel lightningsurge.

Surge Minimum

peak voltage

(volts)

peakvoltage

(volts)

Minimum

peakcurrent

per conductor

(Amps)

Minimum

peak current

per conductor

(Amps)

Maximumrise

/ Minimum

decay time for

voltageand

current

(µs)

Maximumrise

/ Minimum

decaytimefor

voltageand

current

(µs)

Repetitions,

eachpolarity

Repetitions,

eachpolarity

Test

connections

per

table4.1

Test

connections

per

table4.1

1 +/- 5000 500 2/10 1 B

Tables1 and2 summarizethe lighting surgesrequired by the bellcore 1089.

8/24