L3037 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

L3037

SUBSCRIBER LINE INTERFACE CIRCUIT

STMicroelectronics 

L3037

EXTERNAL COMPONENTS

Name

Function

Formula

Typ. Value

CVB Battery Filter

330nF 20% 63VI

CVDD Positive Supply Filter

100nF 20%

CVSS Negative Supply Filter

100nF 20%

RREF Internal Current Reference

23.7K 1%

CSVR Battery Ripple Rejection

CSVR = 1/(6.28 * fp * 150K)

@ fp = 1.6Hz

680nF

20% 60VI

CRT

RDC

Ring Trip & Ground-key Capacitor

DC Feeding Resistance

CRT = (25/fRING) ⋅ 390nF

RDC = 10 * (Rfeed - 2Rp)

390nF 20% 6VI

3.2K 1%

CAC AC/DC Splitter

CAC = 1 / (6.28 * fsp * RDC)

@ fsp = 10Hz

4.7µF

20% 15VI

RS Protection Resistor Image

RS = 50 * 2RP

4K 1%

ZAC 2 Wire AC Impedance

ZAC = 50 * (Zs-2Rp)

26K 1%

ZA (1) SLIC Impedance Balancing Network ZA = 50 * (Zs-2Rp)

26K 1%

RA (1) SLIC Impedance Balancing Network RA = 50 * 2Rp

4K 1%

ZB (1) Line Impedance Balancing Network ZB = 50 * Zl

30K 1%

CCOMP AC Feedback Compensation

CCOMP = 1 / [2Πfo (100 Rp)]

@ fo = 250KHz

220pF

2 0%

CH (1) Trans-hybrid Loss Frequency

Compensation

CH = CCOMP

220pF 20%

RF Feeding Resistance for Ring Inj.

≥ 200Ω (7)

200Ω 2W

RT Feeding Resistance for Ring Inj.

≥ 200Ω (7)

200Ω 2W

RRG Ring Input Resistor

RRG = (VRING/25µA)cos[-2⋅fRING ⋅ T ⋅

180] (4)

4MΩ 5%

CRG Ring Input Capacitor

PTC (2) Positive Temp. Coeff. Resistor

CRG = 25µA/(VRING ⋅ sin[2 ⋅ fRING⋅T ⋅

180] ⋅ 2ΠfRING) (4)

< 15Ω

3.9nF 20% 100V

10Ω

RST (2) Tip Buffer Sensing Resistor

10 to 50KΩ

33K 1W 5% (6)

RSR (2) Ring Buffer Sensing Resistor

10 to 50KΩ

33K 1W 5%(6)

QEXT External Transistor (3)

(*)

Rp Protection Resistor

30 to 80Ω (8)

40Ω

RTTX Teletax Cancellation Resistor

RTTX = 21.5 ⋅ [Re (Zlttx) +2Rp] (5)

6.34K 1%

CTTX Teletax Cancellation Capacitor

CTTX = 1/(21.5 ⋅ [–Im(Zlttx) ⋅ fttx ⋅ 6.28])

(5)

5.6nF 20%

D1

CREV

Relay Kickback Clamp Diode

Polarity Reversal Transition Time

Programming

CREV =

K

∆VTR⁄ ∆T

;

K = 2 ⋅ 10-4

1N4148

47nF

Notes:

(1) These components can be removed and ZB pin shorted to GND when 2/4wire conversion is implemented with 2nd generation COMBO (EG.

TS5070FN)

(2) In case there is no necessity to recover the unbalance introduced by PTC tolerance pins TIP and STIP can be shorted togheter as pins

RING and SRING. In this case also the RP Resistor should be splitted in two parts keeping at least 20Ω between TIP/RING terminals and

protection connection. In this case PTC or fuse resistor (if used) can be placed in series to Rp.

(3) Transistor characteristic: PDISS = 1W (typ. depending on application); hFE ≥ 25; IC ≥ 100mA; VCEO ≥ 60V; fT ≥ 15MHz.

(4) VRING: Max Ring Generator Voltage, fRING: Ring Frequency, T: relay response time.

Typical value obtained for VRING = 100Vrms, fRING = 25Hz; T = 2.5ms.

(5) Defining RTTX + CTTX = ZTTX, RTTX and CTTX can also be calculated from the following formula: ZFTTX = 21.5 [Zlttx + 2Rp].

(6) RST and RSR wattage should be calculated according to the power cross test specification. (When PTC become open circuit the entire

power cross voltage will appear across RSR and RST).

(7) In order to optimize the component count it is also possible to use only one resistor in series to the ringing generator. In this case RT = 0Ω;

RF≥ 400Ω (RF typ. value = 400Ω).

(8) Suggested Rp type are 2W wire wound resistors or thick film resistors on ceramic substrate.

Fuse function should be included if PTC are not used.

(*) ex: BD140; MJE172;MJE350....(ST32 or SOT82 package available also for surface mount).

For low power application (reduced battery voltage) BCP53 (SOT223 surface mount package) can be used.

8/22

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