L3845 [STMICROELECTRONICS]

TRUNK INTERFACE; Trunk接口


型号：	L3845
厂家：	ST
描述：	TRUNK INTERFACE Trunk接口
文件：	总7页 (文件大小：60K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

L3845

TRUNK INTERFACE

ON CHIP POLARITYGUARD

MEETS DC LINE CHARACTERISTICS OF

EITHER CCITT AND EIA RS 464 SPECS

PULSE FUNCTION

HIGH AC IMPEDANCE

OFF HOOK-STATUS DETECTION OUTPUT

LOW EXTERNAL COMPONENT COUNT

Minidip

SO8

DESCRIPTION

The circuit provides DC loop termination for ana-

log trunklines.

ORDERING NUMBERS:

L3845B

L3845D

The V-I characteristics is equivalent to a fixed

voltage drop (zener like characteristic) in series

with an external resistance that determines the

slope of the DC characteristic.

An external low voltage electrolytic capacitor

causes the circuit to exhibit a very high imped-

ance to all AC signal above a minimum frequency

that is determinedby the capacitor itself and by a

20 K nominal resistor integrated on the chip.

The Off-Hook status is detected all the time a

typic of 8 mA is flowing into the circuit. In this con-

dition a constant current generator is activated to

supply an external device (typically an optocou-

pler) without affecting the AC characteristic of the

circuit.

When Pulse Dialing is required the PULSE input

(pin 3) connected to V- causes the device to re-

duce the fixed DC voltage drop and to exhibit a

pure resistive impedance equal to the external re-

sistor.

BLOCK DIAGRAM

V+

IN1

PULSE

DC LINE

TERMINATION

POLARITY

GUARD

OF HOOK

DETECTION

CIRCUIT

HD0

IN2

ACT

DCT

V-

D96TL263

1/7

June 1996

This is advanced information on a new product now in development or undergoingevaluation. Details are subject to change without notice.

L3845

ABSOLUTE MAXIMUM RATINGS

Symbol

Parameter

Value

Unit

V_L

I_L

Max Line Voltage (pulse duration 10 ms max)

Max Line Current

150

°C

P_tot

Total Power Dissipation at Tamb = 70 °C

Operating Temperature

800

T_op

– 40 to + 70

– 55 to + 150

T_srg, T_j

Storage and Junction Temperature

°C

PIN CONNECTION (Topview)

THERMAL DATA

Symbol

Parameter

Thermal Resistance Junction-ambient (*)

Minidip

SO8

Unit

R_{th j-amb}

Max.

140 to 180

C/W

(*) Mounted on FR4 Boards

2/7

L3845

DC ELECTRICAL CHARACTERISTICS

unless otherwise specified)

Ω

(I_L= 10 mA to 100 mA, R₁= 56 , S₁= Open, T_amb= + 25 C,

Symbol

Parameter

Line Voltage

Test Condition

PULSE = Open

Min.

Typ.

Max.

Unit

V_L

(normal mode)

IL = 10 mA

I_L= 20 mA

I_L= 100 mA

V_LP

Line Voltage

(pulse mode)

PULSE = V^–

I_L= 20 mA

I_L= 35 mA

I_L= 80 mA

5.5

9.5

I_hn

ON/OFF-Hook

Line Current Detection

Threshold

6.5

9.5

9.2

I_hf

OFF/ON-Hook

Line Current Detection

Threshold

I_OUT

OFF-Hook

Output Drive Current at Pin

HDO

IL = 10 mA

I_L20 mA

≥

1.5

V_PM

I_PM

Pulse Input Low Voltage

0.8

Pull-up Input Current at Pin

PULSE (pulse mode)

IL = 100 mA

Pulse = V^–

µA

I_NM

Imput Current at Pin Pulse

(normal mode)

AC ELECTRICAL CHARACTERISTICS (I_L= 10mA to 100mA, R₁= 56Ω, R₂= 470KΩ, R₃= 130 KΩ,

_amb= + 25 °C, unless otherwise specified)

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

Z_L

AC Line Impedance

S₁= Open, S₂= Open

C₁= 2.2mF

f = 1KHz

Ω

Sending/Receiving Distortion

S₁= Open, S₂= Open

f = 1KHz

_AC-L= 775mVrms

I_L= 15 to 100mA

Sending/Receiving Distortion

S₁= Closed; S₂= Open

_AC-L= 1.3Vrms

S₁= Open; S₂= Closed

_AC-L= 1.9Vrms

2(*)

(*) Not tested, guaranteed only by design.

APPLICATION INFORMATION

Figure 1 gives the typical application circuit ; it is

worth to note that the TRUNK TERMINATION

CIRCUIT, togetherwith the LS5018 transient sup-

pressor provides a compact and low cost module

fully protected against lightning or overvoltages

frequently present on telephonelines.

The PULSE input when connected to V- allows

the device to reduce the Line Voltage and to

show a resistive impedance equal to R1 to the

line. When PULSE input is left open, this function

is disable.

With the use of this circuit it is possible to termi-

nate an analog trunk so that all the DC current

component is flowing in the TRUNK TERMINA-

TION CIRCUIT while the AC component is de-

coupled with a low voltage capacitor and can be

used with a small and low cost audio coupler

transformer to provide the AC balancing termina-

tion and two to four wire conversion.

Therefore it is usefull both for MODEM and PABX

systems.

3/7

L3845

Figure 1:

Typical Application.

4/7

L3845

MINIDIP PACKAGE MECHANICAL DATA

inch

Typ.

DIM

Min.

Typ.

Max.

Min.

Max.

3.32

0.131

0.51

1.15

0.020

0.045

0.014

0.008

1.65

0.55

0.065

0.022

0.012

0.430

0.384

0.356

0.204

0.304

10.92

9.75

7.95

0.313

2.54

7.62

0.100

0.300

6.6

0260

0.200

0.150

0.060

5.08

3.81

1.52

3.18

0.125

5/7

L3845

SO8 PACKAGE MECHANICAL DATA

inch

Typ.

DIM

Min.

Typ.

Max.

1.75

0.25

1.65

0.85

0.48

0.25

0.5

Min.

Max.

0.069

0.010

0.065

0.033

0.019

0.010

0.020

0.1

0.004

0.65

0.35

0.19

0.25

0.026

0.014

0.007

0.010

45^o(typ.)

4.8

5.8

5.0

6.2

0.189

0.228

0.197

0.244

1.27

3.81

0.050

0.150

3.8

0.4

4.0

1.27

0.6

0.150

0.016

0.157

0.050

0.024

8^o(max.)

6/7

L3845

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no

responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third

parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights

of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice.

This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics prod-

ucts are not authorized for use as critical components in life support devices or systems without express written ap-

proval of SGS-THOMSON Microelectronics.

SGS-THOMSON Microelectronics GROUP OF COMPANIES

Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Nether-

lands

Singapore - Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A.

7/7

L3845 [STMICROELECTRONICS]

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