LS256 STMICROELECTRONICS | Alldatasheet

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TELEPHONE SPEECH CIRCUIT WITH MULTIFREQUENCY .PRESENTSTHE PROPER DC PATHFOR THE LINE CURRENT .HANDLES THE VOICE SIGNAL, PERFORM- ING THE 2/4 WIRES INTERFACE AND CHANGING THE GAIN ON BOTH SENDING AND RECEIVING AMPLIFIERS TO COMPEN- SATE FOR LINE ATTENUATION BY SENSING THELINELENGTHTHROUGHTHELINECUR- RENT .ACTS AS LINEAR INTERFACE FOR MF, SUP- PLYINGA STABILIZEDTO THE DIGITALCHIP AND DELIVERING TO THE LINE THE MF TONE GENERATED BY THE DIALER

DESCRIPTION

The LS256 is a monolithic integrated circuit in 16- lead dual in-line and SO20 plastic packages to re- placethe hybridcircuit in telephoneset.It workswith the same type of transdurcers for both transmitter and receiver (typically piezoceramic capsules, but DIP16 ORDERING NUMBERS : LS256B LS256D the devicecan work also with dynamic ones).Many of its electrical characteristics can be controlled by means of external components to meet different specifications. In addition to the speech operation, the LS256 acts as an interface for the MF tone signal. PIN CONNECTIONS (top view) DIP16 SO20 N.C. MIC. INPUT +LINE MUTING BIAS ADJ. DC. REGULATOR SHUNT REG. BYPASS LINE CURRENT SENSING GAIN CONTROL -LINE INPUT-(REC.AMP.) INPUT+(REC.AMP.) RECEIVER OUTPUT RECEIVER OUTPUT MF INPUT VDD MIC. INPUT N.C.1 N.C. N.C. D96TL274 SO20

BLOCK DIAGRAM (ref. to DIP16) ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit V L Line Voltage (3ms pulse duration) 22 V IL Forward Line Current 150 mA IL Reverse Line Current – 150 mA Ptot Total Power Dissipation at Tamb =7 0°C1 W Top Operating Temperature – 45 to 70 °C Tstg,T j Storage and Junction Temperature – 65 to 150 °C THERMAL DATA Symbol Parameter DIP16 SO20 Unit R th j-amb Thermal Resistance Junction-ambient Max 80 150 °C/W LS256

Figure 1. Figure 2.

Figure 3. Figure 4. Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig.

ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig. SPEECH OPERATION (continued) G R Sidetone F = 1kHz, T amb =2 5°C, S1 in (b) IL = 52mA IL = 25mA dB 2 ZML Line Matching Impedance V RI = 0.3V, f = 1kHz IL = 12 to 80mA 500 600 700 Ω MULTIFREQUENCY SYNTHESIZER INTERFACE VDD MF Supply Voltage (standby and operation) IL = 12 to 80mA 2.4 2.5 V IDD MF Supply Current Stand by Operation IL = 12 to 80mA IL = 12 to 80mA ; S2 in (b) 0.5 mA mA MF Amplifier Gain I L = 12 to 80mA, fMF in = 1kHz VMF in = 80mV 15 17 dB 4 VI DC Input Voltage Level (pin 14) VM Fin = 80mV 3V DD V R I Input Impedance (pin 14) V M Fin = 80mV 40 k Ω d Distortion V M Fin = 110mV IL = 12 to 80mA 2% 4 Starting Delay Time I L = 12 to 80mA 5 ms Muting Threshold Voltage (pin 3) Speech Operation 1 V MF Operation 1.6 V Muting Stand by Current (pin 3) IL = 12 to 80mA – 10 µA Muting Operating Current (pin 3) IL = 12 to 80mA, S2 in (b) + 10 µA LS256

SO20 PACKAGE MECHANICAL DATA DIM. mm inch A 2.65 0.104 a1 0.1 0.3 0.004 0.012 a2 2.45 0.096 b 0.35 0.49 0.014 0.019 b1 0.23 0.32 0.009 0.013 C 0.5 0.020 c1 45 ° (typ.) D 12.6 13.0 0.496 0.512 E 10 10.65 0.394 0.419 e 1.27 0.050 e3 11.43 0.450 F 7.4 7.6 0.291 0.299 L 0.5 1.27 0.020 0.050 M 0.75 0.030 S8 ° (max.) LS256

DIP16 PACKAGE MECHANICAL DATA DIM. mm inch a1 0.51 0.020 B 0.77 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.010 D 20 0.787 E 8.5 0.335 e 2.54 0.100 e3 17.78 0.700 F 7.1 0.280 I 5.1 0.201 L 3.3 0.130 Z 1.27 0.050 LS256

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequence s 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. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.  1996 SGS-THOMSON Microelectronics – Printed in Italy – All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands -Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. LS256