LS256 TELEPHONE SPEECH CIRCUIT WITH MULTIFREQUENCY TONE GENERATOR INTERFACE . . . PRESENTS THE PROPER DC PATH FOR THE LINE CURRENT HANDLES THE VOICE SIGNAL, PERFORMING THE 2/4 WIRES INTERFACE AND CHANGING THE GAIN ON BOTH SENDING AND RECEIVING AMPLIFIERS TO COMPENSATE FOR LINE ATTENUATION BY SENSING THELINE LENGTHTHROUGH THE LINE CURRENT ACTS AS LINEAR INTERFACE FOR MF, SUPPLYING A STABILIZEDTO THE DIGITAL CHIP AND DELIVERING TO THE LINE THE MF TONE GENERATED BY THE DIALER SO20 DIP16 ORDERING NUMBERS : LS256B DESCRIPTION The LS256 is a monolithic integrated circuit in 16lead dual in-line and SO20 plastic packages to replacethe hybridcircuit in telephoneset.It workswith the same type of transdurcers for both transmitter and receiver (typically piezoceramic capsules, but LS256D the device can 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) N.C. 1 20 N.C. MIC. INPUT 2 19 MIC. INPUT +LINE 3 18 VDD MUTING 4 17 MF INPUT BIAS ADJ. 5 16 RECEIVER OUTPUT SHUNT REG. BYPASS 6 15 RECEIVER OUTPUT DC. REGULATOR 7 14 INPUT+(REC.AMP.) LINE CURRENT SENSING 8 13 INPUT-(REC.AMP.) GAIN CONTROL 9 12 -LINE 11 N.C. N.C. 10 D96TL274 SO20 DIP16 November 1996 1/8 LS256 BLOCK DIAGRAM (ref. to DIP16) ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VL Line Voltage (3ms pulse duration) 22 V IL Forward Line Current 150 mA IL Reverse Line Current – 150 mA 1 W Ptot Total Power Dissipation at Tamb = 70°C Top Operating Temperature – 45 to 70 °C Storage and Junction Temperature – 65 to 150 °C Tstg, Tj THERMAL DATA Symbol Rth j-amb 2/8 Parameter Thermal Resistance Junction-ambient Max DIP16 SO20 Unit 80 150 °C/W LS256 TEST CIRCUITS (ref. to DIP16) Figure 1. V = 0,1V ; CMRR Figure 2. Side tone = VSO VRO ; Gs = VMI VMI 3/8 LS256 Figure 3. Figure 4. GR = VRO VRI GMF = VMO VMF ELECTRICAL CHARACTERISTICS (refer to the test circuits, S1, S2 in (a), Tamb = – 25 to + 50oC, f = 200 to 3400Hz, unless otherwise specified) Symbol Parameter Test Conditions Min. Typ. Max. Unit 4.7 5.5 12.2 V Fig. SPEECH OPERATION VL CMRR GS Line Voltage Common Mode Rejection Sending Gain Sending Gain Flatness Sending Distortion GR Sending Noise Microphone Input Impedance Pin 1-16 Sending Loss in MF Operation Receiving Gain Receiving Gain Flatness Receiving Distortion Receiving Noise Receiver Output Impedance Pin 12-13 4/8 Tamb = 25°C IL IL IL f = 1kHz, IL = 12 to 80mA Tamb = 25°C, f = 1kHz IL IL VMI = 2mV = 12mA = 20mA = 80mA = 52mA = 25mA VMI = 2mV, fref = 1kHz IL = 12 to 80mA f = 1kHz VSO = 1V VSO = 1.3V IL = 16 to 80mA VMI = 0V; IL = 40mA; S1 in (b) VMI = 2mV, IL = 12 to 80mA IL = 52mA VMI = 2mV IL = 25mA S2 in (b) VR1 = 0.3V, f = 1kHz, Tamb = 25°C IL = 52mA IL = 25mA VRI = 0.3V, fref = 1kHz IL = 12 to 80mA f = 1kHz IL = 12mA VRO = 1.6V IL = 12mA VRO = 1.9V IL = 50mA VRO = 1.8V IL = 50mA VRO = 2.1V VRI = 0V; IL = 12 to 80mA; S1 in (b) VRO = 50mV, IL = 40mA 3.9 50 44 48 45 49 dB dB 1 2 ±1 dB 2 2 10 –68.5 % 2 dBmp kΩ 2 dB 2 dB 3 dB 3 % 3 µV Ω 3 46 50 40 – 30 – 30 2.5 7 3.5 8 4.5 9 ±1 2 10 2 10 100 100 LS256 ELECTRICAL CHARACTERISTICS (continued) Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig. SPEECH OPERATION (continued) GR ZML Sidetone Line Matching Impedance F = 1kHz, Tamb = 25°C, S1 in (b) IL = 52mA IL = 25mA VRI = 0.3V, f = 1kHz IL = 12 to 80mA dB 500 600 IL = 12 to 80mA 2.4 2.5 IL = 12 to 80mA IL = 12 to 80mA ; S2 in (b) IL = 12 to 80mA, fMF in = 1kHz VMF in = 80mV VM Fin = 80mV VM Fin = 80mV VM Fin = 110mV IL = 12 to 80mA IL = 12 to 80mA Speech Operation MF Operation IL = 12 to 80mA IL = 12 to 80mA, S2 in (b) 0.5 2 15 36 36 700 2 Ω MULTIFREQUENCY SYNTHESIZER INTERFACE VDD IDD VI RI d MF Supply Voltage (standby and operation) MF Supply Current Stand by Operation MF Amplifier Gain DC Input Voltage Level (pin 14) Input Impedance (pin 14) Distortion Starting Delay Time Muting Threshold Voltage (pin 3) Muting Stand by Current (pin 3) Muting Operating Current (pin 3) V 17 mA mA dB 4 2 V kΩ % 4 3VDD 40 5 1 1.6 – 10 + 10 ms V V µA µA 5/8 LS256 SO20 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. A a1 inch MAX. TYP. 2.65 0.1 MAX. 0.104 0.3 a2 0.004 0.012 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 S 6/8 MIN. 0.75 0.030 8° (max.) LS256 DIP16 PACKAGE MECHANICAL DATA mm DIM. MIN. a1 0.51 B 0.77 TYP. inch MAX. MIN. TYP. MAX. 0.020 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 Z 3.3 0.130 1.27 0.050 7/8 LS256 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 rig hts 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. 8/8