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LS256
TELEPHONE SPEECH CIRCUIT WITH MULTIFREQUENCY TONE GENERATOR INTERFACE
.PRESENTSTHEPROPERDCPATHFORTHE .HANDLES .ACTSASLI
LINE CURRENT 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 NEAR INTERFACE FOR MF, SUPPLYING A STABILIZEDTO THE DIGITAL CHIP AND DELIVERING TO THE LINE THE MF TONE GENERATED BY THE DIALER
DIP16 SO20
ORDERING NUMBERS : LS256B LS256D
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 PIN CONNECTIONS (top view)
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.
N.C. MIC. INPUT +LINE MUTING BIAS ADJ. SHUNT REG. BYPASS DC. REGULATOR LINE CURRENT SENSING GAIN CONTROL N.C.
1 2 3 4 5 6 7 8 9 10
D96TL274
20 19 18 17 16 15 14 13 12 11
N.C. MIC. INPUT VDD MF INPUT RECEIVER OUTPUT RECEIVER OUTPUT INPUT+(REC.AMP.) INPUT-(REC.AMP.) -LINE N.C.
SO20 DIP16
November 1996
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LS256
BLOCK DIAGRAM (ref. to DIP16)
ABSOLUTE MAXIMUM RATINGS
Symbol VL IL IL Ptot Top Tstg, Tj Forward Line Current Reverse Line Current Total Power Dissipation at Tamb = 70C Operating Temperature Storage and Junction Temperature Parameter Line Voltage (3ms pulse duration) Value 22 150 - 150 1 - 45 to 70 - 65 to 150 Unit V mA mA W C C
THERMAL DATA
Symbol Rth j-amb Parameter Thermal Resistance Junction-ambient Max DIP16 80 SO20 150 Unit C/W
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LS256
TEST CIRCUITS (ref. to DIP16)
Figure 1.
Figure 2.
V = 0,1V ; CMRR
Side tone =
VSO VRO ; Gs = VMI VMI
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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 VL CMRR GS Parameter Line Voltage Test Conditions IL IL IL f = 1kHz, IL = 12 to 80mA Tamb = 25C, f = 1kHz IL IL VMI = 2mV Tamb = 25C = 12mA = 20mA = 80mA = 52mA = 25mA Min. 3.9 Typ. Max. 4.7 5.5 12.2 45 49 46 50 1 2 10 -68.5 40 - 30 - 30 2.5 7 3.5 8 4.5 9 1 2 10 2 10 100 100 Unit V Fig. SPEECH OPERATION
Common Mode Rejection Sending Gain
50 44 48
dB dB
1 2
Sending Gain Flatness Sending Distortion Sending Noise Microphone Input Impedance Pin 1-16 Sending Loss in MF Operation Receiving Gain
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 = 25C 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
dB % dBmp k dB dB
2 2 2
2 3
GR
Receiving Gain Flatness Receiving Distortion
dB %
3 3
Receiving Noise Receiver Output Impedance Pin 12-13 4/8
V
3
LS256
ELECTRICAL CHARACTERISTICS (continued)
Symbol GR ZML Sidetone Parameter Test Conditions F = 1kHz, Tamb = 25C, S1 in (b) IL = 52mA IL = 25mA VRI = 0.3V, f = 1kHz IL = 12 to 80mA IL = 12 to 80mA 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) Min. Typ. Max. Unit Fig. dB 36 36 700 2 SPEECH OPERATION (continued)
Line Matching Impedance
500
600
MULTIFREQUENCY SYNTHESIZER INTERFACE VDD IDD 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) 2.4 2.5 V
0.5 2 15 3VDD 40
17
mA mA dB V k % ms V V A A
4
VI RI d
2 5 1 1.6 - 10 + 10
4
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LS256
SO20 PACKAGE MECHANICAL DATA
DIM. MIN. A a1 a2 b b1 C c1 D E e e3 F L M S 7.4 0.5 12.6 10 1.27 11.43 7.6 1.27 0.75 8 (max.) 0.291 0.020 13.0 10.65 0.35 0.23 0.5 45 (typ.) 0.496 0.394 0.050 0.450 0.299 0.050 0.030 0.512 0.419 0.1 mm TYP. MAX. 2.65 0.3 2.45 0.49 0.32 0.014 0.009 0.020 0.004 MIN. inch TYP. MAX. 0.104 0.012 0.096 0.019 0.013
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LS256
DIP16 PACKAGE MECHANICAL DATA
DIM. MIN. a1 B b b1 D E e e3 F I L Z 3.3 1.27 8.5 2.54 17.78 7.1 5.1 0.130 0.050 0.51 0.77 0.5 0.25 20 0.335 0.100 0.700 0.280 0.201 1.65 mm TYP. MAX. MIN. 0.020 0.030 0.020 0.010 0.787 0.065 inch TYP. MAX.
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LS256
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequence of use of such information nor for any infringement of patents or other rig hts of third parties which may result from its s 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. (c) 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.
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