LS356B ,Telephone Speech Circuit With Multifrequency Tone Generator Interface‘— SGSmiiltmlS0hl
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TELEPHONE SPEECH CIRCUIT WITH MULTIFREQUENCY
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LS356B
Telephone Speech Circuit With Multifrequency Tone Generator Interface
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717 MH©§©ELE®WE©M©$ LS356
TELEPHONE SPEECH CIRCUIT WITH MULTIFREQUENCY
TONE GENERATOR INTERFACE
u PRESENTS THE PROPER DC PATH FOR THE
LINE CURRENT
I: HANDLES THE VOICE SIGNAL, PERFOR-
MING THE 2/4 WIRES INTERFACE AND
CHANGING THE GAIN ON BOTH SENDING
AND RECEIVING AMPLIFIERS TO COMPEN-
SATE FOR LINE ATTENUATION BY SENSING
EITHER THE LINE CURRENT OR THE LINE
VOLTAGE. IN ADDITION, THE LS356 CAN AL-
SO WORK IN FIXED GAIN MODE
u ACTS AS LINEAR INTERFACE FOR MF, SUP-
PLYING A STABILIZED VOLTAGE TO THE Dl-
GITAL CHIP AND DELIVERING TO THE LINE
THE MF TONES GENERATED BY THE M761
DESCRIPTION
The LS356 is a monolithic circuit in 16-Iead dual in-
line plastic package to replace the hybrid circuit in
telephone set. It works with the same type of trans-
ducers for both transmitter and receiver (typical dy-
BLOCK DIAGRAM
ORDER CODES I LS356B
LS356AB
namic capsules, but the device can also work with
piezoceramic ones). Many of its electrical charac-
teristics can be controlled by means of external com-
ponents to meet different specifications.
In addition to the speech operation, the LS356 acts
as an interface for the MF tone signal (particularly
for M761 C/MOS frequency synthesizer).
S‘LBJDH J.
November 1988
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
VL Line Voltage (3 ms pulse duration) 22 V
IL Forward Line Current 150 mA
IL Reverse Line Current - 150 mA
Ptot Total Power Dissipation at Tamb = 70 °C 1 W
Top Operating Temperature - 45 to 70 °C
Tstg, Ti Storage and Junction Temperature - 65 to 150 “’0
PIN CONNECTION (top view)
MICJNPUT t 1 t6 ] MICJNPUT
.LINE [2 15] V00
MUTING £3 1:.) MFINPUT
BIAS ADJ. [a 13] RECEIVER OUTPUT
grggsREG' is 12] RECEIVER OUTPUT
D.CREGULATOR ( 6 11 ] INPUTotREC.AMP)
LINE CURRENT
SENSING 7 10] lNPUT-(RECAMF)
GAIN CONTROL its 9 J -LiNE
THERMAL DATA
Rm j-amb Thermal Resistance Junction-ambient Max 80 °C/W
2/14 tFi' scs-monsom
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