U3761MB
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A2, 23-Apr-97
1 (23)
Low Voltage Standard Telephone Circuit with 13 Memories
Description
TEMIC's low voltage telephone circuit, U3761MB
performs all the speech and line interface functions
required in an electronic telephone set, the tone ringer, the
pulse and DTMF dialing with redial, notice function, and
13 memories.
Features
Speech Circuit
D Adjustable DC characteristic
D Symmetrical input of microphone amplifier
D Receiving amplifier for dynamic or
piezo-electric earpieces
D Automatic line loss compensation
Dialer
D DTMF / pulse switchable
D Pulse dialling 66/33 or 60/40 or DTMF dialling
selectable by pin
D Selectable flashing duration by key pad
D Pause function
D Last number redial up to 32 digits
D Three by 32 digits direct (one touch) memory
D Ten by 16 digits indirect (two touch) memory
D Notice function up to 32 digits
D Standard low-cost crystal 3.57 MHz or
ceramic resonator
Tone Ringer
D 2 Tone ringer
D Adjustable volume
D RC oscillator
D Adjustable threshold
Benefits
D Low number of external components
D High quality through one IC solution
U3761MB
TELEFUNKEN Semiconductors
Rev. A2, 23-Apr-97
Preliminary Information
4 (23)
Pin Description
SDIP40
SSO44
Symbol
Configuration
Function
1
1
C1
C1
Keyboard input
2
2
C2
C1
PD
3
3
C3
C2C4
4
4
C4
PD
5
5
Earth
Earth key
15
7, 6,
34, 35
NC
Not connected
6
8
XT
XT
XT
PD
PD
40P
40P
A built-in inverter provides
oscillation with an inexpensive
3.579545 MHz crystal or ceramic
resonator
7
9
XT
XT
XT
PD
PD
40P
40P
8
10
MFO
MFO
Output of DTMF
DTMF output frequency
Specified
Actual
Error
(HZ)
(Hz)
(%)
R1
697
699
+0.28
R2
770
766
0.52
R3
852
848
0.47
R4
941
948
+0.74
C1
1209
1216
+0.57
C2
1336
1332
0.30
C3
1477
1472
0.34
9
12
GND
Ground
U3761MB
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A2, 23-Apr-97
5 (23)
Function
Configuration
Symbol
SSO44
SDIP40
10
13
MIC 1
MIC1
VI
VI
MIC2
1V
1V
PD
PD
50K
50K
Inverting input of microphone
amplifier
11
14
MIC 2
MIC1
VI
VI
MIC2
1V
1V
PD
PD
50K
50K
Non-inverting input of microphone
amplifier
12
15
MICO
VI
1V
MICO
PD
16K
Transmit pre-amp output which is
normally capacitively coupled to
Pin TIN
13
16
VL
VL
RDC
PD
PD
16V
Positive supply voltage input to the
device. The current through this
pin is modulated by the transmit
signal.
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