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TEMIC Semiconductors |
Tone Ringer Interface
U4074B
Description
The U4074B is a monolithic integrated circuit that
contains all integral components of a ringing circuit for
telephone sets used in conjunction with a microcomputer.
The combination of a microcomputer and the U4074B
permits flexible programming of the ringing sequence
( melody), tone and volume control.
Ringing frequency detection takes place in the
microcomputer. The U4074B is responsible for the
interface to the line, driver stages for the piezoelectric
sound transducer, volume adjustment, amplitude
detection, voltage supply for the microcomputer and
other auxiliary functions.
Features
D Suitable for specifications FTZ 1TR2 and ETR 2
D Rectifier bridge
D Z-diode
D Amplitude detection
vD Supply voltage for microcomputer 3.5 @ 1.5 mA
D DC operation possible
D Bridge push-pull output stage
D CMOS-compatible microcomputer interface
D 2-bit log. volume adjustment
D High-voltage bipolar technology, 30 V
Benefits
mD C controlled melody and volume
D Low number of external components
22mF
VB 2(3)
47mF
130 kW
TH 3(4) VDD 10 (12) 2f 4(5)
Ȁma 0.8 F (1)1 a
2.2 kW
Ringing signal
b (16)14
bȀ
Control
VRef
Decoder and
DA converter
On/Off
2f
+VB
12(14)
O2
+VB
PIEZO
O1 Transducer
11(13)
93 7793 e
(15)13 GND 5(6)
6(7) (9)7 Mel
VDC 8(10)
9(11)
A1 A0
Volume
Figure 1. Block diagram and application circuit ( pin connections for SO16 in brackets )
TELEFUNKEN Semiconductors
Rev. A1, 06-May-96
Preliminary Information
1 (6)
U4074B
Pin Configuration
aȀ 1
NC 2
VB 3
TH 4
2f 5
A1 6
A0 7
NC 8
16 bȀ
15 GND
14 O2
13
O1
12 VDD
11 VDC
10 VDC
9
94 7904 e
Mel
aȀ 1
VB 2
TH 3
2f 4
A1 5
A0 6
Mel 7
14 bȀ
13 GND
12 O2
11 O1
10 VDD
9 VDC
8 VDC
94 7903 e
Pin
1, 14
(1,16)
2 (3)
3 (4)
4 (5)
5, 6
(6, 7)
7 (9)
8, 9
(10, 11)
10 (12)
11, 12
(13, 14)
13 (15)
(2, 8)
Symbol
aȀ, bȀ
VB
TH
2f
A1, A0
Mel
VDC
VDD
O1, O2
GND
NC
Function
AC ringing signal input
Output to charging capacitor
Comparator threshold adjust-
ment input
Output for frequency detection
Digital volume adjustment in-
put
Input for melody signal
DC supply diode connections
Microcomputer supply voltage
Outputs to the transducer
Ground
Not connected
Pin Description
Power supply aȀ and bȀ, Pin 1, 14
An ac ringing voltage is supplied to the inputs aȀ and bȀ
via a 0.8 mF decoupling capacitor connected in series with
a 2.2 kΩ. resistor
3. The circuit possesses the following overload resis-
tance at terminals a and b.The circuit can withstand
a voltage of 110 V with a frequency of 50 Hz at
terminals a and b for a maximum of 15 s.
4. Testing the circuit with the configuration shown in
figure 2 does not destroy the circuit under the
following conditions.
Charging voltage of surge capacitance: Vcs = 2 kV
Pulse shape: 10/700 ms
Pulse sequence: 30 s
Number of surges: 10
Polarity change after 5 surges
See figure 2.
Smoothing Capacitors, Pin 2, 10
After rectification of the ac ringing voltage via the
integrated rectifier bridge, the pulsating DC voltage is
smoothed by the external capacitor ( 22 mF to 47 mF ) at
Pin 2 ( 3 ). The charging voltage is restricted to a
maximum of 30 V by an integrated Z-diode. A 47 mF
external capacitor of will smooth the regulated supply,
VDD, at pin 10 (12 ).
2 (6) TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 06-May-96
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