U4076B Datasheet, PDF (2/6 Pages) TEMIC Semiconductors – Three-Tone Ringer for Telephone Sets

U4076B
Pin Description
Pin
1 (1)
2, 3
(2, 3)
4 (5)
5, 7
(6, 8)
6 (7)
(8, 9,
10)
Symbol
Function
Frequency monitoring
Open: 23 to 54 Hz
Ground: 12 to 54 Hz
With Pin 6 (7) connected:
Switched off
Clock signal generator
Ground
Power supply
Charging capacitor, C_L, for
bridge rectifier
Frequency oscillator
Pin
8, 9,
10
(9, 10,
11)
11, 12
(12,
13)
13
(15)
14
(16)
(4,
14)
Symbol
Function
Tone sequence
Frequency oscillator
Output signals
Output signal shape
Open = short pulse width
Ground = 1:1
Load resistance, R_L
Not connected
Pin Connections and Functional
Description Including External
Circuitry
Pin 1: Frequency monitoring
Frequency is monitored via Pin 1. The following possibi-
lities are available (three-state logic):
a) Pin 1 is open: ringing frequency is between 23 and
54 Hz.
b) Pin 1 is grounded: ringing frequency is between 12
and 54 Hz.
c) Pin 1 is connected to Pin 6 (7): ringing frequency has
no influence (dc operation)
Pins 2 and 3 (2, 3): Clock signal generator
A ceramic resonator for a frequency of 455 kHz must be
connected between Pin 2 (2) and Pin 3 (3). The clock
frequency of the generator is used for three-tone ringing
sequence and control signals for frequency identification.
Pin 4 (5): Ground
Reference point for all voltages.
Pins 5, 6 and 7 (6, 7, 8): Power supply
Pins 5 (6) and 7 (8) connect the circuit with a ringing ac
m W ^{supplied by the exchange via lines a and b. A decoupling}
capacitor of 1 F in series with 2.2 k resistance is
needed for overvoltage protection and the insertion loss
requirement of the German Post Office specifications.
The supplied ac current is rectified by the on-chip bridge
circuit. The rectified current charges the capacitor on
Pin 6 (7), which supplies the dc voltage for the integrated
circuit. Instead of a ringing ac current supplied by the ex-
change, the IC can be driven by a dc voltage applied
directly to terminals 6 (7) (+) and 4 (5) (–). An integrated
Z diode limits the maximum supply voltage range up to
27 V.
Pins 8, 9 and 10 (9, 10, 11):
Sequence frequency adjustment
The sequence of the three-tone ringing frequency (800,
1067 and 1333 Hz) is determined by the external network
calculated as follow:
+ + _{W )} f₂
f_OSC
192
whereas f_OSC
(43 k
IC
R_V) 47 nF
 if: k 0.95 then R_v
 if: k 1 then R_v
 if: k 1.2 then R_v
= 0 to 20 kΩ
= 30 to 150 kΩ
> 200 kΩ
The sequence frequency adjustment is determined by the
frequency prescaler ratio in the IC.
Pins 11 and 12 (12, 13): Output signal
The three-tone ringing sequence of 800 Hz, 1067 Hz and
1333 Hz is realized if the clock oscillator is synchronised
with a ceramic resonator of 455 kHz between Pins 2 (2)
and Pin 3 (3). This gives excellent tone frequency and
eliminates complicated frequency setting procedures.
The output signal without load is (2 V₆₍₇₎ – 2.5) V_pp. The
output stage transducers in BTL configuration can pro-
cess an average current of up to 20 mA, whereas a short
time current of 40 mA is possible in both direction when
t = 0.1 ms. An external current limitation is necessary
when the IC is operating with voltage between Pin 6(7)
and Pin 4 (5). The tone sequence always starts at the
lower frequency.
2 (6)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 15-May-96