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TELEFUNKEN Semiconductors
U4078B
Tone Ringer Interface with DC/DC Converter
Description
The tone ringer interface with dc/dc converter U4078B is an integrated circuit realized in bipolar technology, which allows high efficient power transfer. Galvanic separation takes place at Pin 5 either with inductive or opto-coupler mode.
Features
D Suitable for the specification:
FTZ, 1TR2 and ETR2
Benefits
D High efficient power transfer
D D D D
Rectifier bridge Z-diode Amplitude detection Detection of ringing signal i.e., sine-, triangle-, or rectangular (tone ringing) signal
D High-voltage bipolar technology D Compact surface mount package (SO8)
22 mF VB 1.5 kW 1 2 Hysteresis and power supply 8 7 GND 3 TH 47 pF
92 7460 e
output
b 1
a
a b
38 kHz
Pulse 5 shaping ST
mC supply
2f
mF
6 OSC 180 kW
4 MS
Figure 1. Block diagram with external circuit
14.04.94
1
U4078B
Pin Description
Pin 1, 8 2 3 4 5 6 7 Symbol a ,b VB TH MS ST OSC GND Function AC ringing signal input Output to charging capacitor (for supply) Comparator threshold adjustment input Mode selection: inductive or opto-coupler mode Switching transistor connection RC circuit for internal oscillator input Ground a' 1
TELEFUNKEN Semiconductors
8
b'
VB
2
7
GND
U4078B
TH 3 6 OSC
MS
4
94 7902 e
5
ST
Functional Description
The ringing ac signal, supplied by the exchange via lines a, b, is identified by a comparator circuit. An integrated oscillator, generates a 38 kHz clock signal, fclock, via a coupled 2:1 divider. With the help of the external RC circuit, oscillation frequency is set at Pin 6. A PNP-transistor connected at Pin 5 enables the power transmission (transfer) in inductive or opto-coupler mode, which is selected at Pin 4. For inductive mode, Pin 4 is open, whereas for opto-coupler mode, Pin 4 is connected to GND (Pin 7). bridge circuit, the smoothing of the power supply is provided by the external capacitance at Pin 2 ( 22 nF ).
Pin 3: Comparator Threshold
* TH
Comparator threshold*as regards the ringing voltage* is set at ca. 12.5 V. Switching threshold can be increased or decreased by connecting a resistance at Pin 3 w.r.t. GND.
Pin 4: Mode Selection
* MS
Pin 1,8: Power Supply - a , b
Pins 1 and 8 connect the circuit with the ac ringing signal supplied by the exchange via lines a and b. A 1F decoupling capacitor of 1 F value together with a series resistance (1.5 k) protect the circuit from overload across Pins 1 and 8. The circuit features the following overload protection across the a , b terminals: 1) It can withstand a voltage of 110 V @ 50 Hz for maximum time of 15 seconds. 2) Testing of the circuit according to figure 2 does not destroy the circuit under following conditions: Charging voltage of surge capacitance: VCS = 2 kV Pulse shape: 10/700 s Pulse sequence: 30 s No. of surges: 10 Polarity change after 5 surges
The ringing ac signal transfer (transmission) without potential loss occurs either via an inductive or opto-coupler mode. Pin 4 is set to a high state by an internal power source of 4 A (approximately). This switches the output (Pin 5) to an operating state for the inductive mode. In case of opto-coupler mode, Pin 4 is connected to the ground (Pin 7).
Pin 5: Switching Transistor Connection
An external PNP transistor, whose emitter is at VS (Pin 2) potential, serves to control the inductive or opto-coupler mode by connecting the base of the transistor with Pin 5. In case of inductive mode, the signal, fclock is interrupted for the duration of tpulse = 32/fclock, with every transition (rise or fall) of the ringing ac signal, fring. During the interruption, the setting at Pin 5 is such that the coil is critically damped (attenuated), whereas a current of 10 A flows when the transistor at Pin 5 is switched on during the following tpulse up to the next edge of the pulse. In case of opto-coupler mode, the external transistor is switched on for a period of tpulse = 32/fclock with every flank of the pulse of fring. Pin 5 is at high resistance upto the next edge (flank) of the transition pulse of the ringing ac signal.
Pin 2: Charging Capacitor (power supply filtering)
After the rectification of the ringing ac signal across the
2
TELEFUNKEN Semiconductors
U4078B
15 W 25 W a 110W 0.22 mF Tone ringing Figure 1 b
93 7575 e
2 kV
10 mF
Figure 2
Absolute Maximum Ratings
Reference point Pin 7, unless otherwise specified Parameters Supply current Pin 1, 8 Ambient temperature range Symbol Is Tamb Value 50 - 10 to + 60 Unit mA
Storage temperature range Power dissipation Tamb = 60C Junction temperature
Tstg Ptot Tj
-40 to + 125
360 125
C C
mW
C
Thermal Resistance
Parameters Junction ambient Symbol
RthJA
Value 180
Unit K/W
Electrical Characteristics
Reference point Pin 7, Tamb = - 10 to + 60C, VB = 15 V, unless otherwise specified Parameters Supply current Test Conditions / Pin Symbol Min Typ 420 10 200 26 100 150 7 32.5 0.67 10 38 1 32/fclock 3 13 48.5 30 32 12.5 Max 500 15 Unit
fosc = 65 to 87 kHz
Pin 1, 8
Is VTH
A
V
Threshold voltage for slope identification
Audio impedance
Pin 3 open f = 300 to 3400 Hz V1,8 = 1@5 Vrms Iz = 1 mA 1. phase 2. phase
R
k
V
Internal voltage limitation Leakage current Base current (PNP open) Oscillator frequency range Duty-cycle Interrupted (pause) time of the output signal Pin 5 Pin 5 Pin 6
Pin 6
Vz i5 i5 IB(5) fosc
A
kHz
U4078B
Time Sequence
Internal clock frequency without RC tolerance
tclock tpulse During this time, a clock signal is given at Pin 5 (ST).Pin 4 is open or ST is high ohmic. (MS=GND) By every polarity change of the call signal and MS open, the clock signal is interrupted for a time duration
TELEFUNKEN Semiconductors
tpulse = 32/fclock. During interruption, the signal at ST (Pin5) is of such a value that the coil is critically attenuated (damped). IS (PNP) = IST 10 A 150 A is drawn from Pin 5 (ST) by A current of IST every polarity change whereby MS is grounded.
[ x
Call signal
ST MS = 0
92 7461 e
Current sequence at Pin 5 with an external PNP transistor connected as shown in figure 1. (fclock = 38 kHz)
Ordering Information
Package SO8 Type U4078B-FP
Dimensions in mm
Package: SO8
4
EEEEEEEEEEEE EE EEEE E EEEEEEEEEEEE EE EEEE E
tcycle tpuls
e
ST MS = open
ST 1. Phase 1 fcycle 2. Phase t
92 7471 e
t
TELEFUNKEN Semiconductors
U4078B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances ( ODSs). The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency ( EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively. TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances.
We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423
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