U4030B
Telephone Speech Circuit
Description
The U4030B is an electronic speech circuit for standard
and feature telephones. It replaces the hybrid transformer,
earphone and microphone interface and the supply
voltage generation for external components, e.g. dialer or
microcomputers. Using the U4030B in telephone circuit
designs can improve transmission quality and results in
cost savings through shorter and more flexible design
procedures. It reduces the amount of external components
needed. The U4030B uses TEMIC’s reliable bipolar
technology and is offered in a SO20 package.
Features
Benefits
D Microphone amplifier with
D Independent adjustment of
– Transmission gain
– Receiving gain
– Sidetone suppression
– Frequency response
– Symmetrical input
– Privacy function
– Anticlipping
D Built in ear protection
D Power down input
D Low-impedance supply voltage for all external blocks
D Supply voltage for an electret microphone
D Mute input
Applications
D
D
D
D
D DTMF interface
D Low line impedance during pulse dialing
Standard telephone
Fax machine
Answering machine
Cordless telephone
Block Diagram
GT
MICO
DTMF
PRIV
10
GR
5
6
RECO
7
–
+
+
–
–
+
16
ST
9
11
Ear protection
12
MIC1
MIC2
TXA
13
Limiter
Power supply
U 4030 B
Mute
3
CLIM
8
MUTE
17
PD
4
CK
15
VL
19
RDC
REC.ATT.
14
18
GND
SWAMP
2
1
VM
VC
20
VD
93 7618 e
Figure 1.
Ordering Information
Extended Type Number
U4030B-AFL
U4030B-AFLG3
Rev. A2, 27-Jan-98
Package
SO20
SO20
Remarks
Taped and reeled
1 (14)
U4030B
Pin Description
VM
1
20
VD
VC
2
19
RDC
CLIM
3
18
SWAMP
Pin
10
CK
4
17
PD
11
12
ST
5
16
PRIVACY
13
GR
6
15
VL
14
RECO
7
14
GND
15
16
MUTE
8
13
MIC2
MICO
9
12
MIC1
DTMF
10
11
GT
17
18
95
Pin
1
Symbol
VM
2
VC
3
CLIM
4
5
CK
ST
6
7
8
GR
RECO
MUTE
9
MICO
2 (14)
Function
Supply voltage for an elecret
microphone, virtual ground
The internal inductance of the
circuit is proportional to the
value of the capacitor at this pin.
A resistor connected to ground
may be used to reduce the line
voltage
Time constant of anticlipping in
trans. path
Input of receive amplifier
Input of sidetone amplifier, must
be DC-coupled to VM
Input for receive gain control
Output of receiving amplifier
Active high input to switch
circuit in DTMF-condition
Output of microphone amplifier
19
20
Symbol
DTMF
Function
Input for DTMF signals (ACcoupled). In mute condition a
small portion of the signal at this
pin is monitored to the receive
output
GT
Input for transmit gain control
MIC1
Inverting input of microphone
amplifier
MIC2
Non-inverting input of
microphone amplifier
GND
Ground (reference point for DC
and AC signals)
VL
Line voltage
PRIVACY Active high input to disable
microphone amplifier
PD
Power down input. Active high
input for reducing the current
consumption of the
circuit. Simultaneously VL is
shorted by an internal switch
SWAMP A resistor connected from this
point to ground converts the
excess line current into heat in
order to prevent the IC from
thermal destruction at high line
currents
RDC
Input of power supply
VD
Unregulated supply voltage for
peripheral circuits. Output
current capability and output
voltage increase with line current
Rev. A2, 27-Jan-98
U4030B
Circuit Description
Reference for all descriptions is figure 9, unless otherwise
specified.
300 W and the maximum output current is 300 mA. The
VM-pin is virtual ground for the receiving amplifier.
Power Supply
6
DC characteristic
16
IL = 50 mA
Supply voltage VD ( V )
The power supply stage determines the voltage/ current
characteristic of the circuit. The DC-slope is adjusted to
100 W. A resistor connected from Pin 2 to Pin 14 may be
used to reduce the line voltage ( figure 2 ).
24 mA
19 mA
2
V (MIC) = 10 mVeff
12
VL ( V )
4
0
0
RC = ∞
8
12
16
20
Supply current ID ( mA )
93 7620 e
8
4
RC = 100 kW
Figure 3. Supply voltage, VD
4
0
20
40
60
80
100
IL ( mA )
93 7619 e
Figure 2. DC characteristics
VL = ( 0.0033
IRDC RDC
with:
IOFFSET
VRS
R30
IDC
IDC + IOFFSET )
( R30 || RC) + VRS+
Supply voltage for an
electret microphone ( V )
RDC = 10 kW
0
2
1
0
= 150 mA
= 150 mV
= 30 kW
= IL - ( 750 mA + 0.023
3
VD
An unregulated voltage, VD, is generated to supply the
internal and external circuits. The maximum voltage at
this pin is limited by an internal Z-diode to a value of
6.2 V. The available output current is shown in figure 3.
VM
The supply voltage for an electret microphone is derived
from VD (see figure 4). The output resistance is set to
Rev. A2, 27-Jan-98
5
6
Supply voltage VD ( mA )
93 7621 e
IL )
4
Figure 4. Electret microphone supply, VM
Swamp
Line current which is not used for internal and external
circuits is converted into heat via resistance Rswamp in
order to prevent the IC from thermal destruction at high
line currents.
The speech circuit will be high ohmic when the voltage
at SWAMP reaches 6 V. Typical characteristics for
various resistors are shown in figure 5.
3 (14)
U4030B
Electronic Inductance
20
Rswamp = 82
68
47
Line voltage VL ( V )
15
The AC resistance ( Rimp 1 kW ) of the telephone should
be much higher than the DC resistance ( 325 W ), the latter
being decoupled via an electronic inductance.
The value of L is given by:
10
L
= CVC
RDC
30 kW || R
where
5
RDC = 10 kW
0
0
20
40
60
80
100
120
Line current IL ( mA )
93 7622 e
Figure 5. Typical DC characteristics for various
SWAMP resistors
RDC
CVC
R30
RC
L
= 10 W
= 10 mF
= 30 kW
= infinite
=3H
Transmit
Microphone amplifier
Charge Up Circuit
By OFF HOOK the handset, an integrated charge up
circuit provides VD with the whole line current. When VD
reaches 2.2 V, the charge up circuit is automatically
switched off.
The specifications for the German “Deutsche Telekom”
(speech readiness, start time) will be fulfilled even with
1000 mF at Pin 20.
Figure 6 illustrates the transient behavior of the circuit at
IL = 20 mA.
VL
GT
= VMICO / V ( MIC1, MIC2 )
= 20 log [ (RS1 / RS2 ) + 1 ] dB
A low pass function can be realised with CSLP. The
corner frequency is given by:
fC
= 1 / ( 2 p RS1 CSLP )
When the AC level on VL is very high, the amplification
of the microphone is reduced by the limiter function. The
threshold of the limiter is fixed at 5.5 dBm ( typical).
DTMF
charge-up
1 V / div
The microphone amplifier of U4030B has symmetrical
inputs ( MIC1 and MIC2 ) with an input resistance of
60 kW ( typical). It has a gain of 29 dB which is adjustable
with resistances RS1 and RS2 as follows:
The amplification of the DTMF signal is determined by
the ratio of RS1 and RS2 as follows:
off
VD
GD = VMICO / VDTMF
= 20 log {0.19
[ ( RS1 / RS2 ) + 1 ] }
An external voltage divider is used to adjust the proper
DTMF level at line.
93 7623 e
time: 50 ms / div
Figure 6. Charge up characteristics at IL = 20 mA
4 (14)
For monitoring the dialing procedure, an attenuated
DTMF signal is sent to the earpiece. The Deutsche Telekom specification is fulfilled with the nominal value of
the transmit and receive gain.
Rev. A2, 27-Jan-98
U4030B
Transmit Output Amplifier
Sidetone
The output signal of the microphone and DTMF
preamplifier is internally coupled to a second amplifier
( TXA) which is used to modulate a controlled current
source. Assuming a termination of 600 W at a line, the
gain from MICO to VL is typically 15.6 dB.
The amplified microphone signal is available at the input
of the sidetone loop, MICO. The loop consists of a
transmit amplifier ( transconductance STX ), the
impedance at line, receive attenuator ( gain) and the sidetone network ( figure 7 ).
Receive Amplifier
The receive signal is taken from line via capacitor CCK.
A resistive attenuator ( –32 dB ) sets the appropriate input
level for the following output amplifier. The input
impedance at Pin 4 is typically 80 kW.
Voltage gain is:
GR
The sidetone cancellation is achieved by comparing a part
of the line signal with the output of the sidetone network
( VST → VR). Assuming a real impedance of the telephone ( RTel ) the optimum sidetone network can be
calculated:
a
= ( STX RAPP
ZNW = STX R G
G ) / ( 1 – STX
ZLine
RAPP
G)
Adjustment to the sensitivities of the handset can be done
independently from the sidetone network because receive
and transmit gain are set outside of the sidetone loop.
= 20 log ( Vear / VL ) dB
= –32 dB + 20 log [ ( RR1 / RR2 ) + 1 ] dB
= +1.8 dB
Power Down (PD)
The adjustment range for receive gain GR is typically
–4 dB to + 8 dB.
The built-in ear protection limits the output swing at Pin
7 to 2.4 Vpp ( VD > 4 V). For high receive gain, the
maximum undistorted output level might not be sufficient
due to clipping by ear protection.
The speech circuit is switched low ohmic by selecting a
high level at PD during the pulse dialling. The voltage
drop across the IC will be typically 1.5 V. During this time
the capacitor CVD will not be discharged, because an
internal power down switches off all internal amplifiers.
In order to avoid cracks, it is recommended to activate
power down while sending the dial pulses ( figure 8 ).
R
aR
ZNW
+
–
V ST
VH
VR
MICO
G = 1/40
Mic.
VL
STX = 18.8 mS
RTEL
ZL
93 7624 e
Figure 7. Schematic of the sidetone
Rev. A2, 27-Jan-98
5 (14)
U4030B
PD
VL
Pulse
“2”
“4”
93 7625 e
Figure 8. Recommended timing diagram for power down diagram
Absolute Maximum Ratings
Parameters
Line current (according to figure 9)
DC line voltage
Storage temperature range
Junction temperature
Ambient temperature range
Power dissipation
SO20
Tamb = 60_C
Symbol
IL
VL
Tstg
Tj
Tamb
Value
200
16
– 55 to +150
150
– 25 to + 65
Unit
mA
V
°C
°C
°C
Ptot
640
mW
Symbol
Value
Unit
RthJA
140
K/W
Thermal Resistance
Parameters
Junction ambient
SO20
6 (14)
Rev. A2, 27-Jan-98
U4030B
Electrical Characteristics
f = 1000 Hz, Tamb = 25_C, reference point Pin 14, unless otherwise specified
Parameters
Test Conditions / Pins
DC characteristics (figure 9)
DC voltage in speech mode IL = 19 mA
IL = 26 mA
IL = 60 mA
Transmit amplifier and sidetone reduction (figure 10)
Input resistance
Transmit gain
IL = 24 mA
Gain variation
19 mA
IL
60 mA
Noise at line,
RL = 600 W
psophometrically weighted ZRECO = 68 nF
ZMIC = 68 nF
IL = 19 to 60 mA
Sidetone gain (figure 10)
Max. output voltage
RL →
d 5%
VMIC = 5.4 mV
Common mode rejection
ratio
Mute: reduction of
ZRECO = 68 nF
voltage amplification
Privacy: reduction of
voltage amplification
Receiving amplifier (figure 11)
Gain
ZRECO = 68 nF
IL = 24 mA
Gain variation
19 mA
IL 60 mA
Noise at earphone
IL = 19 to 60 mA
psophometrically weighted Load T, R = 600 W
ZRECO = 68 nF
ZMIC = 68 nF
Max. output voltage
IL = 19 to 60 mA
ZRECO = 68 nF
d 2%
Switching threshold of ear
IL = 19 to 60 mA
protection
ZRECO = 68 nF
VGEN = 3 Vrms
Voltage amp. from
Zear = 68 nF
DTMF to RECO
Output impedance
Power down (figure 12)
PD-off input voltage
PD-on input voltage
Input current
VI = 6 V
Line voltage
PD on, IL = 24 mA
Input current consumption
PD on
at VD
x
x
R
x x
x
Symbol
Min.
Typ.
Max.
Unit
VL
6.2
6.5
7.2
10.5
6.8
11.0
V
V
V
80.0
45.2
+0.5
kW
dB
dB
– 75.0
dBmp
6.3
dB
dBm
10.0
RI
GT
DGT
60.0
44.7
nO
GST
VOmax
33.5
5.5
CMRR
80.0
dB
60.0
dB
– 3.9
DGR
– 0.5
– 3.4
nI
VOmax
600
–7
– 2.9
dB
0.5
– 78
dB
dBmp
650
0.7
VI
VI
II
VL
ID
dB
60.0
GR
x
Rev. A2, 27-Jan-98
45.0
44.2
– 0.5
–4
mVrms
1.3
Vrms
–1
dB
10
W
0.3
2
130
1.5
100
V
V
mA
V
mA
7 (14)
U4030B
Parameters
Mute input, (figure 12)
MUTE input current
Test Conditions / Pins
VMUTE = 6 V
VMUTE = 0.3 V
MUTE-off input voltage
MUTE-on input voltage
Supply voltages (figure 10)
Output voltage
IL = 19 mA
ID = 4.5 mA
VMIC = 10 mV
IL = 50 mA
ID = 15 mA
VMIC = 10 mV
Output voltage
IL = 19 mA
ID = 3 mA
IM = 300 mA
Output current
Output resistance
DTMF-amplifier (figure 12)
Input resistance
DTMF-gain
Load = ZR
0 < Rv < 1530 W
Max. output voltage
IL = 19 to 60 mA
Load = ZR
d 2%
Privacy (figure 12)
PRIV-on input voltage
PRIV-off input voltage
Input current
VPRIV = 6 V
Symbol
Min.
Typ.
IMUTE
120
– 25
0.3
VMUTE
VMUTE
1.5
VD
4.0
4.5
VM
2.2
IM
RO
31
26
mA
mA
V
V
V
V
300
mA
W
37
27
kW
dB
300
22
24.7
Unit
V
6.2
5.5
RD
GD
Max.
1.8
Vrms
x
8 (14)
VPRIV
VPRIV
IPRIV
2
0.8
60
V
V
mA
Rev. A2, 27-Jan-98
Rev. A2, 27-Jan-98
CK
68n
VC
10 m
CVM
U 4030 B
10 m
CLIM
VM
VD
VC
RDC
CLIM
470 n
RR2
CR
2.2 m
RR1
680
Figure 9. Application Circuit
33 k
R4
12 k
CRNW2
RNW2
100 n
18 k
1000 m
10
SWAMP
CK
PD
ST
PRIV
GR
VL
RECO
GND
MUTE
MIC 2
MICO
MIC 1
DTMF
GS
68
1k
15V
47 m
RNW3 CRNW3
2.7 k 100 n
RNW4
390
600
ID
100 m
12k
10 m
430
150
CRNW4
VL
68n
470 n
2.2 m
53n
MIC1
MIC2
93 7626 e
9 (14)
U4030B
DTMF
U4030B
10 (14)
ID
CK
IVM
68 n
VC
10 m
CVM
U 4030 B
VM
VC
10 m
CLIM
470 n
CR
PR 2
Figure 10. Transmit gain
2.2 m
680
33 k
R4
12 k
CRNW 2
100 n
PR 1
RNW 2
RNW 3
18 k
2.7 k
CLIM
ST
PRIV
GR
VL
RECO
GND
MUTE
MIC 2
MICO
MIC 1
DTMF
GS
CRNW4
68
VPRIV
RIMP
15 V
12 k
100 n
CRECO
RS2
430
ROUT
150
53 n
VMUTE
CS
DTMF
2.2 m
ZEAR
470 n
68 n
93 7627 e
Rev. A2, 27-Jan-98
DTMF
MIC 1
ZM
68 n
MIC 2
VMIC
RL
1k
68 n
RS 1
10 m
RNW 4
390
RSWAMP
SWAMP
PD
1000 m
10
RDC
CK
CRNW 3
CVD
VD
47 m
600
VL
100 m
IL
Rev. A2, 27-Jan-98
VC
DTMF
10m
470 n
CK
68 n
CVM
U 4030 B
10m
CLIM
VM
VD
VC
RDC
CVD
RDC
10
CLIM SWAMP
Figure 11. Receiving gain and sidetone amplification
470 n
CR
RR2
2.2 m 680
CK
PD
ST
PRIV
GR
RR1
1000 m
RSWAMP
68
VL
RECO
GND
MUTE
MIC2
MICO
MIC1
DTMF
CS
33 k
CRNW2
100 n
C
RNW2
18 k
RNW3
CRNW3
RS1
2.7 k
100 n
12 k
CRECO
10 m
RNW4
390
470 n
100 m
15 V
IL
68 n
47 m
VGEN
RS2
430
ROUT
150
CRNW4
VGEN
RIMP
1k
RL
600
CS
2.2 m
53 n
ZEAR
VEAR
68 n
ZM
MIC2
MIC1
68 n
U4030B
93 7628 e
11 (14)
U4030B
12 (14)
ID
VDTMF
VC
AC
10m
470 n
CK
68 n
CVM
10m
VM
VD
VC
RDC
CLIM
RSWAMP
Figure 12. DTMF gain
CR
PR2
2.2 m
680
33 k
R4
12 k
CRNW2
RNW2
RNW3
18 k
2.7 k
PD
ST
PRIV
GR
PR1
IPD
GND
MUTE
MIC2
MICO
MIC1
DTMF
GS
CRNW3
RS1
100 n
12 k
1.5 n
IMUTE
68 n
CRNW4
RS2
100 n
ZEAR
93 7629 e
Rev. A2, 27-Jan-98
68 n
VMUTE
RIMP
1k
ZR
47 m
100 m
IL
68 n
ZM
ROUT
150
VPRIV
15 V
CSLP
10m
68
VL
RECO
CRECO
RNW4
390
10
SWAMP
CK
1000 m
RDC
CLIM
470 n
100 n
CVD
U4030B
430
CS
2.2 m
VL
U4030B
R
VD
PD
150k
20 mA
D
R
MUTE
20k
D
R
50k
93 7630 e
Figure 13. PD input
Figure 14. Mute input
Package Information
9.15
8.65
Package SO20
Dimensions in mm
12.95
12.70
7.5
7.3
2.35
0.25
0.25
0.10
0.4
10.50
10.20
1.27
11.43
20
11
technical drawings
according to DIN
specifications
13038
1
Rev. A2, 27-Jan-98
10
13 (14)
U4030B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC Semiconductor 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 Semiconductor GmbH 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 Semiconductor GmbH 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 Semiconductor GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423
14 (14)
Rev. A2, 27-Jan-98