LM1036
Dual DC Operated Tone/Volume/Balance Circuit
General Description
The LM1036 is a DC controlled tone (bass/treble), volume
and balance circuit for stereo applications in car radio, TV
and audio systems. An additional control input allows loud-
ness compensation to be simply effected.
Four control inputs provide control of the bass, treble, bal-
ance and volume functions through application of DC volt-
ages from a remote control system or, alternatively, from four
potentiometers which may be biased from a zener regulated
supply provided on the circuit.
Each tone response is defined by a single capacitor chosen
to give the desired characteristic.
Features
n
Wide supply voltage range, 9V to 16V
n
Large volume control range, 75 dB typical
n
Tone control,
15 dB typical
n
Channel separation, 75 dB typical
n
Low distortion, 0.06% typical for an input level of 0.3
Vrms
n
High signal to noise, 80 dB typical for an input level of
0.3 Vrms
n
Few external components required
Block and Connection Diagram
Dual-In-Line Package
DS005142-1
Order Number LM1036N
See NS Package Number N20A
January 1995
LM1036
Dual
DC
Operated
T
one/V
olume/Balance
Circuit
1999 National Semiconductor Corporation
DS005142
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
16V
Control Pin Voltage (Pins 4, 7, 9, 12, 14)
V
CC
Operating Temperature Range
0C to +70C
Storage Temperature Range
-65C to +150C
Power Dissipation
1W
Lead Temp. (Soldering, 10 seconds)
260C
Note 1: "Absolute Maximum Ratings" indicate limits beyond which damage
to the device may occur. Operating Ratings indicate conditions for which the
device is functional, but do not guarantee specific performance limits.
Electrical Characteristics
V
CC
=12V, T
A
=25C (unless otherwise stated)
Parameter
Conditions
Min
Typ
Max
Units
Supply Voltage Range
Pin 11
9
16
V
Supply Current
35
45
mA
Zener Regulated Output
Pin 17
Voltage
5.4
V
Current
5
mA
Maximum Output Voltage
Pins 8, 13; f=1 kHz
V
CC
=9V, Maximum Gain
0.8
Vrms
V
CC
=12V
0.8
1.0
Vrms
Maximum Input Voltage
Pins 2, 19; f=1 kHz, V
CC
2V
1.3
1.6
Vrms
Gain=-10 dB
Input Resistance
Pins 2, 19; f=1 kHz
20
30
k
Output Resistance
Pins 8, 13; f=1 kHz
20
Maximum Gain
V(Pin 12)=V(Pin 17); f=1 kHz
-2
0
2
dB
Volume Control Range
f=1 kHz
70
75
dB
Gain Tracking
f=1 kHz
Channel 1Channel 2
0 dB through -40 dB
1
3
dB
-40 dB through -60 dB
2
dB
Balance Control Range
Pins 8, 13; f=1 kHz
1
dB
-26
-20
dB
Bass Control Range
f=40 Hz, C
b
=0.39 F
(Note 3)
V(Pin 14)=V(Pin 17)
12
15
18
dB
V(Pin 14)=0V
-12
-15
-18
dB
Treble Control Range
f= 16 kHz, C
t
,=0.01 F
(Note 3)
V(Pin 4)=V(Pin 17)
12
15
18
dB
V(Pin 4)=0V
-12
-15
-18
dB
Total Harmonic Distortion
f=1 kHz, V
IN
=0.3 Vrms
Gain=0 dB
0.06
0.3
%
Gain=-30 dB
0.03
%
Channel Separation
f=1 kHz, Maximum Gain
60
75
dB
Signal/Noise Ratio
Unweighted 100 Hz20 kHz
80
dB
Maximum Gain, 0 dB=0.3 Vrms
CCIR/ARM (Note 4)
Gain=0 dB, V
IN
=0.3 Vrms
75
79
dB
Gain=-20 dB, V
IN
=1.0 Vrms
72
dB
Output Noise Voltage at
CCIR/ARM (Note 4)
10
16
V
Minimum Gain
Supply Ripple Rejection
200 mVrms, 1 kHz Ripple
35
50
dB
Control Input Currents
Pins 4, 7, 9, 12, 14 (V=0V)
-0.6
-2.5
A
Frequency Response
-1 dB (Flat Response
250
kHz
20 Hz16 kHz)
Note 2: The maximum permissible input level is dependent on tone and volume settings. See Application Notes.
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2
Electrical Characteristics
(Continued)
Note 3: The tone control range is defined by capacitors C
b
and C
t
. See Application Notes.
Note 4: Gaussian noise, measured over a period of 50 ms per channel, with a CCIR filter referenced to 2 kHz and an average-responding meter.
Typical Performance Characteristics
Volume Control
Characteristics
DS005142-20
Balance Control
Characteristic
DS005142-21
Tone Control Characteristic
DS005142-22
Tone Characteristic (Gain
vs Frequency)
DS005142-23
Tone Characteristic (Gain
vs Frequency)
DS005142-24
Loudness Compensated
Volume Characteristic
DS005142-25
Input Signal Handling vs
Supply Voltage
DS005142-26
THD vs Gain
DS005142-27
Channel Separation vs
Frequency
DS005142-28
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Typical Performance Characteristics
(Continued)
Application Notes
TONE RESPONSE
The maximum boost and cut can be optimized for individual
applications by selection of the appropriate values of C
t
(treble) and C
b
(bass).
The tone responses are defined by the relationships:
Where a
b
=a
t
=0 for maximum bass and treble boost respec-
tively and a
b
=a
t
=1 for maximum cut.
For the values of C
b
and C
t
of 0.39 F and 0.01 F as shown
in the Application Circuit, 15 dB of boost or cut is obtained at
40 Hz and 16 kHz.
ZENER VOLTAGE
A zener voltage (pin 17=5.4V) is provided which may be
used to bias the control potentiometers. Setting a DC level of
one half of the zener voltage on the control inputs, pins 4, 9,
and 14, results in the balanced gain and flat response condi-
tion. Typical spread on the zener voltage is
100 mV and
this must be taken into account if control signals are used
which are not referenced to the zener voltage. If this is the
case, then they will need to be derived with similar accuracy.
LOUDNESS COMPENSATION
A simple loudness compensation may be effected by apply-
ing a DC control voltage to pin 7. This operates on the tone
control stages to produce an additional boost limited by the
maximum boost defined by C
b
and C
t
. There is no loudness
compensation when pin 7 is connected to pin 17. Pin 7 can
be connected to pin 12 to give the loudness compensated
volume characteristic as illustrated without the addition of
further external components. (Tone settings are for flat re-
sponse, C
b
and C
t
as given in Application Circuit.) Modifica-
tion to the loudness characteristic is possible by changing
the capacitors C
b
and C
t
for a different basic response or, by
a resistor network between pins 7 and 12 for a different
threshold and slope.
SIGNAL HANDLING
The volume control function of the LM1036 is carried out in
two stages, controlled by the DC voltage on pin 12, to im-
prove signal handling capability and provide a reduction of
output noise level at reduced gain. The first stage is before
the tone control processing and provides an initial 15 dB of
gain reduction, so ensuring that the tone sections are not
overdriven by large input levels when operating with a low
volume setting. Any combination of tone and volume settings
may be used provided the output level does not exceed
1 Vrms, V
CC
=12V (0.8 Vrms, V
CC
=9V). At reduced gain
(
<
-6 dB)the input stage will overload if the input level ex-
ceeds 1.6 Vrms, V
CC
=12V (1.1 Vrms, V
CC
=9V). As there is
volume control on the input stages, the inputs may be oper-
ated with a lower overload margin than would otherwise be
acceptable, allowing a possible improvement in signal to
noise ratio.
Loudness Control
Characteristic
DS005142-29
Output Noise Voltage
vs Gain
DS005142-30
THD vs Input Voltage
DS005142-31
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Application Circuit
Applications Information
OBTAINING MODIFIED RESPONSE CURVES
The LM1036 is a dual DC controlled bass, treble, balance
and volume integrated circuit ideal for stereo audio systems.
In the various applications where the LM1036 can be used,
there may be requirements for responses different to those
of the standard application circuit given in the data sheet.
This application section details some of the simple variations
possible on the standard responses, to assist the choice of
optimum characteristics for particular applications.
TONE CONTROLS
Summarizing the relationship given in the data sheet, basi-
cally for an increase in the treble control range C
t
must be in-
creased, and for increased bass range C
b
must be reduced.
Figure 1 shows the typical tone response obtained in the
standard application circuit. (C
t
=0.01 F, C
b
=0.39 F). Re-
sponse curves are given for various amounts of boost and
cut.
Figure 2 and Figure 3 show the effect of changing the re-
sponse defining capacitors C
t
and C
b
to 2Ct, C
b
/2 and 4C
t
,
C
b
/4 respectively, giving increased tone control ranges. The
values of the bypass capacitors may become significant and
affect the lower frequencies in the bass response curves.
DS005142-3
DS005142-4
FIGURE 1. Tone Characteristic (Gain vs Frequency)
DS005142-5
FIGURE 2. Tone Characteristic (Gain vs Frequency)
DS005142-6
FIGURE 3. Tone Characteristic (Gain vs Frequency)
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Applications Information
(Continued)
Figure 4 shows the effect of changing C
t
and C
b
in the oppo-
site direction to C
t
/2, 2C
b
respectively giving reduced control
ranges. The various results corresponding to the different C
t
and C
b
values may be mixed if it is required to give a particu-
lar emphasis to, for example, the bass control. The particular
case with C
b
/2, C
t
is illustrated in
Figure 5.
Restriction of Tone Control Action at High or Low
Frequencies
It may be desired in some applications to level off the tone
responses above or below certain frequencies for example
to reduce high frequence noise.
This may be achieved for the treble response by including a
resistor in series with C
t
. The treble boost and cut will be 3
dB less than the standard circuit when R=X
C
.
A similar effect may be obtained for the bass response by re-
ducing the value of the AC bypass capacitors on pins 5
(channel 1) and 16 (channel 2). The internal resistance at
these pins is 1.3 k
and the bass boost/cut will be approxi-
mately 3 dB less with X
C
at this value. An example of such
modified response curves is shown in
Figure 6. The input
coupling capacitors may also modify the low frequency re-
sponse.
It will be seen from
Figure 2 and Figure 3 that modifying C
t
and C
b
for greater control range also has the effect of flatten-
ing the tone control extremes and this may be utilized, with
or without additional modification as outlined above, for the
most suitable tone control range and response shape.
Other Advantages of DC Controls
The DC controls make the addition of other features easy to
arrange. For example, the negative-going peaks of the out-
put amplifiers may be detected below a certain level, and
used to bias back the bass control from a high boost condi-
tion, to prevent overloading the speaker with low frequency
components.
LOUDNESS CONTROL
The loudness control is achieved through control of the tone
sections by the voltage applied to pin 7; therefore, the tone
and loudness functions are not independent. There is nor-
mally 1 dB more bass than treble boost (40 Hz16 kHz) with
loudness control in the standard circuit. If a greater differ-
ence is desired, it is necessary to introduce an offset by
means of C
t
or C
b
or by changing the nominal control voltage
ranges.
Figure 7 shows the typical loudness curves obtained in the
standard application circuit at various volume levels
(C
b
=0.39 F).
Figure 8 and Figure 9 illustrate the loudness characteristics
obtained with C
b
changed to C
b
/2 and C
b
/4 respectively, C
t
DS005142-7
FIGURE 4. Tone Characteristic (Gain vs Frequency)
DS005142-8
FIGURE 5. Tone Characteristic (Gain vs Frequency)
DS005142-9
FIGURE 6. Tone Characteristic (Gain vs Frequency)
DS005142-10
FIGURE 7. Loudness Compensated Volume
Characteristic
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Applications Information
(Continued)
being kept at the nominal 0.01 F. These values naturally
modify the bass tone response as in
Figure 2 and Figure 3.
With pins 7 (loudness) and 12 (volume) directly connected,
loudness control starts at typically -8 dB volume, with most
of the control action complete by -30 dB.
Figure 10 and Figure 11 show the effect of resistively offset-
ting the voltage applied to pin 7 towards the control refer-
ence voltage (pin 17). Because the control inputs are high
impedance, this is easily done and high value resistors may
be used for minimal additional loading. It is possible to re-
duce the rate of onset of control to extend the active range to
-50 dB volume control and below.
The control on pin 7 may also be divided down towards
ground bringing the control action on earlier. This is illus-
trated in
Figure 12, With a suitable level shifting network be-
tween pins 12 and 7, the onset of loudness control and its
rate of change may be readily modified.
DS005142-11
FIGURE 8. Loudness Compensated Volume
Characteristic
DS005142-12
FIGURE 9. Loudness Compensated Volume
Characteristic
DS005142-13
FIGURE 10. Loudness Compensated Volume
Characteristic
DS005142-14
FIGURE 11. Loudness Compensated Volume
Characteristic
DS005142-15
FIGURE 12. Loudness Compensated Volume Characteristic
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Applications Information
(Continued)
When adjusted for maximum boost in the usual application
circuit, the LM1036 cannot give additional boost from the
loudness control with reducing gain. If it is required, some
additional boost can be obtained by restricting the tone con-
trol range and modifying C
t
, C
b
, to compensate. A circuit il-
lustrating this for the case of bass boost is shown in Figure
13. The resulting responses are given in
Figure 14 showing
the continuing loudness control action possible with bass
boost previously applied.
USE OF THE LM1036 ABOVE AUDIO FREQUENCIES
The LM1036 has a basic response typically 1 dB down at
250 kHz (tone controls flat) and therefore by scaling C
b
and
C
t
, it is possible to arrange for operation over a wide fre-
quency range for possible use in wide band equalization ap-
plications. As an example
Figure 15 shows the responses
obtained centered on 10 kHz with C
b
=0.039 F and
C
t
=0.001 F.
DS005142-16
FIGURE 13. Modified Application Circuit for Additional Bass Boost with Loudness Control
DS005142-17
FIGURE 14. Loudness Compensated Volume
Characteristic
DS005142-18
FIGURE 15. Tone Characteristic (Gain vs Frequency)
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Simplified Schematic Diagram
(One Channel)
DS005142-19
*Connections reversed
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Physical Dimensions
inches (millimeters) unless otherwise noted
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Molded Dual-In-Line Package (N)
Order Number LM1036N
NS Package Number N20A
LM1036
Dual
DC
Operated
T
one/V
olume/Balance
Circuit
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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