NSC LM1036N

LM1036
Dual DC Operated Tone/Volume/Balance Circuit
General Description
Features
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 loudness compensation to be simply effected.
Four control inputs provide control of the bass, treble, balance and volume functions through application of DC voltages 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.
n
n
n
n
n
Wide supply voltage range, 9V to 16V
Large volume control range, 75 dB typical
Tone control, ± 15 dB typical
Channel separation, 75 dB typical
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
© 1999 National Semiconductor Corporation
DS005142
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LM1036 Dual DC Operated Tone/Volume/Balance Circuit
January 1995
Absolute Maximum Ratings (Note 1)
Storage Temperature Range
Power Dissipation
Lead Temp. (Soldering, 10 seconds)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
Control Pin Voltage (Pins 4, 7, 9, 12, 14)
Operating Temperature Range
−65˚C to +150˚C
1W
260˚C
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.
16V
VCC
0˚C to +70˚C
Electrical Characteristics
VCC = 12V, TA = 25˚C (unless otherwise stated)
Parameter
Supply Voltage Range
Conditions
Min
Pin 11
Supply Current
Zener Regulated Output
Typ
9
35
Units
16
V
45
mA
5
mA
Pin 17
Voltage
5.4
Current
Maximum Output Voltage
Max
Pins 8, 13; f = 1 kHz
VCC = 9V, Maximum Gain
V
0.8
Vrms
VCC = 12V
0.8
1.0
Vrms
Maximum Input Voltage
Pins 2, 19; f = 1 kHz, VCC 2V
Gain = −10 dB
1.3
1.6
Vrms
Input Resistance
20
30
kΩ
Volume Control Range
Pins 2, 19; f = 1 kHz
Pins 8, 13; f = 1 kHz
V(Pin 12) = V(Pin 17); f = 1 kHz
f = 1 kHz
Gain Tracking
f = 1 kHz
Channel 1–Channel 2
0 dB through −40 dB
1
2
dB
Balance Control Range
−40 dB through −60 dB
Pins 8, 13; f = 1 kHz
1
dB
Output Resistance
Maximum Gain
−2
0
70
75
−26
Bass Control Range
(Note 3)
Treble Control Range
(Note 3)
Total Harmonic Distortion
Channel Separation
Signal/Noise Ratio
f = 40 Hz, Cb = 0.39 µF
V(Pin 14) = V(Pin 17)
2
dB
dB
3
dB
−20
dB
12
15
18
dB
V(Pin 14) = 0V
f = 16 kHz, Ct, = 0.01 µF
V(Pin 4) = V(Pin 17)
−12
−15
−18
dB
12
15
18
dB
V(Pin 4) = 0V
f = 1 kHz, VIN = 0.3 Vrms
Gain = 0 dB
−12
−15
−18
dB
0.06
0.3
%
Gain = −30 dB
f = 1 kHz, Maximum Gain
60
Unweighted 100 Hz–20 kHz
Maximum Gain, 0 dB = 0.3 Vrms
CCIR/ARM (Note 4)
Gain = 0 dB, VIN = 0.3 Vrms
Gain = −20 dB, VIN = 1.0 Vrms
Output Noise Voltage at
Ω
20
75
CCIR/ARM (Note 4)
0.03
%
75
dB
80
dB
79
dB
72
dB
10
16
µV
Minimum Gain
Supply Ripple Rejection
Control Input Currents
200 mVrms, 1 kHz Ripple
Pins 4, 7, 9, 12, 14 (V = 0V)
Frequency Response
−1 dB (Flat Response
35
250
20 Hz–16 kHz)
Note 2: The maximum permissible input level is dependent on tone and volume settings. See Application Notes.
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50
−0.6
2
dB
−2.5
µA
kHz
Electrical Characteristics
(Continued)
Note 3: The tone control range is defined by capacitors Cb and Ct. 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
Balance Control
Characteristic
Tone Control Characteristic
DS005142-22
DS005142-21
DS005142-20
Tone Characteristic (Gain
vs Frequency)
Tone Characteristic (Gain
vs Frequency)
DS005142-23
Input Signal Handling vs
Supply Voltage
Loudness Compensated
Volume Characteristic
DS005142-25
DS005142-24
Channel Separation vs
Frequency
THD vs Gain
DS005142-27
DS005142-28
DS005142-26
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Typical Performance Characteristics
Loudness Control
Characteristic
(Continued)
Output Noise Voltage
vs Gain
THD vs Input Voltage
DS005142-31
DS005142-29
DS005142-30
Application Notes
maximum boost defined by Cb and Ct. 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 response, Cb and Ct as given in Application Circuit.) Modification to the loudness characteristic is possible by changing
the capacitors Cb and Ct for a different basic response or, by
a resistor network between pins 7 and 12 for a different
threshold and slope.
TONE RESPONSE
The maximum boost and cut can be optimized for individual
applications by selection of the appropriate values of Ct
(treble) and Cb (bass).
The tone responses are defined by the relationships:
SIGNAL HANDLING
The volume control function of the LM1036 is carried out in
two stages, controlled by the DC voltage on pin 12, to improve 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, VCC = 12V (0.8 Vrms, VCC = 9V). At reduced gain
( < −6 dB)the input stage will overload if the input level exceeds 1.6 Vrms, VCC = 12V (1.1 Vrms, VCC = 9V). As there is
volume control on the input stages, the inputs may be operated with a lower overload margin than would otherwise be
acceptable, allowing a possible improvement in signal to
noise ratio.
Where ab = at = 0 for maximum bass and treble boost respectively and ab = at = 1 for maximum cut.
For the values of Cb and Ct of 0.39 µF and 0.01 µF 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 condition. 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 applying a DC control voltage to pin 7. This operates on the tone
control stages to produce an additional boost limited by the
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Application Circuit
DS005142-3
Applications Information
Figure 2 and Figure 3 show the effect of changing the response defining capacitors Ct and Cb to 2Ct, Cb/2 and 4Ct,
Cb/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.
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, basically for an increase in the treble control range Ct must be increased, and for increased bass range Cb must be reduced.
Figure 1 shows the typical tone response obtained in the
standard application circuit. (Ct = 0.01 µF, Cb = 0.39 µF). Response curves are given for various amounts of boost and
cut.
DS005142-5
FIGURE 2. Tone Characteristic (Gain vs Frequency)
DS005142-6
DS005142-4
FIGURE 3. Tone Characteristic (Gain vs Frequency)
FIGURE 1. Tone Characteristic (Gain vs Frequency)
5
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Applications Information
(Continued)
Figure 4 shows the effect of changing Ct and Cb in the opposite direction to Ct/2, 2Cb respectively giving reduced control
ranges. The various results corresponding to the different Ct
and Cb values may be mixed if it is required to give a particular emphasis to, for example, the bass control. The particular
case with Cb/2, Ct 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 Ct. The treble boost and cut will be 3
dB less than the standard circuit when R = XC.
A similar effect may be obtained for the bass response by reducing 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 kΩ and the bass boost/cut will be approximately 3 dB less with XC 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 response.
It will be seen from Figure 2 and Figure 3 that modifying Ct
and Cb for greater control range also has the effect of flattening 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.
DS005142-7
FIGURE 4. Tone Characteristic (Gain vs Frequency)
DS005142-8
FIGURE 5. Tone Characteristic (Gain vs Frequency)
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 output amplifiers may be detected below a certain level, and
used to bias back the bass control from a high boost condition, 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 normally 1 dB more bass than treble boost (40 Hz–16 kHz) with
loudness control in the standard circuit. If a greater difference is desired, it is necessary to introduce an offset by
means of Ct or Cb or by changing the nominal control voltage
ranges.
DS005142-9
FIGURE 6. Tone Characteristic (Gain vs Frequency)
Figure 7 shows the typical loudness curves obtained in the
standard application circuit at various volume levels
(Cb = 0.39 µF).
DS005142-10
FIGURE 7. Loudness Compensated Volume
Characteristic
Figure 8 and Figure 9 illustrate the loudness characteristics
obtained with Cb changed to Cb/2 and Cb/4 respectively, Ct
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Applications Information
(Continued)
being kept at the nominal 0.01 µF. 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 offsetting the voltage applied to pin 7 towards the control reference 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 reduce 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 illustrated in Figure 12, With a suitable level shifting network between pins 12 and 7, the onset of loudness control and its
rate of change may be readily modified.
DS005142-12
FIGURE 9. Loudness Compensated Volume
Characteristic
DS005142-13
FIGURE 10. Loudness Compensated Volume
Characteristic
DS005142-11
FIGURE 8. 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
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 Cb and
Ct, it is possible to arrange for operation over a wide frequency range for possible use in wide band equalization applications. As an example Figure 15 shows the responses
obtained centered on 10 kHz with Cb = 0.039 µF and
Ct = 0.001 µF.
(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 control range and modifying Ct, Cb, to compensate. A circuit illustrating 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.
DS005142-16
FIGURE 13. Modified Application Circuit for Additional Bass Boost with Loudness Control
DS005142-18
DS005142-17
FIGURE 15. Tone Characteristic (Gain vs Frequency)
FIGURE 14. Loudness Compensated Volume
Characteristic
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Simplified Schematic Diagram
(One Channel)
DS005142-19
*Connections reversed
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LM1036 Dual DC Operated Tone/Volume/Balance Circuit
Physical Dimensions
inches (millimeters) unless otherwise noted
Molded Dual-In-Line Package (N)
Order Number LM1036N
NS Package Number N20A
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