LM1036N National Semiconductor, LM1036N Datasheet - Page 6

• Manufacturer Part Number: LM1036N
• Description: Audio Power Amplifier IC
• Manufacturer: National Semiconductor

Specifications of LM1036N

• No. Of Channels: 2
• Amplifier Case Style: DIP
• No. Of Pins: 20
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Mounting Type: Through Hole
• Package / Case: 20-DIP
• No. Of Amplifiers: 2
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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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
increased, and for increased bass range C
duced.
Figure 1 shows the typical tone response obtained in the
standard application circuit. (C
sponse curves are given for various amounts of boost and
cut.
Figure 2 and Figure 3 show the effect of changing the
response defining capacitors C
C
values of the bypass capacitors may become significant and
affect the lower frequencies in the bass response curves.
b
FIGURE 1. Tone Characteristic (Gain vs Frequency)
FIGURE 2. Tone Characteristic (Gain vs Frequency)
/4 respectively, giving increased tone control ranges. The
t
t
=0.01 µF, C
and C
b
to 2Ct, C
00514205
00514204
b
=0.39 µF). Re-
b
must be re-
b
/2 and 4C
t
must be
t
,
6
Figure 4 shows the effect of changing C
opposite direction to C
control ranges. The various results corresponding to the
different C
give a particular emphasis to, for example, the bass control.
The particular case with C
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
dB less than the standard circuit when R=X
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 approxi-
mately 3 dB less with X
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
and C
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.
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 Hz–16 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
ranges.
Figure 7 shows the typical loudness curves obtained in the
standard application circuit at various volume levels
(C
FIGURE 3. Tone Characteristic (Gain vs Frequency)
b
=0.39 µF).
b
for greater control range also has the effect of
t
t
and C
or C
b
b
or by changing the nominal control voltage
values may be mixed if it is required to
t
/2, 2C
t
C
. The treble boost and cut will be 3
at this value. An example of such
b
/2, C
b
respectively giving reduced
t
is illustrated in Figure 5.
00514206
t
C
and C
.
b
in the
t