Moteur de recherche de fiches techniques de composants électroniques
  French  ▼
ALLDATASHEET.FR

X  

LM1876 Fiches technique(PDF) 13 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor. Click here to check the latest version.
No de pièce LM1876
Description  Overture??Audio Power Amplifier Series Dual 20W Audio Power Amplifier with Mute and Standby Modes
Download  16 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  NSC [National Semiconductor (TI)]
Site Internet  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM1876 Fiches technique(HTML) 13 Page - National Semiconductor (TI)

Back Button LM1876 Datasheet HTML 8Page - National Semiconductor (TI) LM1876 Datasheet HTML 9Page - National Semiconductor (TI) LM1876 Datasheet HTML 10Page - National Semiconductor (TI) LM1876 Datasheet HTML 11Page - National Semiconductor (TI) LM1876 Datasheet HTML 12Page - National Semiconductor (TI) LM1876 Datasheet HTML 13Page - National Semiconductor (TI) LM1876 Datasheet HTML 14Page - National Semiconductor (TI) LM1876 Datasheet HTML 15Page - National Semiconductor (TI) LM1876 Datasheet HTML 16Page - National Semiconductor (TI)  
Zoom Inzoom in Zoom Outzoom out
 13 / 16 page
background image
Application Information (Continued)
under is higher than 25˚C, then the thermal resistance for the
heat sink, given all other things are equal, will need to be
smaller.
SUPPLY BYPASSING
The LM1876 has excellent power supply rejection and does
not require a regulated supply. However, to improve system
performance as well as eliminate possible oscillations, the
LM1876 should have its supply leads bypassed with
low-inductance capacitors having short leads that are lo-
cated close to the package terminals. Inadequate power
supply bypassing will manifest itself by a low frequency oscil-
lation known as “motorboating” or by high frequency insta-
bilities. These instabilities can be eliminated through multiple
bypassing utilizing a large tantalum or electrolytic capacitor
(10 µF or larger) which is used to absorb low frequency
variations and a small ceramic capacitor (0.1 µF) to prevent
any high frequency feedback through the power supply lines.
If adequate bypassing is not provided, the current in the sup-
ply leads which is a rectified component of the load current
may be fed back into internal circuitry. This signal causes
distortion at high frequencies requiring that the supplies be
bypassed at the package terminals with an electrolytic ca-
pacitor of 470 µF or more.
BRIDGED AMPLIFIER APPLICATION
The LM1876 has two operational amplifiers internally, allow-
ing for a few different amplifier configurations. One of these
configurations is referred to as “bridged mode” and involves
driving the load differentially through the LM1876’s outputs.
This configuration is shown in
Figure 2. Bridged mode op-
eration is different from the classical single-ended amplifier
configuration where one side of its load is connected to
ground.
A bridge amplifier design has a distinct advantage over the
single-ended configuration, as it provides differential drive to
the load, thus doubling output swing for a specified supply
voltage. Consequently, theoretically four times the output
power is possible as compared to a single-ended amplifier
under the same conditions. This increase in attainable output
power assumes that the amplifier is not current limited or
clipped.
A direct consequence of the increased power delivered to
the load by a bridge amplifier is an increase in internal power
dissipation. For each operational amplifier in a bridge con-
figuration, the internal power dissipation will increase by a
factor of two over the single ended dissipation. Thus, for an
audio power amplifier such as the LM1876, which has two
operational amplifiers in one package, the package dissipa-
tion will increase by a factor of four. To calculate the
LM1876’s maximum power dissipation point for a bridged
load, multiply equation (1) by a factor of four.
This value of P
DMAX can be used to calculate the correct size
heat sink for a bridged amplifier application. Since the inter-
nal dissipation for a given power supply and load is in-
creased by using bridged-mode, the heatsink’s
θ
SA will have
to decrease accordingly as shown by equation (3). Refer to
the section, Determining the Correct Heat Sink, for a more
detailed discussion of proper heat sinking for a given appli-
cation.
SINGLE-SUPPLY AMPLIFIER APPLICATION
The typical application of the LM1876 is a split supply ampli-
fier. But as shown in
Figure 3, the LM1876 can also be used
in a single power supply configuration. This involves using
some external components to create a half-supply bias
which is used as the reference for the inputs and outputs.
Thus, the signal will swing around half-supply much like it
swings around ground in a split-supply application. Along
with proper circuit biasing, a few other considerations must
be accounted for to take advantage of all of the LM1876
functions.
The LM1876 possesses a mute and standby function with in-
ternal logic gates that are half-supply referenced. Thus, to
enable either the Mute or Standby function, the voltage at
these pins must be a minimum of 2.5V above half-supply. In
single-supply systems, devices such as microprocessors
and simple logic circuits used to control the mute and
standby functions, are usually referenced to ground, not
half-supply. Thus, to use these devices to control the logic
circuitry of the LM1876, a “level shifter,” like the one shown in
Figure 5, must be employed. A level shifter is not needed in
a split-supply configuration since ground is also half-supply.
When the voltage at the Logic Input node is 0V, the 2N3904
is “off” and thus resistor R
c pulls up mute or standby input to
the supply. This enables the mute or standby function. When
the Logic Input is 5V, the 2N3904 is “on” and consequently,
the voltage at the collector is essentially 0V. This will disable
the mute or standby function, and thus the amplifier will be in
its normal mode of operation. R
shift, along with Cshift, creates
an RC time constant that reduces transients when the mute
or standby functions are enabled or disabled. Additionally,
R
shift limits the current supplied by the internal logic gates of
the LM1876 which insures device reliability. Refer to the
Mute Mode and Standby Mode sections in the Application
Information section for a more detailed description of these
functions.
CLICKS AND POPS
In the typical application of the LM1876 as a split-supply au-
dio power amplifier, the IC exhibits excellent “click” and “pop”
performance when utilizing the mute and standby modes. In
addition, the device employs Under-Voltage Protection,
which eliminates unwanted power-up and power-down tran-
sients. The basis for these functions are a stable and con-
stant half-supply potential. In a split-supply application,
ground is the stable half-supply potential. But in a
single-supply application, the half-supply needs to charge up
just like the supply rail, V
CC. This makes the task of attaining
a clickless and popless turn-on more challenging. Any un-
even charging of the amplifier inputs will result in output
clicks and pops due to the differential input topology of the
LM1876.
DS012072-12
FIGURE 5. Level Shift Circuit
www.national.com
13


Numéro de pièce similaire - LM1876

FabricantNo de pièceFiches techniqueDescription
logo
National Semiconductor ...
LM1876 NSC-LM1876 Datasheet
696Kb / 20P
   Dual 20W Audio Power Amplifier with Mute and Standby Modes
logo
Texas Instruments
LM1876 TI1-LM1876 Datasheet
1Mb / 27P
[Old version datasheet]   Audio Power Amplifier Series
LM1876T TI1-LM1876T Datasheet
1Mb / 27P
[Old version datasheet]   Audio Power Amplifier Series
LM1876T/NOPB TI1-LM1876T/NOPB Datasheet
1Mb / 27P
[Old version datasheet]   Audio Power Amplifier Series
LM1876TF TI1-LM1876TF Datasheet
1Mb / 27P
[Old version datasheet]   Audio Power Amplifier Series
More results

Description similaire - LM1876

FabricantNo de pièceFiches techniqueDescription
logo
National Semiconductor ...
LM1876 NSC-LM1876_03 Datasheet
696Kb / 20P
   Dual 20W Audio Power Amplifier with Mute and Standby Modes
LM4700 NSC-LM4700 Datasheet
529Kb / 15P
   Overture??Audio Power Amplifier Series 30W Audio Power Amplifier with Mute and Standby Modes
LM4701 NSC-LM4701 Datasheet
541Kb / 15P
   LM4701 Overture??Audio Power Amplifier Series 30W Audio Power Amplifier with Mute and Standby Modes
logo
Texas Instruments
LM4765 TI1-LM4765 Datasheet
817Kb / 24P
[Old version datasheet]   LM4765 Overture??Audio Power Amplifier Series Dual 30W Audio Power Amplifier with Mute and Standby Modes
logo
National Semiconductor ...
LM4765 NSC-LM4765 Datasheet
536Kb / 15P
   Audio Power Amplifier Series Dual 30W Audio Power Amplifier with Mute and Standby Modes
LM4782 NSC-LM4782_06 Datasheet
1Mb / 27P
   Overture Audio Power Amplifier Series 3 Channel 25W Audio Power Amplifier with Mute and Standby
LM4731 NSC-LM4731 Datasheet
640Kb / 16P
   Stereo 25W Audio Power Amplifier with Mute and Standby Modes
logo
Texas Instruments
LM4766 TI-LM4766_15 Datasheet
955Kb / 23P
[Old version datasheet]    Overture Audio Power Amplifier Series Dual 40W Audio Power Amplifier with Mute
logo
National Semiconductor ...
LM4730 NSC-LM4730 Datasheet
643Kb / 17P
   Stereo 14W Audio Power Amplifier with Mute and Standby Modes
logo
Texas Instruments
LM4734 TI1-LM4734_14 Datasheet
1Mb / 28P
[Old version datasheet]   3 Channel 20W Audio Power Amplifier with Mute and Standby
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16


Fiches technique Télécharger

Go To PDF Page


Lien URL




Politique de confidentialité
ALLDATASHEET.FR
ALLDATASHEET vous a-t-il été utile ?  [ DONATE ] 

À propos de Alldatasheet   |   Publicité   |   Contactez-nous   |   Politique de confidentialité   |   Echange de liens   |   Fabricants
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com