18W Car Stereo Amplifier Rise

This automobile stereo amplifier project is a class AB audio power amplifier using the Hitachi HA13118 module. It not only can be used in automobile application but also in any transportable or home amplifier process. It is simple to construct & has a maximum of outside parts. The module has a high power output from a low voltage supply using the bridge tied load system, & a high gain of 55dB.

This project will be useful in applications where the input signal is a low level, without requiring the use of a separate pre-amplifier. This IC module has a built in surge protection circuit, thermal shutdown circuit, ground fault protection circuit & power supply fault protection circuit making it reliable.

The Specifications of this project 
D.C. Input : 8 – 18V at 1-2 A

Power output : 18W maximum, 4 ohm load, 18V DC supply

S/N ratio : > 70 dB

THD : < 0.2% @ 1W

Freq. Response : ~ 30 Hz to 30 kHz, –3 dB

Input level : < 25 mV, for full output (G > 50dB)

Input Impedance : ~ 30 k ohm

The supply voltage necessary for this project is 8 -18V DC, at least one to two Amps. Maximum output power will only be obtained with a power supply of 18V at greater than two A, using a four ohm speaker. The power supply ought to be well filtered to reduce mains hum, a regulated supply will reduce noise even further. Additional filtering is unnecessary if operating from a battery supply.

Circuit Diagram Description

Most of the circuitry is contained within the amplifier module. C10 is the input coupling capacitor and blocks DC from the input. C11 bypasses any RF which may be present at the input. C1 & C2 provide an AC ground for the inverting inputs of the IC. R1/C7 and R2/C8 provide a high frequency load for stability with difficult speakers. C five & C six provide bootstrap feedback for the IC. C9 & C12 provide power supply filtering.

An externally mounted logarithmic potentiometer of between 10k ohm and 50k ohm, is used depending on the desired input impedance. The impedance ought to be keep as high as feasible for a guitar amp, unless using a separate pre-amp. Make sure-that the heat sink is mounted to the module.

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Hybrid Headphone Amplifier

Potentially, headphone listening can be technically superior since room reflections are eliminated and the intimate contact between transducer and ear mean that only tiny amounts of power are required. The small power requirement means that transducers can be operated at a small fraction of their full excursion capabilities thus reducing THD and other non-linear distortions. This design of a dedicated headphones amplifier is potentially controversial in that it has unity voltage gain and employs valves and transistors in the same design. Normal headphones have an impedance of 32R per channel. The usual standard line output of 775 mV to which all quality equipment aspires will generate a power of U2 / R = 0.7752 / 32 = 18 mW per channel across a headphone of this impedance.

An examination of available headphones at well known high street emporiums revealed that the sensitivity varied from 96 dB to 103db/mW! So, in practice the circuit will only require unity gain to reach deafening levels. As a unity gain design is required it is quite possible to employ a low distortion output stage. The obvious choice is an emitter follower. This has nearly unity gain combined with a large amount of local feedback. Unfortunately the output impedance of an emitter follower is dependent upon the source impedance. With a volume control, or even with different signal sources this will vary and could produce small but audible changes in sound quality.

To prevent this, the output stage is driven by a cathode follower,based around an ECC82 valve (US equivalent: 12AU7).
This device, as opposed to a transistor configuration, enables the output stage to be driven with a constant value, low impedance. In other words, the signal from the low impedance point is used to drive the high impedance of the output stage, a situation which promotes low overall THD. At the modest output powers required of the circuit, the only sensible choice is a Class A circuit. In this case the much vaunted single-ended output stage is employed and that comprises of T3 and constant current source T1-T2.

Hybrid Headphone Amplifier Circuit Diagram

The constant current is set by the Vbe voltage of T1 applied across R5 With its value of 22R, the current is set at 27 mA. T3 is used in the emitter follower mode with high input impedance and low output impedance. Indeed the main problem of using a valve at low voltages is that it’s fairly difficult to get any real current drain. In order to prevent distortion the output stage shouldn’t be allowed to load the valve. This is down to the choice of output device. A BC517 is used for T3 because of its high current gain, 30,000 at 2 mA! Since we have a low impedance output stage, the load may be capacitively coupled via C4. Some purists may baulk at the idea of using an electrolytic for this job but he fact remains that distortion generated by capacitive coupling is at least two orders of magnitude lower than transformer coupling.

The rest of the circuitry is used to condition the various voltages used by the circuit. In order to obtain a linear output the valve grid needs to be biased at half the supply voltage. This is the function of the voltage divider R4 and R2. Input signals are coupled into the circuit via C1 and R1. R1, connected between the voltage divider and V1’s grid defines the input impedance of the circuit. C1 has sufficiently large a value to ensure response down to 2 Hz. Although the circuit does a good job of rejecting line noise on its own due to the high impedance of V1’s anode and T3’s collector current, it needs a little help to obtain a silent background in the absence of signal.

The ‘help’ is in the form of the capacitance multiplier circuit built around T5. Another BC517 is used here to avoid loading of the filter comprising R7 and C5. In principle the capacitance of C5 is multiplied by the gain of T5. In practice the smooth dc applied to T5’s base appears at low impedance at its emitter. An important added advantage is that the supply voltage is applied slowly on powering up. This is of course due to the time taken to fully charge C5 via R7. No trace of hum or ripple can be seen here on the ‘scope. C2 is used to ensure stability at RF. The DC supply is also used to run the valve heater. The ECC82 has an advantage here in that its heater can be connected for operate from 12.6 V. To run it T4 is used as a series pass element. Base voltage is obtained from the emitter of T5. T4 has very low output impedance, about 160 mR and this helps to prevent extraneous signals being picked up from the heater wiring. Connecting the transistor base to C5 also lets the valve heater warm up gently. A couple of volts only are lost across T4 and although the device runs warm it doesn’t require a heat-sink.

Source:  http://www.ecircuitslab.com/2011/06/hybrid-headphone-amplifier.html

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Stereo Headphone Amplifier Using LM4882

Using the LM48824 integrated circuit , can be designed a very simple stereo headphone amplifier for portable devices .

Stereo Headphone Amplifier Circuit diagram

The LM48824’s Stereo Headphone Amplifier (Class G architecture ) increases audio (MP3, mobile TV, etc.) playback time with its adaptive power supply approach that enables very low supply rails, which doubles the power-efficiency compared to typical Class AB headphone amplifiers.

A high output impedance mode allows the LM48824s outputs to be driven by an external source without degrading the signal.

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Simple Operational Amplifier DC Motor Driver

Using a simple operational amplifier and some other common electronic components can be designed a very simple DC motor driver that can be used for a 200mA motor application . Rb sets the bias point for transistors Q1 and Q2.

Because Vbe(ON) varies greatly with temperature, a guardband is required to prevent Q1 and Q2 from conducting simultaneously. RB should be selected such that the transistors do not conduct until lM equals the op amp quiescent supply current, Isy . The transistors will begin to conduct at about Vbe (on) = 0.5V. In this project :
RB= [vbe(on)/(lSY+ Im)]= 0.5/(0.0025 + 0.0025)=100 ohms

To maximize voltage swing across the motor, V1 must be minimized. If at full load V1 = 0.2V with V+ = 15V and VBE1 = 0.8V, the voltage across the motor will be:
VM = (V+ - 2) - VBE1 - V1 = (15 - 2) - 0.8 - 0.2 = 12.0V Vin may be scaled with a resistive divider as:
VIN= (R1 + R2)/R2 With R1 = 240k and R2 = 10k, VIN =5 volt lM = 200mA.

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Clean High gain Differential Instrumentation Amplifier

This circuit includes input guarding, cable bootstrapping, and bias current compensation .
Differential bandwidth is reduced by Cl which also makes common-mode rejection less dependent on matching of input amplifiers

 High gain Differential Instrumentation Amplifier

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10 Watts Mosfet Audio Amplifier

The diagram shown here is a MOSFET amplifier circuit 10W of sound that only requires a single source. Single railway material rarely used in power amplifiers class-B. However, for low power applications like this is very thin. Actually I have this circuit a old cassette player is still working and republish as it is. The BD512 and BD522 power MOSFETs is obsolete now and you can use any other power MOSFET game instead of them.



Transistors Q1 and Q2 are connected as a Darlington pair works as a preamp. R3 preset controls the quiescent current, while R2 provides. Output is coupled to the speakers through capacitor C4. Capacitor C5 is the power supply filter and C2 is the input DC decoupling capacitor.

Notes.

• The circuit can be assembled on a vero board.
• Use 30V DC for powering the circuit.
• Do not expect much performance from this amplifier.
• Capacitors C3, C4, C5 must be rated 50V and C2 can be 10V.
• Use a 8 ohm 15W speaker as load.

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TBA820 low power audio amplifier

At this time amplifier circuit based on IC KA2201, TBA820M, LM820M, and U820. You can use all ic is the series under the scheme. This amplifier circuit has a very small output power or low at 2W. Required supply voltage from 3 volts to a maximum of 16 volts.

Below is a scheme of this power amplifier

Part List

R1 = 100K

R2 = 120R

R3 = 100R

C1 = 100nF

C2 = 100uF
C3 = 470uF
C4 = 220pF

C5 = 47uF

C6 = 100uF

IC = KA2201 , LM820M , TBA820M , U820M

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100 Watt Power Amplifier Circuit With IC TDA7294

Power Amplifier TDA7294 is a power amplifier with IC Power Amplifier is a mono 100W Class AB operation of OCL.

The power supply circuit. Positive, negative, and ground. Usually, we use the power supply circuit to + /-25V to + /-35V at 100W RMS will be used to heat sufficiently.

After many members have already made the TDA7294 as I know, with a sound quality that is the very gods or Hi-End itself.

Several days before the member’s PM to me saying that I had an amplifier using IC TDA7294 to have more of the same. Higher power. And low heat.

Achieved by increasing the voltage raising circuit For the more, it means high power and high heat up. Today I have come across. I use IC TDA7294 circuit at the time.

In-Home Use amplifier circuit is a Class G amplifier with low power consumption, resulting in the loss of a 20V DC power less.

And when you’re driving a high-power random access is party to a rhythm. Principles to do it. I took out a membership you can do is try to build up a bit.

We provides PCB both top and bottom side for you.

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3 Watt stereo amplifier circuit

3 Watt stereo amplifier circuit using MAX 7910 IC. The MAX9710 a stereo audio power amplifier IC capable of delivering 3Watts of out put to 4 Ohm loads. MAX9710 can be operated from a single 4.5V to 5.5V power supply , makes it ideal for hand held applications.The IC for 3 Watt stereo amplifier circuit also features thermal overload protection.

Circuit Schematics 3 Watt  Stereo Amplifier MAX 7910 

3 Watt stereo amplifier circuit 

This 3 Watt stereo amplifier circuit  is suitable for small power audio devices such as radio sets and portable CD players. 5 V DC power supply is used for powering the 3 Watt stereo amplifier circuit. 6V battery with an IN 4007 diode series to the positive terminal of it can also be used instead of 5 V DC supply. The 3 Watt stereo amplifier circuit will get a supply voltage approximately 5 V after 0.7 V voltage drop across diode.

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High Voltage 3 Watt Audio Power Amplifier Circuit

The LM4954 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 2.4 Watts of continuous average power to an 8 BTL load with less than 1% THD+N from a 7V_DC power supply.

Boomer audio power amplifiers are designed specifically to provide high quality output power with a minimal number of external components. The LM4954 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for lower-power portable applications where minimal space and power consumption are primary requirements.

Circuit   Diagram:

 High Voltage 3 Watt Audio Power Amplifier Circuit Diagram

The LM4954 features a low-power consumption global shutdown mode which is achieved by driving the shutdown pin with logic low. Additionally, the LM4954 features an internal thermal shutdown protection mechanism.

The LM4954 contains advanced pop & click circuitry which eliminates noises that would otherwise occur during turn-on and turn-off transitions.

The LM4954 is unity-gain stable and can be configured by external gain-setting resistors.

Key Specification:

Wide Power Supply Voltage Range	2.7 <= VDD <= 9V
Output Power: VDD = 7V, 1% THD+N	2.4W (typ)
Quiescent power supply current	3mA (typ)
PSRR: VDD = 5V and 3V at 217Hz	80dB (typ)
Shutdown power supply current	0.01µA (typ)

 

Features:

No output coupling capacitors, snubber networks or bootstrap capacitors required

Unity gain stable

Externally configurable gain

Ultra low current active low shutdown mode

BTL output can drive capacitive loads up to 100pF

"Click and pop" suppression circuitry

2.7V - 9.0V operation

Available in space-saving microSMD package

Applications

Mobile Phones

PDAs

Source:national

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Stereo Power Amplifier Circuit based on BA5417

BA5417 is a stereo amplifier IC with a lot of good features like thermal shut down, standby function, soft clipping, wide operating voltage range etc. The IC can deliver 5W per channel into 4 ohm loud speakers at 12V DC supply voltage. The BA5417 has excellent sound quality and low THD (total harmonic distortion) around 0.1% at F=1kHz; Pout=0.5W.

Stereo Power Amplifier  Circuit diagram :

Setup and working of this stereo power amplifier circuit is somewhat similar to the BA5406 based stereo amplifier circuit published previously. C10 and C11 are DC decoupling capacitors which block any DC level present in the input signals. C2 and C6 couples the amplifiers left and right power outputs to the corresponding loud speakers. C1 and C5 are bootstrap capacitors.

Bootstrapping is a method in which a portion of the amplifiers is taken and applied to the input. The prime objective of bootstrapping is to improve the input impedance. Networks R1,C3 and R2,C7 are meant for improving the high frequency stability of the circuit. C4 is the power supply filter capacitor. S1 is the standby switch. C8 is a filter capacitor. R3 and R4 sets the gain of the left and right channels of the amplifier in conjunction with the 39K internal feedback resistors.

Note :

• Supply voltage range of BA5417 is from 6 to 15V DC.
• The recommended supply voltage for this circuit is 12V DC.
• The power supply must be well regulated and filtered.
• BA5417 requires a heatsink.
• The circuit can be assembled on a perf board without much degradation in performance.

Source : http://www.ecircuitslab.com/2012/07/stereo-power-amplifier-circuit-based-on.html

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60W Bass Amplifier

This design adopts a well established circuit topology for the power amplifier, using a single-rail supply of about 60V and capacitor-coupling for the speaker(s). The advantages for a guitar amplifier are the very simple circuitry, even for comparatively high power outputs, and a certain built-in degree of loudspeaker protection, due to capacitor C8, preventing the voltage supply to be conveyed into loudspeakers in case of output transistors failure.The preamp is powered by the same 60V rails as the power amplifier, allowing to implement a two-transistors gain-block capable of delivering about 20V RMS output. This provides a very high input overload capability.

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6 12 Volt audio amplifier

The above is an amplifier circuit using supply voltages from 6 volts DC to 12 Volt DC. Power output of the amplifier is quite low with only 1 Watt 8 ohm impedance. You can apply this to the audio signal amplifiers that require strengthening are not so large as in the pocket radio.

Part List :
R1 =  100K
R2 = 39R
R3 = 100R
C1 = 100nF
C2 = 100uF
C3 = 100uF
C4 = 100uF
C5 = 470uF
C6 = 100nF
C7 = 68pF
C8 = 1nF
C9 = 47uF
IC = SFC2790C

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Simple 30 Watt VHF Amplifier by using 2SC1946A

The 30 watt amplifier schematic shown below provides an appropriate power boost with an input of 4 watt up to 6 watts. The circuit is designed to cover 88-108MHz FM Broadcast Band. However, the circuit is very stable at my place and provides a clean-output through seven (7) element Butter-worth low-pass filter.

Circuit Diagram:

Notes:
The heart of the circuit is 2SC1946A VHF RF power transistor. The transistor is specifically designed for operation in frequencies up to 175 MHz, with very good results. As you can see, the power line is well decoupled. The amplifier current can be over 5 amps. All the coils are made from 16gauge laminated wire (or Silver copper wire can do best) and the RFC can be of HF toroid core (as shown in the picture) or 6 holes ferrite bead.C3 and R1 forms snubber circuit while R2 and C6 prevent the amplifier from self-oscillation at VHF, sometimes you need to add 180 ohms in parallel with L7.That will cause the amplifier to dissipate UNDESIRABLE VHF thereby reducing spurious level.

The photo below is 60Watts VHF power amplifier using the above circuit. Two of 2SC1946A transistors are arranged at 90 degrees to each other and their outputs are combined using "Power Combiner Network”. It is quite difficult to combine powers at VHF and UHF bands.

However, I recommend that hobbies should stick to single power design due to its complicity and large rate of INTERFERENCE. (in attempt to go for double transistors which involves power combiner network). Since the two amplifiers are operating in different phase (out of phase).

Tuning:
Tuning of the amplifier is not hard at all. You just have to connect the output to a good antenna with a transmission line (RG214) of 50 ohms. First match the output network, and then do the same to the input network for a maximum power output. By way of adjustment, you can increase the output at its operating frequency.

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50W Power Amplifier Using STK084

This is the circuit diagram of 50W power amplifier circuit which built based on single power amplifier chip of STK084. Its an well-known old IC for audio frequency (AF) amplifier.

50W Power Amplifier Circuit Diagram

This circuit requires dual polarity / split power supply with maximum supply of ± 50. The recommended supply is ± 35 / 2-3A DC current. You may use this split power supply circuit for the amplifier. Use 28V center tap transformer to get about ± 36V output.

Technical Details:

Power output: 50W
RL : 8 Ohm
TDH : 0.2 %
Rin : 52K
Gain : 26.4 dB
Noise : 0.3 mV

Take a note that heatsink is required to be mounted on the power IC since it will going to hot when operated and deliver high power output (high audio volume level).

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100W Guitar Power Amplifier Rise

The power amp board has remained unchanged since it was first published in 2002. It definitely is not broken, so there is no reason to fix it. The picture below shows a fully assembled board (obtainable as shown as M27). Using TIP35/36C transistors, the output stage is deliberately huge overkill. This ensures reliability under the most arduous stage conditions. No amplifier can be made immune from everything, but this does come close.

Guitar Power Amplifier Board

The power amp (like the earlier version) is loosely based on the 60 Watt amp historically in the past published (Project 03), but its increased gain to match the preamp. Other modifications include the short circuit protection - the tiny groups of parts next to the bias diodes (D2 and D3). This new version is not massively different from the original, but has adjustable bias, and is designed to provide a "constant current" (i.e. high impedance) output to the speakers - this is achieved using R23 and R26. Note that with this arrangement, the gain will change depending on the load impedance, with lower impedance giving lower power amp gain. This is not a controversy, so may safely be ignored.

Ought to the output be shorted, the constant current output characteristic will provide an preliminary level of protection, but is not foolproof. The short circuit protection will limit the output current to a comparatively safe level, but a sustained short will cause the output transistors to fail if the amp is driven hard. The protection is designed not to operate under normal conditions, but will limit the peak output current to about 8.5 Amps. Under these conditions, the internal fuses (or the output transistors) will probably blow if the short is not detected in time.

Figure 2 - Power Amplifier

Figure two shows the power amp PCB parts - except for R26 which doesnt mount on the board. See Figure 1B to see where this ought to be physically mounted. The bias current is adjustable, & ought to be set for about 25mA dormant current (more on this later). The recommendation for power transistors has been changed to higher power devices. This will give improved reliability under sustained heavy usage.

As shown, the power transistors will have an simple time driving any load down to four ohms. In case you dont use the PCB (or are happy to mount power transistors off the board), you can use TO3 transistors for the output stage. MJ15003/4 transistors are high power, & will run cooler because of the TO-3 casing (lower thermal resistance). Watch out for counterfeits though! Theres plenty of other high power transistors that can be used, & the amp is tolerant of substitutes (as long as their ratings are at least equal to the devices shown). The PCB can accommodate Toshiba or Motorola 150W flat-pack power transistors with relative ease - in case you desired to go that way. TIP3055/2966 or MJE3055/2955 may even be used for light or ordinary duty.

At the input finish (as shown in Figure 1B), there is provision for an auxiliary output, & an input. The latter is switched by the jack, so you can use the "Out" & "In" connections for an outside effects unit. Alternatively, the input jack can be used to connect an outside preamp to the power amp, disconnecting the preamp.

The speaker connections permit up to 8 Ohm speaker cabinets (giving four Ohms). Do not use less than four ohm lots on this amplifier - it is not designed for it, & wont give reliable service!

All the low value (i.e. 0.1 & 0.22 ohm) resistors must be rated at 5W. The 0.22 ohm resistors will get warm, so mount them away from other parts. Needless to say, I recommend using the PCB, as this has been designed for optimum performance, and the amp gives an excellent account of itself. So nice in fact, that it may even be used as a hi-fi amp, and it sounds excellent. In case you were to make use of the amp for hi-fi, the bias current ought to be increased to 50mA. Ideally, you would use better (faster / more linear) output transistors as well, but even with those specified the amp performs well indeed. This is largely because they are run at comparatively low power, and the extreme non-linearity effects would expect with only transistors do not occur because of the parallel output stage.

Make positive that the bias transistor is attached to of the drivers (the PCB is laid out to make this simple to do). A some quantity of heat sink compound as well as a cable tie will do the job well. The diodes are there to protect the amp from catastrophic failure ought to the bias servo be incorrectly wired (or set for maximum current). All diodes ought to be 1N4001 (or 1N400? - anything in the 1N400x range is fine). A heat sink is not needed for any of the driver transistors.

The life of a guitar amp is a hard, and I recommend that you use the largest heat sink you can afford, since it is common to have elevated temperatures on stage (chiefly due to all the lighting), and this reduces the safety margin that normally applies for domestic equipment. The heat sink ought to be rated at 0.5° C/Watt to permit for worst case long term operation at up to 40°C (this is not unusual on stage).

Make sure that the speaker connectors are isolated from the chassis, to keep the integrity of the earth isolation parts in the power supply, & to make sure that the high impedance output is maintained.

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LM1875 – POWER AMPLIFIER 20 WATT

 

The LM1875 is a monolithic power amplifier offering very low distortion and high quality performance for consumer audio applications.

The LM1875 delivers 20 watts into a 4Ω or 8Ω load on ±25V supplies. Using an 8 load and ±30V supplies, over 30 watts of power may be delivered. The amplifier is designed to operate with a minimum of external components. Device overload protection consists of both internal current limit and thermal shutdown.

The LM1875 design takes advantage of advanced circuit techniques and processing to achieve extremely low distortion levels even at high output power levels. Other outstanding features include high gain, fast slew rate and a wide power bandwidth, large output voltage swing, high current capability, and a very wide supply range. The amplifier is internally compensated and stable for gains of 10 or greater.

Features
• Up to 30 watts output power
• AVO typically 90 dB
• Low distortion: 0.015%, 1 kHz, 20 W
• Wide power bandwidth: 70 kHz
• Protection for AC and DC short circuits to ground
• Thermal protection with parole circuit
• High current capability: 4A
• Wide supply range 16V-60V
• Internal output protection diodes
• 94 dB ripple rejection
• Plastic power package TO-220

LM1875 - POWER AMPLIFIER 20 WATT, link

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40 MHz Wideband RF Amplifier

This transmitter works, radio frequency range with a wideband frequency of 40 MHz.So you can use this with lots of electrical equipments


The circuit is consuming a total of 7 mA of current while the gain is in the measurement of 20 dB. All these values are due to the presence of a 12 V up to 15 V DC supply. The input and the output of the circuit are designed to be compatible with coaxial cables with complex resistance of 75 Ohms.

Part List

R1=75ohm
R2=10Kohm
R3-7=5.6Kohm
R4-5 =4.7Kohm
R6=820ohm
R8=470ohm
R9=2.2Kohm
R10=68ohm
C1-3=47nF 100V
C2-4=10nF 100V
C5-6=47nF 100V
Q1-2-3=AF125
J1-2=Jack BNC

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RF Amplifier circuit with 2SC1970 2N4427

RF power amplifier circuit of this work is based on the transistor 2SC1970 and 2N4427. The set output power of 88-108 MHz FM RF Amplifier With 2SC1970 is about 1.3W and the input driver is 30-50mW. RF driver amplifier circuit uses a 2N4427 and its power amplifier using a transistor 2SC1970.

At the time of the amplifier circuit tuning FM 88-108 MHz RF Amplifier With 2SC1970 should use the power meter / watt meter or SWR or RF field can also use the meter. RF amplifier circuit can work from the frequency of 88-108 MHz.

RF Amplifier

Circuit of 88-108 MHz FM RF Amplifier With RF 2SC1970 can radiate far enough. At the time of tuning you should use a 50 Ohm dummy load. For the input signal should be installed to regulate the VR level so as not to over-modulation (30-50mW).

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LM4990 2 Watt Audio Power Amplifier with Selectable Shutdown Logic Level

The LM4990 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 1.25 watts of continuous average power to an 8Ω BTL load and 2 watts of continuous average power (LD and MH only) to a 4Ω BTL load with less than 1% distortion (THD+N+N) from a 5VDC power supply. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4990 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement.

Circuit Diagram :

  2 Watt Audio Power Amplifier with Selectable Shutdown Logic Level

The LM4990 features a low-power consumption shutdown mode. To facilitate this, Shutdown may be enabled by either logic high or low depending on mode selection. Driving the shutdown mode pin either high or low enables the shutdown pin to be driven in a likewise manner to enable shutdown. The LM4990 contains advanced pop & click circuitry which eliminates noise which would otherwise occur during turn-on and turn-off transitions. The LM4990 is unity-gain stable and can be configured by external gain-setting resistors.

 Features

Available in space-saving packages: LLP, Exposed-DAP TSSOP, MSOP, and ITL

Ultra low current shutdown mode

Improved pop & click circuitry eliminates noise during turn-on and turn-off transitions

2.2 - 5.5V operation

No output coupling capacitors, snubber networks or bootstrap capacitors required

Unity-gain stable

External gain configuration capability

User selectable shutdown High or Low logic Level
Key Specification

Improved PSRR at 217Hz & 1KHz	62dB
Power Output at 5.0V, 1% THD+N, 4Ω (LD and MH only)	2W (typ)
Power Output at 5.0V, 1% THD+N, 8Ω	1.25W (typ)
Power Output at 3.0V, 1% THD+N, 4Ω	600mW (typ)
Power Output at 3.0V, 1% THD+N, 8Ω	425mW (typ)
Shutdown Current	0.1µA (typ)

Applications

• Mobile Phones
• PDAs
• Portable electronic devices

Datasheets

Source: www.national.com

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