150 MW stereo output TPA122 is a stereo audio power amplifier component-

PC power supply compatible with 8-needle SOIC or 8-pin SOIC

PowerPad MSOP package can be transmitted

-The completely specify 3.3-V and 5-V operations, each channel 150 mw continuously square-meal power

-runs to 2.5 VΩ8-load. The amplifier gain is configured by the external configuration

Anti -jump circuit with two resistors per input channel does not require external compensation settings to 1 to internal mid -rail power generation.

Thermal protection and short circuit protection

When loading from 5V driver ω8, THD+N is 0.1%when packed and packaged on the surface, and less than 2%in the audio band in 20 MSOP Hertz to 20 kil kiji. For ω32-load, when THD+N is reduced -1 kHz, SOIC is less than 0.06%and less than 1%from 20 Hz to 20 kunhe audio bands. Ω is used for 10-k and lm4880 and LM4881 compatible pins load, THD+N's performance is 0.01%(SOIC) at 1kHz, and the performance in the frequency band of 20Hz is less than 0.02%to 20 kilo.

Application information

The gain setting the resistor, RF and RI set the gain of TPA122 through the resistor RF and RI according to the resistor RF and RI.

Assuming that TPA122 is a MOS amplifier, the input impedance is high. Therefore, although the noise in the circuit increases with the increase of the RF value, the input leakage current is often not a problem. In addition, the correct startup operation of the amplifier requires a certain range of radio frequency value. In summary, it is recommended that the effective impedance of the amplifier reverse node is set between 5 kΩ and 20 kΩ. Effective impedance is calculated in Formula 2.

For example, consider the input resistance of 20 kΩ and the feedback resistance of 20 kΩ. The gain of the amplifier is -1, and the effective impedance of the inverter end is 10 kΩ, which is within the scope of the recommendation.

For high -performance applications, metal film resistors are recommended because their noise levels are often lower than carbon resistors. When the RF value is greater than 50kΩ, the amplifier becomes unstable due to the inherent input capacitance of the magnetic pole and MOS input structure formed by RF. Therefore, the small compensation capacitors of about 5 PF should be placed in parallel with RF. In fact, this creates a low -pass filter network, which is defined in equivalent 3.

For example, if the RF is 100 kΩ and CF is 5 pF, then FC(Low -through) 318 kHz, far exceeding the audio range.

Input capacitor CI

In a typical application, an input capacitor CI is required to allow the amplifier to bias the input signal to the appropriate DC level to achieve the best job. In this case, CI and RI form a high -pass filter, and the angle frequency is determined by Formula 4.

The value of CI is important because it directly affects the bass (low -frequency) performance of the circuit. For example, RI is 20kΩ, and the specification requires low sound to be as low as 20Hz. Formula 4 is re -configured to Formula 5.

In this example, the CI is 0.4 μF, so you can choose the value from 0.47μF to 1 μF. Another consideration of the capacitor is from the input source via the input network (RI, CI) and feedback resistor (RF) to the leakage path of the load. This leakage current generates a DC offset voltage at the input terminal of the amplifier, thereby reducing the useful clean air, especially in high -gain applications ( gt; 10). Therefore, low leaks or ceramic capacitors are the best choice. When using a polarized capacitor, in most applications, the positive electrode of the capacitor should face the amplifier input because its DC level is maintained at VDD/2, which may be higher than the source DC level. Note that confirming the polarity of the capacitor in the application is very important.

Application information (continued) Power supply decoupling

TPA122 is a high -performance CMOS audio amplifier, which requires enough power to be coupled to ensure that the total output harmonic distortion (THD) is as low as possible as possible as possible Essence Power decoupling can also prevent the length of the length between the amplifier and the speaker. The best decoupling is achieved by using two different types of capacitors. These two capacitors are targeted at different types of noise on the power line. For a higher frequency of transients, peaks, or online numbers, a good low equivalent series resistance (ESR) ceramic capacitor (usually 0.1 μF) is placed in the position of the VDD lead as close to the device as possible. The effect is the best effect. Essence In order to filter a low -frequency noise signal, it is recommended to place a 10μF or larger aluminum electrolytic capacitor near the power amplifier.

Mid -track bypass container

Mid -orbit bypass electric container (CB) has several important functions. During the startup process, CB determines the rate of the amplifier start. This helps push the pop -up noise to the scope of sub -audio (so low that it can't hear). The second function is to reduce the noise generated by the power supply to the output drive signal. This noise comes from the mid -rail generated circuit inside the amplifier. The capacitor is powered by the 160-KΩ power supply inside the amplifier. In order to reduce the startup volatility as much as possible, the relationship between Formula 6 should be maintained.

For example, consider a circuit, where the CB is 1 μF, the CI is 1 μF, and the RI is 20KΩ. Insert these values 6, the result is: 6.25≤50 to meet the rules. In order to obtain the best THD and noise performance, it is recommended to use bypass electrical container CB, the value of 0.1-1-μF ceramics or low ESR capacitors.

Output coupling capacitor

In a typical single -power single -end (SE) configuration, an output coupling capacitor (CC) is needed DC current. Like the input coupling capacitor, the output coupling capacitor and load impedance form a high -pass filter controller controlled by equal 7.

From a performance perspective, the main disadvantage is that the typical small load impedance will make the low -frequency angle higher. The large CC value is required to pass the low frequency into the load. Taking the 68μF CC as an example, the load ranges from 32Ω to 47 kΩ. Table 1 summarizes the frequency response characteristics of each configuration.

Table 1. The impact of common load impedance on low -frequency output characteristics in SE mode

As shown in Table 1, the headset response is sufficient, and the line level (such as the three -dimensional family of the family) is also very good Essence

The output coupling capacitance required in the single power SE mode also applies additional restrictions on the selection of other components in the amplifier circuit. When the rules described earlier are still effective, add the following relationship

Use a low ESR capacitor

It is recommended to use low ESR capacitors throughout the application process. A real capacitor can simply model a resistor to a ideal capacitor. The beneficial impact of the capacitor in the circuit was minimized through the voltage of the resistor to the minimum. The lower the equivalent values of this resistor, the more actual the capacitor performs like an ideal capacitor.

5-v and 3.3-V operations

TPA122 design for running within the range of 2.5 V to 5.5 V. This data table provides a complete specification of 5-V and 3.3-V, because they are considered the two most common standard voltage. In terms of power bypass, gain settings, or stability, there are no special considerations of 3.3 V and 5 V operations. The most important consideration is the output power. Each amplifier in TPA122 can generate a maximum voltage swing of VDD –1V. This means that for 3.3V operations, when VO (PP) 2.3V begins, it begins to appear limited, and for 5V operations, VO (PP) 4V. Before the distortion became obvious, the reduced voltage swing then reduced the maximum output to the load.

DGN power board #8482; Packaging contains an exposed heat mold pad, which is designed to directly connect to the external radiator. When the thermal mold pad is directly welded to the printing circuit board (PCB), the PCB can be used as a radiator. In addition, by using the heat -passing hole, the thermal mold pad can be directly connected to the designPCB's floor or special heat sink structure.This design optimizes the heat transfer of integrated circuits (IC).

DGN packaging exposed heat mold pads are shown in Figure 1.