General description

lm4873 is an audio power amplifier connected to a double bridge. When connected to 5V power supply, it will provide 2.1W to 4 load (Note 1) or or 2.4W to 3 load (Note 2), less than 1.0%Thd+N. In addition, the headset input pin allows the amplifier to work in a single -end mode to drive the stereo earphones. The MUX control pins are input in the two sets of stereo amplifiers, allowing two optional amplifiers to close the loop response. The Boomer audio power amplifier is specifically to provide high -quality output power from the surface installation. It only requires very little external components. In order to simplify the audio system design, the LM4873 combines the dual -bridge speaker amplifier and the stereo earphones amplifier. LM4873 uses external control, low power consumption shutdown mode, stereo earphones amplifier mode and heat shutdown protection. It also uses circuit to reduce the click and banging when the device is turned on.

Note 1: LM4873MTE-1 has been correctly installed on the circuit board, which will provide 2.1W to 4 . Other software package options of LM4873 will provide 1.1W to 8 . For information, see the application information part of the LM4873MTE-1 use information.

Note 2: LM4873MTE-1 has been correctly installed on the circuit board and forced wind cooling will provide 2.4W to 3 .

Main specifications

N PO

input 3 (LM4873MTE-) 2.4W (typical)

Enter 4 (LM4873MTE-1) 2.1W (typical)

Enter 4 (LM4873MTE) 1.9W (typical)

Enter 8 (LM4873) 1.1W (Typical)

Single-end mode -THD+

75 MW to 32

0.5%(maximum value)

The shutdown current 0.7 μA (Typical value)

Features

Enter MUX control. Each channel has two independent input stereo headphones amplifiers mode click to pop up inhibitory circuit heat shutdown and protection circuit that can provide exposed DAPs that can be exposed. TSSOP和TSSOP包装

应用

多媒体监视器

便携式和台式计算机

便携式音频系统

[123 ]

Absolutely maximum rated value (Note 4)

Power voltage 6.0V

Storage temperature 65 ; C to+150 ; C

Input voltage 0.3V to VDD+0.3V

Gong Consumption (Note 14) Internal limited

ESD Sensitivity (Note 15) 2000V

Static discharge sensitivity (Note 16) 200V

Nacking temperature 150 ; C [C [C [ 123]

Smoom information

Small shape package

Qi phase (60 seconds) 215 ; c

Infrared (15 seconds) 220 ; C 123]

See AN-450 surface installation and its product reliability applicable to other welding surface methods installation equipment.

Thermal resistance

θjc (typical) -m16b 20 #730; c/w

θja (typical) -m16b 80 ; C/W

θjc (typical) -N16a 20 ; C/W

θja (typical) -N16A 63 ; C/W

θjc (typical) -mtc20 ; C/W

θja (typical) -mtc20 80 ; C/ W

θjc (typical) -mxa20a 2 ; c/w

θja (typical) -mxa20a 41 ; c/w (Note 5)

θja (Typical) -mxa20A 51 ; C/W (Note 6)

θja (Typical) -MXA20A 90 ; C/W (Note 7)

θjc (Typical)- Mxa28a 2 ; C/W

θja (typical) -mxa28a 41 ; C/W (Note 8)

θja (typical) -mxa28a 51 ; C/W. (Note 9)

θja (typical) -mxa28a 90 ; C/W (Note 10)

Retown

Temperature range

TMIN ≤TA ≤TMAX 40 ; C≤TA ≤ 85 ; C

Power voltage 2.0V ≤VDD ≤ 5.5V

The electrical characteristics of the entire integrated circuit (Note 3, 4) The following specifications are applicable to VDD 5V, unless there are other instructions. Applicable limit when TA 25 ° CEssence

The electrical characteristics of the bridge mode operation (Note 3, 4) below the specifications of VDD 5V, unless there are other regulations. TA 25 ° C. Applicable limit.

The electrical characteristics of the single -end operation (Note 3, 4) below the specifications of VDD 5V, unless there are other regulations. The limit at TA 25 ° C

Note 3: Unless there are other regulations, all voltages are measured relative to ground pins 2, 7 and 15.

Note 4: Absolutely maximum rated value indicates the limit of damage to the device. The work rated value indicates the conditions for the equipment operation, but does not guarantee specific performance restrictions. Electrical characteristics illustrate DC and AC electrical specifications under specific test conditions to ensure specific performance limit. This assumes that the device is within the scope of the working ratio. For parameters without restrictions, the specifications are not guaranteed. However, the given typical value is a good instructions for equipment performance.

Note 5: The θja given is used for MXA20A packaging, and its exposed DAP is welded to a exposed 2in2 1 ounce printing circuit board.

Note 6: θja given is suitable for a MXA20A packaging, and its exposed DAP is welded to an exposed 1IN2 1 ounce of printing circuit board.

Note 7: The θja given is used for MXA20A packaging, and its exposed DAP is not welded with any copper.

Note 8: θja given is suitable for a MXA28A packaging, and its exposed DAP welding is exposed to a 2IN2 1 ounce of printing circuit board.

Note 9: θja given is suitable for a MXA28A packaging, and its exposed DAP is welded to an exposed 1IN2 1 ounce of printing circuit board.

Note 10: The θja given is used for MXA28A packaging, and its exposed DAP is not welded with any copper.

Note 11: When loading from 5V power driver 3 load, LM4873MTE or LM4873MTE-1 must be installed on the circuit board and forced wind and cold (450 linear feet per minute).

Note 12: When loading from 5V power driver 4 in load, LM4873MTE or LM4873MTE-1 must be installed on the circuit board.

Note 13: The output power is measured at the device terminal.

Note 14: The maximum power consumption must be reduced at high temperature, and it is determined by TJMAX, θJa and environmental temperature TA. The maximum power consumption is pdmax (tjmax t a)/θJa. For LM4873, tjmax 150 ; C. For different packagingθjas, see the application information part or the absolute maximum rated part.

Note 15: Human model, 100 PF discharge through 1.5 k resistor.

Note 16: Machine model, 220 PF -240 PF Power electricity through all pins. 25 ; Cal represents typical parameter C.

Note 18: The limit is guaranteed to be national AOQL (the average factory quality level).

Note 19: When the actual load is connected to the amplifier, the static power supply current depends on the offset voltage.

Typical performance characteristics MTE (20 stitches) features

Note 20: These curves show the heat dissipation capacity of LM4873MTE at different ambient temperatures, giving it given These conditions: 500LFPM+JEDEC board: parts welded on the DAP TSSOP test board exposed by 1S2P 20 lead, and 500 linear feet per minute pass through it. Board information-copper size: 74x74mm, copper coverage: 100%(buried layer) and 12%(top/bottom), exposed 16 pores under DAP. 500LFPM+2.5in2: Welded parts into a copper plane of 2.5in2, 1OZ., and 500 linear feet per minute pass. 2.5in2: Welded the parts to 2.5in2, 1OZ. Copper plane. Unconnected: The parts are not welded and the wind is not forced.

Note 21: These curves show the cooling capacity of LM4835mte at different environmental temperatures at different environmental temperatures: 500LFPM+2in2: Welded parts to a 2in2, 1oz. On the copper plane, 500 linear feet per minute pass through. 2in2on bottom: This part is welded on the 2in2oz copper plane at the bottom of the PC plate through 218mil pass. 2in2: Welded parts to 2in2, 1OZ. Copper plane. 1in2: Welded parts to 1In2, 1OZ. Copper plane. Unconnected: The parts are not welded and the wind is not forced.

Application information

and LM4863's pins output compatibility of the pins of the pins and LM4863 are for the pins of the pins of and LM4863. Simplify the design of LM4873 LM4863: In addition to the four bottom pins of LM4873 extra functions, LM4873MT/MTE matches LM4863MT/MTE pin. (Note 22) Note 22: If LM4873 replaces LM4863 and does not use the MUX circuit, the LM4873 MUX control pin must be connected to VDD or GND

Each eachThere are two inputs in each passage. Which input of MUX control pin control is activity. If the logical input shown in the truth table, if MUX control is kept at a low level, enter 1 activation. If MUX control is kept at a high position, enter 2 activation. Figure 2 shows an example of the MUX control circuit. MUX input 1 is connected to a feedback network, which can increase low -frequency gain (bass enhancement). MUX input 2 is connected to a simple gain circuit. The example circuit has to balance the internal speaker MUX input 2 for line output or headset drive. In this case, MUX control and HP-IN tube feet will be connected together, so when the headset is inserted, the feedback network will automatically change. If the HP input and MUX are not connected to the control pin, the use of the example circuit to choose a bass enhancement for the user, so that the user can choose the bass enhancement in the HP state. Because MUX controls the switch between the two reverse inputs of the amplifier, changing the input signal source or feedback network, you may hear a click to convert from one MUX input to other. For example, in the example circuit above, if, when transition, the income is obviously different between the MUX state, and a click can be heard as the feedback network, so the income can be changed suddenly.

Exposure-DAP Installation Precautions

The exposure of the DAP package of LM4873MTE needs to pay special attention to thermal design. If the heat design problem is incorrect, the LM4873MTE of 4 will enter the hot shutdown state. The DAP exposed at the bottom of the LM4873MTE should be welded on the copper pad on the circuit board. The heat leads to the aircraft from the exposed DAP. If the copper plane is not on the top surface of the circuit board, the diameter is 0.013 inches or smaller 8 to 10 perforated applied to exposed DAP and aircraft. In order to obtain good thermal conductivity, the hole must be plated and welded.

It should be used to make heat from exposed. If the aircraft is on the same side of the circuit board and the exposed DAP, 2.5in2 is the minimum value of 5V to 4 If the minimum value of hot 2DAP on the plane is not equal to 5DAP. If the room temperature is higher than 25 degrees Celsius, it is a larger copper plane or the need to force the cold to keep the LM4873MTE knot temperature below the heating temperature (150 degrees Celsius). See the power reduction curve for LM4873mte for the amount of information. LM4873MTE needs to be forced to become 3 . Connected to the 2.5 -square -inch bare copper, the load is 3 and the ambient temperature is 25 ° C. 450 linear feet per minute make parts from being influenced by heating. At a higher environmental temperature, higher airflow speeds and/or larger copper areas need to be retained by the heat shutdown.

The exposed DAP TSSOP circuit board layout. 3 and 4 LayoutFor low impedance loads, the output power at the load is seriously dependent on the tracking resistance that depends on the output pin on LM4873. Output from LM4873MTE to the load connector should be as wide as possible. Any resistor in the output trajectory will reduce power consumption

Application information (continued)

Delivery the goods. For example, in 4 load and 0.1 track the resistance of each output end. The output power of the load is reduced from 2.1W to 2.0W output power. Under the condition of keeping the power supply voltage at full output, the power cord should be as wide as possible.

Network bridge configuration description

As shown in Figure 1, there are two pairs of computing amplifiers inside the LM4873, allowing several different amplifiers configurations. The gain of the first amplifier is external -configured, while the second amplifier is fixed in the unit gain and reversed configuration. The first amplifier of a closed -loop gain is to fix the resistor of the second amplifier that set the ratio of RF to RI to fix the resistor. Figure 1 shows the output of the amplifier 1 as the input of the amplifier 2, which causes the two regulators to generate the same size signal, but phase 180 ; Therefore, the channel of each IC is the average value 2*(RF/R i) through output+output and outA or+outB and OUTB. Configuration. The operation of the bridge is different from the classic single -end amplifier configuration, and the side of its load is grounded. The design of the bridge amplifier is configured in a single -end configuration, because it provides a driver load, which doubles the output swing of a specific power supply voltage. Four times the output power is possible compared to single -end amplifiers. This increase in the output power means that the amplifier is not limited or limited by current. To choose the closed -loop gain of the amplifier instead of over -cut waves, please refer to the design part of the audio power amplifier. The configuration of the bridge, such as the LM4873, has a second advantage compared to a single -end amplifier. Due to differential output,+outa, outa,+outb, and outB, partially pressed at half of the power supply, and there is no clear DC voltage on the load. In this way, there is no need to output the coupling capacitor required for a single power supply, a single -end amplifier configuration. If the output coupling container does not use the power supply partial pressure on the half -end configuration load, it will cause the internal IC power consumption and permanent power consumption speaker damage.

Power loss

Whether the power amplifier is a bridge or a single -end, in the design amplifier. Formula 1 illustrates the point voltage and driver specified load of the single -end amplifier working under a given power supply. PDMAX (VDD) 2/(2π2RL): Single -end (1) The direct consequence of the increase in power transmitted by the bridge amplifier to the load is the increase in internal power consumption. Formula 2 represents the maximum value workIn the same given conditions. PDMAX 4*(VDD) 2/(2π2RL): Bridge mode (2) Since LM4873 is a dual -channel power amplifier, according to the operating mode, the maximum internal power consumption is 2 times that of equations 1 or equation 2. Even if the power consumption increases significantly, LM4873 does not require heat dissipation. Power loss Depending on Formula 2, assuming 5V power and 8 load must not be greater than Formula 3 power consumption: pdmax (tjmax ta)/θJa (3) For M16A and MTC20 packages, θja 80 ; C/w.tjmax 150 ; clm4873 of θja 63 ; c/w.tjmax 150 ; Depending on the environmental temperature TA system environment, Formula 3 can be used to calculate the largest internal power packaging supported by integrated circuits. If the result of Formula 2 is greater than the formula 3, it will either reduce the power supply voltage, increase the load impedance, or reduce the ambient temperature. For the typical application of 5V power supply, 8 bridge load, without violating the maximum knot, provides a possible maximum ambient temperature and temperature of about 48 ° C. The premise is that the equipment runs near the maximum power consumption point. Package. Internal energy difference is a function of the output power. If the typical operation is not the temperature around the maximum power consumption point can increase. For the power consumption information of different output power, see the typical performance characteristic curve.

Power bypass

Like any power amplifier, the correct power bypass is essential to respond to low noise performance and high power supply. Capacitor positions on the bypass and power supply should be as close to the device as much as possible. The effect of this larger semi -power -supply bypass power container has been improved due to increased supply stability by half. The typical application uses a capacitor filter with a 5V regulator with 10 μF and 0.1 μF bypass. This does not mean to bypass LM4873. The choice of bypass electrical container, especially C B, depends on the required PSRR requirements. Please click with popular music performances, as described in this section, the selection, system cost and size limit of external components.

Shipping function

In order to reduce the power consumption LM4873 when not in use, it contains a closure of pins and is used for external shutdown amplifier's bias circuit. When there is a logic high -electricity on the stop pin, this closure function is turned off AM amplifier. The trigger point between the logic low level and the logic high level is usually half of the supply. It is best to provide VDD on the ground to provide the maximum equipment performance. By switching the shutdown pin to the VDD, LM4873 power current consumption will minimize the free mode. When the device's closing voltage is lower than the VDD, the typical value may be greater than the idle current of 0.7 μA. In any case, shutdown sales should be connected to a certain voltage to avoid unnecessary state changes. In many applications, the output of the microcontroller or microprocessor is used to control the shutdown circuit. The circuit provides fast and flatStable shutdown. Another solution is to combine the use of a single -throw switch with an external pull -up resistor. When the switch is turned off, the stop pins are grounded and enabled the amplifier. If the switch is cut off, the external pull RE

Application information (continued)

Sister will disable LM4873. This plan ensures that the shutdown will not float, thereby preventing unnecessary conditions.

HP-in function

LM4873 has a headset control pin, which can turn off the amplifier driver+OUTA and+OUTB in order to perform single-end operations, and the bridge connection loading is mute. Static current consumption is reduced when the IC is in a single -end mode. Figure 3 shows the use of single -power headset amplifiers to implement the LM4873 header -type telephone control function. R1 and R2 sorters set the voltage to HP-I-pin (pin 16) in the system. The voltage on this logic low HP-in pin is enabled by LM4873 and placed it in the bridge mode. The resistor R4 restricted current flows out of the underground headset amplifier when the music flows out from the HP-IN pin. The output coupling container protects the headset DC voltage by blocking the semi -power supply of the amplifier.

When there is no headset insertion system and IC is configured in the bridge mode, both loads are 0 volt DC potential. Because the HP-IN threshold is set to 4V, even if Ideally, the output width cannot cause a wrong single-end trigger. When a set of headphones is inserted into the system, the tactile and signal pins of the headset jack, the sterilizer R1 and R2 of the resistor set by the resistor set. The resistor R1 then pulled out the HP-I-pin and turned on the headset function. This will disable the side of the second amplifier, so the bridge connects the speaker mute. This is then the amplifier drives the headset, and its impedance is connected to the resistor R2 and R3. The impact of resistor R2 and R3 on the output driver capacity can ignore the typical impedance of the headset of the headset 32 u200bu200b It is also displayed in FIG. 3 is the electrical connection jack and plug of the headset. Three -line plugs are tip, ring, and SLEAVE. The cutting -edge and ring are signal transmission conductors, and Sleave is a public ground circuit. Each headset jack has a control needle contact, which is enough to indicate that the control user has inserted the plug into another operating mode. LM4873 can be used to drive a pair of bridges 8 speakers and one-to-32 headphones, and do not use HP-IN pins. In this case, HP-I cannot connect to the headset jack, but connect to a microprocessor or switch. By enabling the HP-in pin, the speaker can be mute. Correctly selecting external components In the application of integrated power amplifier, correct selection of external components is the key and systematic performance of optimization devices. For various external components combinations of LM4873, considering the component value must be used to maximize the overall quality of the system

LM4873 is a unified gain and stability, giving the designer the biggest system performance. LM4873 is used in low -gain configuration to minimize THD+N value, and maximum signal -to -noise ratio. Low -gain configuration requires a large input signal to obtain a given output power. The input signal is equal to or greater than 1 VRMS from the source of the audio edit decoder. For more complete information, please refer to the instructions for the correct selection of gain in Section Audio Power amplifier Design . In addition to income, one of the main factors is the closed bandwidth of the amplifier. To a large extent, bandwidth depends on the selection of external components as shown in Figure 1. Enter the coupling capacitance CI table A to limit the first -order high -pass filter of low -frequency response. Select this value according to the frequency response required by several different reasons

Application information (continued)

Click the pop -up circuit

lm4873 contains the circuit, which can be reduced to the maximum extent Start the transient or click sound. In this case, opening refers to the operation mode of the power supply or the device stopped. When the device is turned on, the amplifier is configured to a unit gain buffer. The internal current source increases the voltage of the bypass feet. Both input and output can track the voltage on the bypass. The device will keep the buffer mode until the bypass lead has reached half of the power supply voltage, 1/2 VDD. Once the bypass node is stable, the device will run completely, and the gain is set by the external resistor. Although the barrier current source cannot be modified, it can change the size of the circuit breaker to change the opening state of the device and the number of click and pop up . By increasing, the number of POP can be reduced. However, the balance of using a larger bypass container is the boot time of this device. The size of the circuit breaker has a linear relationship with the power -powered time. Here are some typical opening time of a given circuit weapon:

In order to eliminate the sound of click , all capacitors must be discharged before booting. The rapid opening/control of the device or shutdown function may cause the click sound circuit to not run completely, resulting in click and banging. In a single -end structure, the output coupling capacitor (CO) is particularly worthy of attention. This capacitor discharge through the internal 20 k the resistor. Relying on the size of C, the time constant can be relatively large. In order to reduce the transient in a single -end mode, the external 1 k –5 k the resistor can connect 20 k the resistor. The cost of using this resistor is to increase static current. The CI value will also reflect the persistent organic pollutants that are opened. Obviously, a certain CI size requires excessive attenuation at low frequencies. However, in many cases, the speaker is used for portable systems. Whether it is overall or external, there is a poor ability to reproduce from 100 Hz to 150 Hz below. In this case, using large input and output capacitors may not improve system performance. In most cases, the CI value is small, the range is 0.1 μF to 0.33 μF) When CB is equal to 1.0 μF, You should almost open the POPLESS without clicking. If the CI is greater than 0.33 μF, it may help increase the CB value. Again, it should be understood that increasing CB will have a longer -term booting time.

Application information (continued)

Note for empty -load design

If the output load of LM4873 is higher than 10K , LM4873 may appear at a high output level may appear at a high output level. Small oscillation. To prevent this oscillation, the power output is grounded. Audio power amplifier design 1W/8 bridge audio amplifier

In view of:

Power output: 1 WRMS

Load impedance: 8

Input level: 1 VRMS

Input impedance: 20 k

Bandwidth: 100 Hz 20 kHz ± 0.25 db

Designer must must First determine that the minimum supply track obtains the specified output power. The relationship between the relationship between the output power and the power supply voltage can be easily found in the typical performance characteristics part. The second method of determining the minimum support is to use the Vopeak required to calculate the Formula 3 calculation plus the voltage difference. Using this method, the minimum power supply voltage is (VOPEAK+(2*VOD)), where VOD is the curve of the typical performance characteristics inferred by the relationship between voltage drop and power supply voltage.

When the output power of 8 when the relationship between the relationship between the power supply voltage is loaded, the minimum power supply track is 3.9V. But because 5V is the standard power supply voltage in most applications, it is selected as the supply track. The additional power supply voltage creates a clean air, so that the LM4873 reappears a peak of more than 1W without generating it. At this time, the designer must ensure that the power consumption of the power supply and output impedance does not violate the explanation. Once the power consumption equation is solved, the required differential gain can be determined by equal 4.

According to Formula 4, the smallest AVD is 2.83; the use of AVD 3 due to the required input impedance is 20 k and AVD is 3, RF and RI's RI and RI The ratio is 1.5: 1 causes the distribution of RI 20 k , R F 30 K The final design step is to adjust the bandwidth requirements. A pair of 3 dB frequency points must be used. Five times from the pillar, the pillar reducing the response to a 0.17 decibel, which is better than the prescribed ± 0.25 dB. FL 100 Hz/5 20 Hz fH FH 20 kilus x 5 100 kilus As section external components section, the connection between RI and CI will create a high -pass filter.

ci≥1/(2π*20 k *20 Hz) 0.397μF; use 0.33 μF

High -frequency magnetic pole is expected to high -frequency pole FH and differential gain A.Virtual disk.When AVD 3 and FH 100kHz, the GBWP 150 kHz obtained is more than 3.5 trillion.This picture shows that if the designer needs to design a higher -differential amplifier LM4873, problems can still be used without taking up bandwidth.

Demonstration circuit layout

Here provides a demonstration circuit layout as an example of the circuit using LM4873.If LM4873MTE is used with this layout, the exposed DAP welding is received from the copper pad under the part.Thermal conductivity from the two large copper pads from the upper part of the template.This template provides enough heat dissipation capacity to allow LM4873MTE to output 1.9W to 4