LM4756 National Semiconductor Corporation, LM4756 Datasheet
LM4756
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LM4756 Summary of contents
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... Dual 7W Audio Power Amplifier w/Mute, Standby and Volume Control General Description The LM4756 is a stereo audio amplifier capable of delivering 7W/channel at 10% distortion into a 4Ω or 8Ω load. The power amp has an internally set gain of 30dB. A 0V–5V DC controlled volume block provides 80dB of attenuation from input to line-out ...
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Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit www.national.com 20064401 2 ...
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... IHF - A Weighting Filter R = 25Ω IN IHF - A Weighting Filter R = 25Ω −40˚C to +150˚C (Notes 3, 4) ≤ T −40˚C ≤ T ≤ +85˚C MAX A 15V to 28V 35˚C/W 1.5˚C/W A LM4756 Typical Limit (Note 8) (Note 140 ± ± ± ...
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... T )/θ or the number given in the Absolute Maximum Ratings, whichever is lower. For operating at case A JA Mute (Pin 10) Operating Condition “L” “H” or Open “L” “H” or Open 4 = 25˚C. A LM4756 Typical Limit (Limits) (Note 8) (Note 9) 70 0.8 V (max) 2.0 V (min) 0.8 V (max) 2.0 V (min) , θ ...
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Typical Performance Characteristics THD+N vs Frequency V = 18V 1W/Channel CC OUT R = 4Ω, 80kHz BW L THD+N vs Output Power V = 18V 1kHz 4Ω, 80kHz BW L Output Power vs ...
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Typical Performance Characteristics Power Dissipation vs Output Power Channel Separation vs Frequency Volume Attenuation vs DC Voltage www.national.com (Continued) 20064421 20064423 20064425 6 Power Dissipation vs Output Power 20064422 Attenuation vs Frequency 20064424 Supply Current vs Supply Voltage 20064437 ...
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... The IC is well protected with thermal shutdown and output AC short circuit protection. Mute Function The muting function of the LM4756 allows the user to mute the music going into the amplifier, providing over attenuation from input to output. The function is enabled by placing a logic “1” onto the mute pin, pin 10. To disable the function, allowing music to be passed to the output, a logic “ ...
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... Any noise that is coupled into the device is gained up by 40dB. FIGURE 3. Volume Pin Lowpass Filter Turn On/Off Characteristics In order to minimize turn on and off pops, the LM4756 should be powered up by using the sequence described below. Figure 4 shows the sequence for turn on and off. www.national.com ...
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... The explanation of how the circuit in Figure 5 works will be related to the timing waveforms in Figure 6. The circuit in Figure 5 protects the LM4756 from SOA violations by ensur- ing that the enabling of the standby function when music is playing will not quickly bring the biasing to ground before the input signal is smoothly attenuated through the volume func- tion ...
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... Table 1. Also note once again that most systems typically utilize a microprocessor or COP microcontroller to interface with the logic control functions of the LM4756. When a clean logic signal is used, as from a microcontroller, RC lowpass filtering is not required for the mute and standby functions. FIGURE 5. Turn-On/Off External Circuitry ...
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... Application Information FIGURE 6. Turn-On/Off External Circuitry Sequence Line Out The line out function for the LM4756 is intended to provide preamp output control for signal routing to an external power amplifier. An example of this would where the TV’s remote control provides volume control on the audio signals that may be sent to a home theater receiver. The line out amplifier is only able to drive high impedance loads like 2kΩ ...
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... National, θ Since convection heat flow (power dissipation) is analogous to current flow, thermal resistance is analogous to electrical resistance, and temperature drops are analogous to voltage drops, the power dissipation out of the LM4756 is equal to the following: 20064431 The thermal resistance, θ ...
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... It is typical to use capacitor values that are a factor of 100 different from each other to minimize interaction with each other. The LM4756 should be bypassed with 0.1µF ceramic and 100µF tantalum capacitors for optimum performance. The 100µF tantalum can be replaced with an electrolytic, but the bypassing per- formance of the tantalum will be better ...
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... Application Information LM4756 REFERENCE BOARD ARTWORK Composite Layer Top Layer www.national.com (Continued) 20064441 20064440 14 Silk Layer 20064442 Bottom Layer 20064443 ...
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... Electrolytic / 35V 20% Electrolytic / 35V Standard Diode 1W Zener Diode SPDT (on-on) Switch Non-Switched PC Mount PCB Banana Jack - BLACK PCB Banana Jack - RED 2N3904 Small Signal transistor in TO-92 package 15 lead TO-220 Power Socket or 15 Comment 1/4 Watt 1/4 Watt 1/4 Watt 1/4 Watt 1/4 Watt 1/4 Watt 1/4 Watt RCA Jack LM4756 IC www.national.com ...
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... Physical Dimensions unless otherwise noted www.national.com inches (millimeters) Staggered 15 Lead Non-Isolated TO-220 Package Order Number LM4756TA See NS Package Number TA15A 16 ...
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... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. inches (millimeters) unless otherwise noted (Continued) Staggered 15 Lead Non-Isolated TO-220 Package with 90 degree lead bend Order Number LM4756TA Spec. LB10 See NS Package Number TA15D 2. A critical component is any component of a life support device or system whose failure to perform ...