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PDF LM4938 Data sheet ( Hoja de datos )
| Número de pieza | LM4938 | |
| Descripción | Stereo 2W Audio Power Amplifiers | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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February 2005
www.DataSheet4U.com
LM4938
Stereo 2W Audio Power Amplifiers
with DC Volume Control and Selectable Gain
General Description
The LM4938 is a monolithic integrated circuit that provides
DC volume control, and stereo bridged audio power amplifi-
ers capable of producing 2W into 4Ω (Note 1) with less than
1.0% THD or 2.2W into 3Ω (Note 2) with less than 1.0%
THD.
Boomer® audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components. The LM4938 incorporates a
DC volume control, stereo bridged audio power amplifiers
and a selectable gain or bass boost, making it optimally
suited for multimedia monitors, portable radios, desktop, and
portable computer applications.
The LM4938 features an externally controlled, low-power
consumption shutdown mode, and both a power amplifier
and headphone mute for maximum system flexibility and
performance.
Note 1: When properly mounted to the circuit board, LM4938MH will deliver
2W into 4Ω. See Application Information section Exposed-DAP package
PCB Mounting Considerations for more information.
Note 2: An LM4938MH that has been properly mounted to the circuit board
and forced-air cooled will deliver 2.2W into 3Ω.
Key Specifications
n PO at 1% THD+N
n into 3Ω
n into 4Ω
n into 8Ω
n Single-ended mode - THD+N at 92mW into
32Ω
n Shutdown current
2.2W (typ)
2.0W (typ)
1.3W (typ)
1.0%(typ)
0.5µA (typ)
Features
n Improved click and pop circuitry virtually eliminates
noise during turn on/off transitions
n DC Volume Control Interface
n System Beep Detect
n Stereo switchable bridged/single-ended power amplifiers
n Selectable internal/external gain and bass boost
n Thermal shutdown protection circuitry
n Unity gain stable
Applications
n Flat Panel Displays
n Portable and Desktop Computers
n Multimedia Monitors
n Portable Radios, PDAs, and Portable TVs
Block Diagram
20095601
FIGURE 1. LM4938 Block Diagram
Boomer® is a registered trademark of NationalSemiconductor Corporation.
© 2005 National Semiconductor Corporation DS200956
www.national.com
1 page  
Electrical Characteristics for Single-Ended Mode Operation (Notes 7,
10) (Continued)
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Note 3: The θJA given is for an MXA28A package whose exposed-DAP is soldered to an exposed 2in 2 piece of 1 ounce printed circuit board copper.
Note 4: The θJA given is for an MXA28A package whose exposed-DAP is soldered to a 2in2 piece of 1 ounce printed circuit board copper on a bottom side layer
through 21 8mil vias.
Note 5: The θJA given is for an MXA28A package whose exposed-DAP is soldered to an exposed 1in 2 piece of 1 ounce printed circuit board copper.
Note 6: The θJA given is for an MXA28A package whose exposed-DAP is not soldered to any copper.
Note 7: All voltages are measured with respect to the ground pins, unless otherwise specified. All specifications are tested using the typical application as shown
in Figure 1.
Note 8: When driving 3Ω loads from a 5V supply the LM4938MH must be mounted to the circuit board and forced-air cooled.
Note 9: When driving 4Ω loads from a 5V supply the LM4938MH must be mounted to the circuit board.
Note 10: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given, however, the typical value is a good indication of device performance.
Note 11: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θ JA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX = (TJMAX − TA )/θJA. For the LM4938, TJMAX = 150˚C, and the typical junction-to-ambient thermal resistance for each package
can be found in the Absolute Maximum Ratings section above.
Note 12: Human body model, 100pF discharged through a 1.5kΩ resistor.
Note 13: Machine Model, 200pF – 220pF discharged through all pins.
Note 14: Typicals are measured at 25˚C and represent the parametric norm.
Note 15: Limits are guaranteed to National’s AOQL ( Average Outgoing Quality Level). Datasheet min/max specification limits are guaranteed by design, test, or
statistical analysis.
5 www.national.com
5 Page 
Typical Performance Characteristics (Continued)
PSRR vs Frequency
VDD = 3V, RL = 32Ω, Unterminated
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PSRR vs Frequency
VDD = 5V, RL = 8Ω, Terminated
20095655
PSRR vs Frequency
VDD = 5V, RL = 8Ω, Unterminated
200956B0
PSRR vs Frequency
VDD = 5V, RL = 32Ω, Terminated, SE
20095667
PSRR vs Frequency
VDD = 5V, RL = 32Ω, Unterminated, SE
20095668
Crosstalk vs Frequency
VDD = 3V, RL = 8Ω, PO = 570mW
20095669
11
20095605
www.national.com
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet LM4938.PDF ] | |
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