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PDF LM4928 Data sheet ( Hoja de datos )
| Número de pieza | LM4928 | |
| Descripción | 1.2 Watt Stereo Fully Differential Audio Amplifier | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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www.DataSheet4U.com
February 2006
LM4928
1.2 Watt Stereo Fully Differential Audio Amplifier with RF
Suppression and Shutdown Low
General Description
The LM4928 is an stereo fully differential stereo audio power
amplifier primarily designed for demanding applications in
mobile phones and other portable communication devices. It
is capable of delivering 1.2 watts of continuous average
power to a 8Ω load with less than 1% distortion (THD+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 LM4928 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption is a primary re-
quirement.
The LM4928 features a low-power consumption shutdown
mode. To facilitate this, shutdown may be enabled by logic
low. Additionally, the LM4928 features an internal thermal
shutdown protection mechanism.
The LM4928 contains advanced pop & click circuitry which
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
Key Specifications
j Improved PSRR at 217Hz
90dB (typ)
j Output Power at 5.0V @ 1% THD+N (8Ω) 1.2W (typ)
j Output Power at 3.0V @ 1% THD+N (8Ω)400mW (typ)
j Shutdown Current
0.1µA (typ)
Features
n RF Suppression Circuitry
n Fully differential amplification
n Available in space-saving micro SMD and LLP packages
n Ultra low current shutdown mode
n Can drive capacitive loads up to 100pF
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 2.4 - 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
Applications
n Mobile phones
n PDAs
n Portable electronic devices and accessories
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2006 National Semiconductor Corporation DS201600
www.national.com
1 page  
Electrical Characteristics VDD = 3V (Notes 1, 2)
The following specifications apply for VDD = 3V, AV = 1, and 8Ω load unless otherwise specified. Limits apply for TA =
25˚C. (Continued)
Symbol
Parameter
Conditions
Po
THD+N
PSRR
CMRR
VOS
VSDIH
VSDIL
SNR
TWU
Output Power
Total Harmonic Distortion + Noise
Power Supply Rejection Ratio
Common-Mode Rejection Ratio
Output Offset
Shutdown Voltage Input High
Shutdown Voltage Input Low
Signal-to-Noise Ratio
Wake-up time from Shutdown
THD = 1% (max); f = 1 kHz
RL = 4Ω
RL = 8Ω
THD = 10% (max); f = 1 kHz
RL = 4Ω
RL = 8Ω
Po = 0.25Wrms; f = 1kHz
Vripple = 200mV sine p-p
f = 217Hz (Note 8)
f = 1kHz (Note 8)
f = 217Hz, VCM = 200mVpp
VIN = 0V
PO = 0.4W, f = 1kHz
Cbypass = 1µF
LM4928
Typical
Limit
(Note 6)
(Note 7)
0.55
0.40
0.68
0.50
0.05
90
90
70 50
4 18
1.4
0.4
105
9
Units
(Limits)
W
W
%
dB
dB (min)
mV (max)
V
V
dB
ms
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: 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 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX = (TJMAX – TA) / θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4928, see power
derating curve for additional information.
Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor.
Note 5: Machine Model, 220pF – 240pF discharged through all pins.
Note 6: Typicals are measured at 25˚C and represent the parametric norm.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: Inputs are AC terminated to GND.
Note 9: When driving 4Ω loads from a 5V power supply, the LM4928SD must be mounted to a circuit board with the exposed-DAP area soldered down to at least
4in2 plane of 1oz, copper.
Note 10: Data taken with BW = 80kHz and AV = 1 except where specified.
Note 11: Maximum Power Dissipation (PDMAX) in the device occurs at an output power level significantly below full output power. PDMAX can be calculated using
Equation 4 shown in the Application section. It may also be obtained from the Power Dissipation graphs.
External Components Description
(Figure 1)
Components
1. CS
2. CB
3. Ri
4. Rf
Functional Description
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
section for information concerning proper placement and selection of the supply bypass capacitor.
Bypass pin capacitor which provides half-supply filtering. Refer to the Power Supply Bypassing section for
information concerning proper placement and selection of CB.
Inverting input resistance which sets the closed-loop gain in conjunction with Rf.
External feedback resistance which sets the closed-loop gain in conjunction with Ri.
5 www.national.com
5 Page 
Typical Performance Characteristics (Note 10) (Continued)
Power Derating Curve (SD Package)
fin = 1kHz, RL = 8Ω
Power Derating Curve (SD Package)
fin = 1kHz, RL = 4Ω
20160068
Power Derating Curve (TL Package)
fin = 1kHz, RL = 8Ω
20160067
20160066
11 www.national.com
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LM4928.PDF ] | |
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