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PDF LM4889 Data sheet ( Hoja de datos )
| Número de pieza | LM4889 | |
| Descripción | 1 Watt Audio Power Amplifier | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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June 2003
LM4889
1 Watt Audio Power Amplifier
General Description
The LM4889 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 1 watt of continuous average power to an 8Ω BTL
load with less than 2% 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 LM4889 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 LM4889 features a low-power consumption shutdown
mode, which is achieved by driving the shutdown pin with a
logic low. Additionally, the LM4889 features an internal ther-
mal shutdown protection mechanism.
The LM4889 contains advanced pop & click circuitry to
eliminate noise which would otherwise occur during turn-on
and turn-off transitions.
The LM4889 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
j Improved PSRR at 217Hz, 5 - 3.3V
j Power Output at 5.0V & 2% THD
j Power Output at 3.3V & 1% THD
j Shutdown Current at 3.3 & 2.6V
75dB
1.0W(typ.)
400mW(typ.)
0.01µA(typ.)
Features
n Available in space-saving MSOP, SOIC, LLP, and micro
SMD packages
n Ultra low current shutdown mode (3.3 to 2.6V - 0.01µA)
n Can drive capacitive loads up to 500 pF
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 2.2 - 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
n Unity-gain stable
n External gain configuration capability
Applications
n Mobile Phones
n PDAs
n Portable electronic devices
Typical Application
20035801
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200358
www.national.com
1 page  
Typical Performance Characteristics
THD+N vs Frequency
at VDD = 5V, 8Ω RL, and PWR = 250mW
THD+N vs Frequency
at VDD = 3.3V, 8Ω RL, and PWR = 150mW
20035837
THD+N vs Frequency
at VDD = 2.6V, 8Ω RL, and PWR = 100mW
20035838
THD+N vs Frequency
at VDD = 2.6V, 4Ω RL, and PWR = 100mW
20035839
THD+N vs Power Out
at VDD = 5V, 8Ω RL, 1kHz
20035840
THD+N vs Power Out
at VDD = 3.3V, 8Ω RL, 1kHz
20035875
5
20035842
www.national.com
5 Page 
Application Information (Continued)
FIGURE 2. Higher Gain Audio Amplifier
20035824
The LM4889 is unity-gain stable and requires no external
components besides gain-setting resistors, an input coupling
capacitor, and proper supply bypassing in the typical appli-
cation. However, if a closed-loop differential gain of greater
than 10 is required, a feedback capacitor (C4) may be
needed as shown in Figure 2 to bandwidth limit the amplifier.
This feedback capacitor creates a low pass filter that elimi-
nates possible high frequency oscillations. Care should be
taken when calculating the -3dB frequency in that an incor-
rect combination of R3 and C4 will cause rolloff before
20kHz. A typical combination of feedback resistor and ca-
pacitor that will not produce audio band high frequency rolloff
is R3 = 20kΩ and C4 = 25pf. These components result in a
-3dB point of approximately 320kHz.
11 www.national.com
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet LM4889.PDF ] | |
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