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PDF LM4911 Data sheet ( Hoja de datos )
| Número de pieza | LM4911 | |
| Descripción | Stereo 40mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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July 2002
LM4911
Stereo 40mW Low Noise Headphone Amplifier with
Selectable Capacitive Coupled or OCL Output
General Description
The LM4911 is an stereo audio power amplifier capable of
delivering 40mW per channel of continuous average power
into a 16Ω load or 25mW per channel into a 32Ω load at 1%
THD+N from a 3V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4911 does not require
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems. In addition, the
LM4911 may be configured for either single-ended capaci-
tively coupled outputs or for OCL outputs (patent pending).
The LM4911 features a low-power consumption shutdown
mode and a power mute mode that allows for faster turn on
time with less than 1mV voltage change at outputs on re-
lease. Additionally, the LM4911 features an internal thermal
shutdown protection mechanism.
The LM4911 is unity gain stable and may be configured with
external gain-setting resistors.
Key Specifications
n PSRR at 217 Hz and 1kHz
65dB (typ)
n Output Power at 1kHz with VDD = 2.4V, 1% THD+N into
a 16Ω load
25mW (typ)
n Output Power at 1kHz with VDD = 3V, 1% THD+N into a
16Ω load
40mW (typ)
n Shutdown Current
2.0µA (max)
n Output Voltage change on release from Shutdown
VDD = 2.4V, RL = 16Ω (C-Coupled)
1mV (max)
n Mute Current
100µA (max)
Features
n OCL or capacitively coupled outputs (patent pending)
n External gain-setting capability
n Available in space-saving MSOP package
n Ultra low current shutdown mode
n Mute mode allows fast turn-on (1ms) with less than 1mV
change on outputs
n 2V - 5.5V operation
n Ultra low noise
Applications
n Portable CD players
n PDAs
n Portable electronics devices
Block Diagram
FIGURE 1. Block Diagram
20031478
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200314
www.national.com
1 page  
Electrical Characteristics VDD = 2.4V (Notes 1, 2)
The following specifications apply for VDD = 2.4V, RL = 16Ω, and CB = 4.7µF unless otherwise specified. Limits apply to TA =
25˚C.
Symbol
Parameter
Conditions
LM4911
Typ Limit
(Note 6) (Note 7)
Units
(Limits)
IDD Quiescent Power Supply Current VIN = 0V, IO = 0A
ISD Shutdown Current
VSHUTDOWN = GND
IM Mute Current
VMUTE = VDD, C-Coupled
THD = 1%; f = 1kHz
1.5 3 mA (max)
0.1 2.0 µA(max)
40 80 µA(max)
PO Output Power
R = 16Ω 25 mW
R = 32Ω
12
VNO
PSRR
TWU
VOSD
Output Noise Voltage
BW = 20 Hz to 20kHz, A-weighted
10
µV
Power Supply Rejection Ratio
Wake Up Time from Shutdown
Output Voltage Change on
Release from Shutdown
VRIPPLE = 200mV sine p-p
OCL
C-Coupled, CO = 100µF
C-Coupled, CO = 100µF
65 dB
0.5
s
2
1 mV (max)
TUM Time to Un-Mute
C-Coupled, CO = 100µF
0.01
0.02
s (max)
Note 1: All voltages are measured with respect to the GND 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 LM4911, see
power derating currents for more 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: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
Note 9: 10Ω Terminated input.
External Components Description (Figure 2)
Components
1. RI
2. CI
3. Rf
4. CS
5. CB
6. Co
Functional Description
Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a
high-pass filter with Ci at fc = 1/(2πRiCi).
Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a
high-pass filter with Ri at fc = 1/(2πRiCi). Refer to the section Proper Selection of External Components, for
an explanation of how to determine the value of Ci.
Feedback resistance which sets the closed-loop gain in conjunction with Ri.
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 section, Proper Selection of Proper
Components, for information concerning proper placement and selection of CB
Output coupling capacitor which blocks the DC voltage at the amplifier’s output. Forms a high pass filter with
RL at fo = 1/(2πRLCo)
5 www.national.com
5 Page 
Typical Performance Characteristics (Continued)
Channel Seperation
Channel Seperation
Channel Seperation
200314A1
Channel Seperation
200314A2
Channel Seperation
20031417
Channel Seperation
20031419
20031418
11
20031416
www.national.com
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet LM4911.PDF ] | |
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