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PDF LM4913MM Data sheet ( Hoja de datos )
| Número de pieza | LM4913MM | |
| Descripción | 2W Monaural/ 90mW Stereo Headphone Audio Amplifier | |
| Fabricantes | National Semiconductor | |
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December 2002
LM4913
2W Monaural, 90mW Stereo Headphone Audio Amplifier
General Description
The unity-gain stable LM4913 is both a mono differential
output (for bridge-tied loads, or BTL) audio power amplifier
and a single-ended (SE) stereo headphone amplifier. Oper-
ating on a single 5V supply, the mono BTL mode delivers 2W
(typ) to a 4Ω load (Note 1) at 0.3% THD+N. In SE stereo
mode, the amplifier will deliver 90mW to 32Ω loads. The
LM4913 features circuitry that suppresses output transients
("clicks and pops").
The LM4913 is designed for notebook and other handheld
portable applications. It delivers high quality output power
from a surface-mount package and requires few external
components. The LM4913 is pin and functionally compatible
with the TPA0213.
Other features include an active-low micro-power shutdown
mode and thermal shutdown protection.
The LM4913 is available a space efficient 10-lead exposed-
DAP TSSOP package.
Note 1: When operating on a 5VDC supply, an LM4913MH that has been
properly mounted to a circuit board will deliver 2W into 4Ω. See the Applica-
tion Information sections for further information concerning PCB layout sug-
gestions to maximize the LM4913MH’s output power with a 4Ω load.
Key Specifications
j BTL output power (RL = 4Ω)
VDD = at 3.0V, THD = 1%
660mW (typ)
VDD = at 5.0V, THD = 0.3%
2W (typ)
j SE output power (RL = 32Ω and THD = 0.1%)
VDD = at 3.0V
33mW (typ)
VDD = at 5.0V
90mW (typ)
j Micro-power shutdown supply current
1µA (typ)
jPSRR (@ 1kHz, 2.9V ≤ VDD ≤
5.1V, (Fig. 1))
BTL
SE
52dB (typ)
62dB (typ)
Features
n Advanced "click and pop" suppression circuitry
n Stereo headphone amplifier mode
n Low current micro-power shutdown mode
n Thermal shutdown protection circuitry
n 2.5V to 5.5V operation
n Unity-gain stable
n Gain set with external resistors
n Space-saving exposed-DAP TSSOP package
Applications
n PDAs
n Cellular phones
n Handheld portable electronic devices
Connection Diagram
Top View
Order Number LM4913MH
See NS package Number MXF10A
200617A0
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200617
www.national.com
1 page  
Electrical Characteristics: Bridged-Mode Operation (VDD = 3V) (Notes 4, 9)
The following specifications apply for the circuit shown in Figure 1, RL = 4Ω, and a measurement bandwidth of 20Hz to
80kHz, unless otherwise specified. Limits apply for TA = 25˚C.
Symbol
Parameter
Conditions
PO
THD+N
VON
Output Power (Note 11)
Total Harmonic Distortion + Noise
Output Voltage Noise
THD = 1% (max); f = 1kHz (Note
12)
RL = 4Ω (THD = 0.1%)
f = 1kHz
RL = 4Ω, PO = 500mW
CB = 0.47µF, 20Hz < f < 20kHz
LM4913
Typical
Limit
(Note 9)
(Notes 10,
11)
660
Units
(Limits)
W
0.2 %
21 µVRMS
Electrical Characteristics: SE Operation (VDD = 3V) (Notes 4, 9)
The following specifications apply for the circuit shown in Figure 1, RL = 4Ω, and a measurement bandwidth of 20Hz to
80kHz, unless otherwise specified. Limits apply for TA = 25˚C.
Symbol
Parameter
Conditions
PO
THD+N
VON
Output Power (Note 11)
Total Harmonic Distortion + Noise
Output Voltage Noise
THD+N = 0.1%, f = 1kHz, RL =
32Ω
f = 1kHz
RL =32Ω, PO = 30mW
CB = 0.47µF, 20Hz < f < 20kHz
LM4913
Typical
Limit
(Note 9)
(Notes 10,
11)
33 30
0.1
12
Units
(Limits)
mW
%
µVRMS
Note 2: An LM4913MH that has been properly mounted to a circuit board with a copper heatsink area of at least 2in2 will deliver 2.1W into 4Ω.
Note 3: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 4: 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 5: 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 LM4913, see power derating
curves for additional information.
Note 6: Human body model, 100pF discharged through a 1.5kΩ resistor.
Note 7: Machine Model, 220pF–240pF discharged through all pins.
Note 8: The given θJA is for an LM4913 packaged in an MXF10A with the Exposed-DAP soldered to an exposed 2in2 area of 1oz printed circuit board copper.
Note 9: Typicals are measured at 25˚C and represent the parametric norm.
Note 10: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 11: Datasheet minimum and maximum specification limits are guaranteed by design, test, or statistical analysis.
Note 12: Output power is measured at the amplifier’s package pins.
Note 13: When driving 4Ω loads and operating on a 5V supply, the LM4913MH must be mounted to a circuit board that has a minimum of 2.5in2 of exposed,
uninterrupted copper area connected to the MH package’s exposed DAP.
Note 14: See Application Information section "Single-Ended Output Power Performance and Measurement Considerations" for more information.
5 www.national.com
5 Page 
Application Information (Continued)
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is
critical for low noise performance and high power supply
rejection. Applications that employ a 5V regulator typically
use a 10µF in parallel with a 0.1µF filter capacitors to stabi-
lize the regulator’s output, reduce noise on the supply line,
and improve the supply’s transient response. However, their
presence does not eliminate the need for a local 0.47µF
tantalum bypass capacitance connected between the
LM4913’s supply pins and ground. Do not substitute a ce-
ramic capacitor for the tantalum. Doing so may cause oscil-
lation.
Keep the length of leads and traces that connect capacitors
between the LM4913’s power supply pin and ground as
short as possible. Connecting a 0.47µF capacitor, CB, be-
tween the BYPASS pin and ground improves the internal
bias voltage’s stability and improves the amplifier’s PSRR.
The PSRR improvements increase as the bypass pin ca-
pacitor value increases. Too large, however, increases
turn-on time and can compromise the amplifier’s click and
pop performance. The selection of bypass capacitor values,
especially CB, depends on desired PSRR requirements,
click and pop performance (as explained in the section,
Proper Selection of External Components), system cost, and
size constraints.
MICRO-POWER SHUTDOWN
The LM4913 features an active-low micro-power shutdown
mode. When active, the LM4913’s micro-power shutdown
feature turns off the amplifier’s bias circuitry, reducing the
supply current. The logic threshold is typically VDD/2. The
low 0.1µA typical shutdown current is achieved by applying a
voltage to the SHUTDOWN pin that is as near to GND as
possible. A voltage that is greater than GND may increase
the shutdown current.
There are a few methods to control the micro-power shut-
down. These include using a single-pole, single-throw switch
(SPST), a microprocessor, or a microcontroller. When using
a switch, connect a 100kW pull-up resistor between the
SHUTDOWN pin and VDD and the SPST switch between
the SHUTDOWN pin and GND. Select normal amplifier op-
eration by opening the switch. Closing the switch applies
GND to the SHUTDOWN pin, activating micro-power shut-
down. The switch and resistor guarantee that the SHUT-
DOWN pin will not float. This prevents unwanted state
changes. In a system with a microprocessor or a microcon-
troller, use a digital output to apply the active-state voltage to
the SHUTDOWN pin.
HEADPHONE (SINGLE-ENDED) AMPLIFIER
OPERATION
BTL/SE [Mono (BTL)/Stereo (SE)] Function
Applying a voltage greater than 0.9VDD to the LM4913’s
BTL/SE headphone control pin switches the amplifier’s op-
eration from mono BTL to stereo SE. Applying a voltage less
than 0.55VDD to the LM4913’s BTL/SE headphone control
pin switches the amplifier’s operation from stereo SE to
mono BTL.
Figure 3 shows how to control the LM4913’s headphone
function using four external resistors and a dual-switch ste-
reo headphone jack. External resistors R4 - R6 provide the
control voltages that are applied through the upper head-
phone jack switch. R6 and R7 provide a DC return path for
the SE coupling capacitors.
200617A1
FIGURE 3. Headphone Operation and BTL - SE Mode Switching
{Resume here and check other Fig. 3 below.} With no head-
phones connected to the headphone jack, the R5-R6 voltage
divider sets the voltage applied to the BTL/SE pin (pin 7) at
approximately 50mV (comfortably below the 0.55VDD logic-
low threshold). This 50mV tells the LM4913 to select the
signal applied to the MONO-IN input and places the LM4913
in mono BTL operation. When stereo SE operation is de-
sired, both headphone jack switches are opened with a
headphone plug. Opening the lower one allows R5 to apply
VDD to the BTL/SE pin. This switches the amplifier’s inputs
to the stereo signal. Opening the lower one breaks the
connection between AMP4’s output and the BTL speaker,
11 www.national.com
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| PDF Descargar | [ Datasheet LM4913MM.PDF ] | |
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