National Semiconductor LM4915 Technical data
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LM4915
Pseudo-Differential Mono Headphone Amplifier with
Fixed 6dB Gain
LM4915 Pseudo-Differential Mono Headphone Amplifier with Fixed 6dB Gain
May 2003
General Description
The LM4915 is a pseudo-differential audio power amplifier
primarily designed for demanding applications in mobile
phones and other portable audio device applications with
mono headphones. It is capable of delivering 90 miliwatts of
continuous average power to a 32Ω BTL load with less than
1% distortion (THD+N) from a 3V
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4915 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement.
The LM4915 features a low-power consumption shutdown
mode. To facilitate this, Shutdown may be enabled by driving
the shutdown pin low. Additionally, the LM4915 features an
internal thermal shutdown protection mechanism.
The LM4915 contains advanced pop & click circuitry which
virtually eliminates noises which would otherwise occur during turn-on and turn-off transitions.
The LM4915 has an internally fixed gain of 6dB.
power supply.
DC
Typical Application
Key Specifications
n Improved PSRR at 217Hz and 1kHz 75dB (typ)
n Power Output at 5.0V & 1% THD into 32Ω 280mW (typ)
n Power Output at 3.0V & 1% THD into 32Ω 90mW (typ)
n Output Noise, A-weighted 20µV (typ)
Features
n Pseudo-differential amplification
n Internal gain-setting resistors
n Available in space-saving LLP package
n Ultra low current shutdown mode
n Can drive capacitive loads up to 500pF
n Improved pop & click circuitry virtually eliminates noises
during turn-on and turn-off transitions
n 2.2 - 5.5V operation
n No output coupling capacitors, snubber networks,
bootstrap capacitors or gain-setting resistors required
n Ultra low noise
Applications
n Mobile phones
n PDAs
n Portable electronics devices
200482B4
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer®is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200482 www.national.com
Connection Diagrams
LM4915
LQ Package
Top View
Order Number LM4915LQ
See NS Package Number LQB08A
8 Pin LQ Marking
200482E7
X - Date Code
TT - Die Traceability
G - Boomer
A5 - LM4915LQ
200482B5
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LM4915
Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Junction Temperature 150˚C
Thermal Resistance
θ
(LQ) 57˚C/W
JC
θ
(LQ) 140˚C/W
JA
Supply Voltage 6.0V
Storage Temperature −65˚C to +150˚C
Input Voltage -0.3V to V
DD
+ 0.3V
Power Dissipation (Note 3) Internally Limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Operating Ratings
Temperature Range
T
≤ TA≤ T
MIN
Supply Voltage (V
MAX
) 2.2V ≤ VCC≤ 5.5V
DD
−40˚C ≤ TA≤ +85˚C
Electrical Characteristics VDD=5V(Notes 1, 2, 8)
The following specifications apply for VDD= 5V, RL=16Ω unless otherwise specified. Limits apply to TA= 25˚C.
Symbol Parameter Conditions LM4915 Units
I
DD
I
SD
V
SDIH
V
SDIL
P
O
V
NO
Quiescent Power Supply Current VIN= 0V, IO= 0A 2 3.5 mA (max)
Shutdown Current V
Shutdown Voltage Input High 1.8 V
Shutdown Voltage Input Low 0.4 V
Output Power THD = 1% (max); f = 1kHz
Output Noise Voltage BW = 20Hz to 20kHz, A-weighted 20 µV
PSRR Power Supply Rejection Ratio V
V
OS
Output Offset Voltage VIN= 0V 2 20 mV (max)
SHUTDOWN
=16
R
L
=32
R
L
RIPPLE
Typ
(Note 6)
= GND 0.1 Note 9 µA(max)
400
280
= 200mV sine p-p 75 dB
Limit
(Note 7)
375
250
(Limits)
mW
Electrical Characteristics VDD= 3.0V (Notes 1, 2, 8)
The following specifications apply for VDD= 3.0V, RL=16Ω unless otherwise specified. Limits apply to TA= 25˚C.
Symbol Parameter Conditions LM4915 Units
Typ
(Note 6)
I
DD
I
SD
V
SDIH
V
SDIL
P
O
V
NO
PSRR Power Supply Rejection Ratio V
V
OS
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 T
allowable power dissipation is P
curves 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 specifications are guaranteed by design, test, or statistical analysis.
Quiescent Power Supply Current VIN= 0V, IO= 0A 1.5 2.5 mA (max)
Shutdown Current V
SHUTDOWN
= GND 0.1 Note 9 µA(max)
Shutdown Voltage Input High 1.8 V
Shutdown Voltage Input Low 0.4 V
Output Power THD = 1% (max); f = 1kHz
=16
R
L
=32
R
L
125
90
Output Noise Voltage BW = 20Hz to 20kHz, A-weighted 20 µV
= 200mV sine p-p 70 dB
RIPPLE
Output Offset Voltage VIN= 0V 2 20 mV (max)
, θJA, and the ambient temperature, TA. The maximum
DMAX
=(T
)/ θJAor the number given in Absolute Maximum Ratings, whichever is lower. For the LM4915, see power derating
JMAX-TA
JMAX
Limit
(Note 7)
100
80
(Limits)
mW (min)
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Electrical Characteristics VDD= 3.0V (Notes 1, 2, 8) (Continued)
Note 9: See ISDdistribution values shown in the ISDDistribution curve, VDD=5VandV=3V,shown in the Typical Performance Characteristics section.
LM4915
External Components Description (Figure 1)
Components Functional Description
1. C
2. C
Bypass pin capacitor that provides half-supply filtering. Refer to the section Proper Selection of External
B
Components for information concerning proper placement and selection of C
Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a
i
high-pass filter with the internal input resistance R
= 1/(2πRiCi). Refer to the section Proper Selection of External Components for an explanantion of
filter f
c
how to determine the value of C
.
i
. For the LM4915, Ri= 20kΩ, thus creating a high-pass
i
.
B
Typical Performance Characteristics
THD+N vs Frequency
= 5V, RL=16Ω
V
DD
THD+N vs Frequency
= 3V, RL=16Ω,PO= 100mW
V
DD
THD+N vs Frequency
VDD= 5V, RL=32Ω
200482C6 200482C7
THD+N vs Frequency
VDD= 3V, RL=32Ω,PO= 80mW
200482C4 200482C5
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