LM48821
LM48821 Direct Coupled, Ultra Low Noise, 52mW Differential Input Stereo
HeadphoneAmplifier with I2C Volume Control
Literature Number: SNAS354
June 2007
LM48821
Direct Coupled, Ultra Low Noise, 52mW Differential Input
Stereo Headphone Amplifier with I2C Volume Control
General Description
With its directly-coupled output technology, the LM48821 is a
variable gain audio power amplifier capable of delivering
52mWRMS per channel into a 16Ω single-ended load with less
than 1% THD+N from a 3V power supply. The I2C volume
control has a range of –76dB to 18dB.
The LM48821's Tru-GND technology utilizes advanced
charge pump technology to generate the LM48821’s negative
supply voltage. This eliminates the need for output-coupling
capacitors typically used with single-ended loads.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM48821 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 LM48821 incorporates selectable low-power consump-
tion shutdown and channel select modes.
The LM48821 contains advanced output transient suppres-
sion circuitry that eliminates noises which would otherwise
occur during turn-on and turn-off transitions.
Key Specifications
■ Improved PSRR at 217Hz 82dB (typ)
■ Stereo Output Power at VDD = 3V,
RL = 16Ω, THD+N = 1% 52mW (typ)
■ Mono Output Power at VDD = 3V,
RL = 16Ω, THD+N = 1% 93mW (typ)
■ Shutdown current 0.1μA (typ)
Features
■Ground referenced outputs
■Differential Inputs
■I2C Volume and mode controls
■Available in space-saving micro SMD package
■Ultra low current shutdown mode
■Advanced output transient suppression circuitry
eliminates noises during turn-on and turn-off transitions
■2.0V to 4.0V operation (PVDD and SVDD)
■1.8 to 4.0V operation (I2CVDD)
■No output coupling capacitors, snubber networks,
bootstrap capacitors, or gain-setting resistors required
Applications
■Notebook PCs
■Desktop PCs
■Mobile Phones
■PDAs
■Portable Electronic Devices
■MP3 Players
Boomer® is a registered trademark of National Semiconductor Corporation.
Tru-GND is a trademark of National Semiconductor Corporation.
© 2007 National Semiconductor Corporation 201842 www.national.com
LM48821 Direct Coupled, Ultra Low Noise, 52mW Differential Input Stereo Headphone Amplifier
with I2C Volume Control
Typical Application
20184211
FIGURE 1. Typical Audio Amplifier Application Circuit
www.national.com 2
LM48821
Connection Diagrams
micro SMD Package
201842d7
Top View
Order Number TLA1611A
See NS Package Number TLA1611A
micro SMD Marking
201842d8
Top View
XY - Date Code
TT - Lot Traceability
GG3 – LM48821
Pin Descriptions
Pin Designator Pin Name Pin Function
A1 SVDD Signal power supply input
A2 SGND Signal ground
A3 IN A+ Left non-inverting input
A4 IN A- Left inverting input
B1 VOA Left output
B2 VOB Right output
B3 IN B+ Right non-inverting input
B4 IN B- Right inverting input
C1 VSS DC to DC converter output
C2 SCL I2C serial clock input
C3 SDA I2C serial data input
C4 I2CVDD I2C supply voltage input
D1 CCP- DC to DC converter flying capacitor inverting input
D2 PGND Power ground
D3 CCP+ DC to DC converter flying capacitor non-inverting input
D4 PVDD DC to DC converter power supply input
3 www.national.com
LM48821
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage 4.5V
Storage Temperature −65°C to +150°C
Input Voltage −0.3V to VDD +0.3V
Power Dissipation (Note 3) Internally Limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Junction Temperature 150°C
Thermal Resistance
θJA (typ) - (TLA1611A) (Note 3) 105°C/W
Operating Ratings
Temperature Range
TMIN ≤ TA ≤ TMAX −40°C ≤ TA ≤ +85°C
Supply Voltage
PVDD and SVDD 2.0V ≤ VDD ≤ 4.0V
I2CVDD 1.8V ≤ I2CVDD ≤ 4.0V
Audio Amplifier Electrical Characteristics VDD = 3V (Notes 1, 2)
The following specifications apply for VDD = 3V, RL = 16Ω, AV = 0dB, unless otherwise specified. Limits apply for TA = 25°C.
Symbol Parameter Conditions
LM48821 Units
(Limits)
Typical
(Note 6)
Limits
(Notes 7, 8)
IDD
Quiescent Power Supply
Current
VIN = 0V, inputs terminated,
both channels enabled 3.0 4.5 mA (max)
VIN = 0V, inputs terminated,
one channel enabled 2.0 3.0 mA
ISD Shutdown Current Right and Left Enable bits set to 0 0.1 1.2 µA (max)
VOS Output Offset Voltage RL = 32Ω 0.5 2.5 mV (max)
AVVolume Control Range [B0:B4] = 00000 –76 dB
[B0:B4] = 11111 +18 dB
ΔAVChannel-to-Channel Gain Match ±0.015 dB
AV-MUTE Mute Gain –76 dB
RIN Input Resistance Gain = 18dB 9 5
15
kΩ (min)
kΩ (max)
Gain = –76dB 81 kΩ
POUT Output Power
THD+N = 1% (max); fIN = 1kHz,
RL = 16Ω, per channel 52 43 mW (min)
THD+N = 1% (max); fIN = 1kHz,
RL = 32Ω, per channel 53 45 mW (min)
THD+N = 1% (max); fIN = 1kHz,
RL = 16Ω, single channel driven 93 80 mW (min)
THD+N = 1% (max); fIN = 1kHz,
RL = 32Ω, single channel driven 79 mW
THD+N Total Harmonic Distortion +
Noise
POUT = 50mW, f = 1kHz
RL = 16Ω, single channel 0.022 %
POUT = 50mW, f = 1kHz
RL = 32Ω, single channel 0.011 %
PSRR Power Supply Rejection Ratio
VRIPPLE = 200mVP-P, input referred
f = 217Hz
f = 1kHz
f = 20kHz
82
80
55
65 dB (min)
dB
dB
CMRR Common Mode Rejection Ratio VRIPPLE = 200mVp-p, Input referred
f = 2kHz 65 dB
SNR Signal-to-Noise-Ratio RL = 32Ω, POUT = 20mW,
f = 1kHz, BW = 20Hz to 22kHz 100 dB
TWU Charge Pump Wake-Up Time 400 μs
www.national.com 4
LM48821
Symbol Parameter Conditions
LM48821 Units
(Limits)
Typical
(Note 6)
Limits
(Notes 7, 8)
XTALK Crosstalk RL = 16Ω, POUT = 1.6mW,
f = 1kHz, A-weighted filter 82 dB
ZOUT Output Impedance Right and Left Enable bits set to 0 41 kΩ
Control Interface Electrical Characteristics (Notes 1, 2)
The following specifications apply for 1.8V ≤ I2CVDD ≤ 4.0V, unless otherwise specified. Limits apply for TA = 25°C. See Figure 2.
Symbol Parameter Conditions
LM48821 Units
(Limits)
Typical
(Note 6)
Limits (Notes 7,
8)
t1SCL period 2.5 μs (min)
t2SDA Setup Time 100 ns (min)
t3SDA Stable Time 0 ns (min)
t4Start Condition Time 100 ns (min)
t5Stop Condition Time 100 ns (min)
VIH Logic High Input Threshold 0.7 x I2CVDD V (min)
VIL Logic Low Input Threshold 0.3 x I2CVDD V (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 LM48821, 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.
5 www.national.com
LM48821
Typical Performance Characteristics
THD+N vs Frequency
VDD = 2V, PO = 6mW,
RL = 16Ω, Stereo
20184232
THD+N vs Frequency
VDD = 2V, PO = 10mW,
RL = 32Ω, Stereo
20184233
THD+N vs Frequency
VDD = 2V, PO = 16mW,
RL = 16Ω, Mono Left
20184234
THD+N vs Frequency
VDD = 2V, PO = 16mW,
RL = 16Ω, Mono Right
20184235
THD+N vs Frequency
VDD = 2V, PO = 18mW,
RL = 32Ω, Mono Left
20184236
THD+N vs Frequency
VDD = 2V, PO = 18mW,
RL = 32Ω, Mono Right
20184237
www.national.com 6
LM48821
THD+N vs Frequency
VDD = 3V, PO = 35mW,
RL = 16Ω, Stereo
20184238
THD+N vs Frequency
VDD = 4V, PO = 50mW,
RL = 16Ω, Stereo
20184239
THD+N vs Frequency
VDD = 3V, PO = 70mW,
RL = 16Ω, Mono Left
201842b9
THD+N vs Frequency
VDD = 3V, PO = 70mW,
RL = 16Ω, Mono Right
201842c0
THD+N vs Frequency
VDD = 4V, PO = 160mW,
RL = 16Ω, Mono Left
201842c1
THD+N vs Frequency
VDD = 4V, PO = 160mW,
RL = 16Ω, Mono Right
201842c2
7 www.national.com
LM48821
THD+N vs Frequency
VDD = 3V, PO = 40mW,
RL = 32Ω, Stereo
201842c3
THD+N vs Frequency
VDD = 3V, PO = 60mW,
RL = 32Ω, Mono Left
201842c4
THD+N vs Frequency
VDD = 3V, PO = 60mW,
RL = 32Ω, Mono Right
201842c5
THD+N vs Frequency
VDD = 4V, PO = 90mW,
RL = 32Ω, Stereo
201842c6
THD+N vs Frequency
VDD = 4V, PO = 120mW,
RL = 32Ω, Mono Left
201842c7
THD+N vs Frequency
VDD = 4V, PO = 120mW,
RL = 32Ω, Mono Right
201842c8
www.national.com 8
LM48821
THD+N vs Output Power
VDD = 2V, RL = 16Ω,
f = 1kHz, Mono Left
20184240
THD+N vs Output Power
VDD = 2V, RL = 16Ω,
f = 1kHz, Mono Right
20184241
THD+N vs Output Power
VDD = 2V, RL = 16Ω,
f = 1kHz, Stereo
20184242
THD+N vs Output Power
VDD = 3V, RL = 16Ω,
f = 1kHz, Mono Left
20184243
THD+N vs Output Power
VDD = 3V, RL = 16Ω,
f = 1kHz, Mono Right
20184244
THD+N vs Output Power
VDD = 3V, RL = 16Ω,
f = 1kHz, Stereo
20184245
9 www.national.com
LM48821
THD+N vs Output Power
VDD = 4V, RL = 16Ω,
f = 1kHz, Mono Left
20184246
THD+N vs Output Power
VDD = 4V, RL = 16Ω,
f = 1kHz, Mono Right
20184247
THD+N vs Output Power
VDD = 4V, RL = 16Ω,
f = 1kHz, Stereo
20184299
THD+N vs Output Power
VDD = 2V, RL = 32Ω,
f = 1kHz, Mono Left
20184248
THD+N vs Output Power
VDD = 2V, RL = 32Ω,
f = 1kHz, Mono Right
20184249
THD+N vs Output Power
VDD = 2V, RL = 32Ω,
f = 1kHz, Stereo
20184250
www.national.com 10
LM48821
THD+N vs Output Power
VDD = 3V, RL = 32Ω,
f = 1kHz, Mono Left
20184251
THD+N vs Output Power
VDD = 3V, RL = 32Ω,
f = 1kHz, Mono Right
20184252
THD+N vs Output Power
VDD = 3V, RL = 32Ω,
f = 1kHz, Stereo
20184253
THD+N vs Output Power
VDD = 4V, RL = 32Ω,
f = 1kHz, Mono Left
20184254
THD+N vs Output Power
VDD = 4V, RL = 32Ω,
f = 1kHz, Mono Right
20184255
THD+N vs Output Power
VDD = 4V, RL = 32Ω,
f = 1kHz, Stereo
20184256
11 www.national.com
LM48821
CMRR vs Frequency
VDD = 3V, RL = 16Ω
201842d9
PSRR vs Frequency
VDD = 2V, RL = 16Ω
20184226
PSRR vs Frequency
VDD = 2V, RL = 32Ω
20184227
PSRR vs Frequency
VDD = 3V, RL = 16Ω
20184228
PSRR vs Frequency
VDD = 3V, RL = 32Ω
20184229
PSRR vs Frequency
VDD = 4V, RL = 16Ω
20184230
www.national.com 12
LM48821
PSRR vs Frequency
VDD = 4V, RL = 32Ω
20184231
Output Power vs Voltage Supply
RL = 16Ω, Mono
20184212
Output Power vs Voltage Supply
RL = 32Ω, Mono
20184213
Output Power vs Voltage Supply
RL = 16Ω, Stereo
20184216
Output Power vs Voltage Supply
RL = 32Ω, Stereo
20184217
Output Power vs Power Dissipation
VDD = 2V, 3V, 4V, RL = 16Ω, Mono
20184214
13 www.national.com
LM48821
Output Power vs Power Dissipation
VDD = 2V, 3V, 4V, RL = 32Ω, Mono
20184215
Output Power vs Power Dissipation
VDD = 2V, 3V, 4V, RL = 16Ω, Stereo
20184218
Output Power vs Power Dissipation
VDD = 2V, 3V, 4V, RL = 32Ω, Stereo
20184219
Supply Current vs Supply Voltage
Mono
20184209
Supply Current vs Supply Voltage
Stereo
20184210
www.national.com 14
LM48821
Application Information
20184267
FIGURE 2. I2C Timing Diagram
20184268
FIGURE 3. I2C Bus Format
TABLE 1. Chip Address
D7 D6 D5 D4 D3 D2 D1 D0
Chip Address 1 1 1 0 1 1 0 0
TABLE 2. Control Registers
D7 D6 D5 D4 D3 D2 D1 D0
Volume Control VD4 VD3 VD2 VD1 VD0 MUTE LF
ENABLE
RT
ENABLE
15 www.national.com
LM48821
I2C VOLUME CONTROL
The LM48821 can be configured in 32 different gain steps by forcing I2C volume control bits to a desired gain according to the
table below:
TABLE 3. Volume Control
VD4 VD3 VD2 VD1 VD0 Gain (dB)
0 0 0 0 0 –76
0 0 0 0 1 –62
0 0 0 1 0 –52
0 0 0 1 1 –44
0 0 1 0 0 –38
0 0 1 0 1 –34
0 0 1 1 0 –30
0 0 1 1 1 –27
0 1 0 0 0 –24
0 1 0 0 1 –21
0 1 0 1 0 –18
0 1 0 1 1 –16
0 1 1 0 0 –14
0 1 1 0 1 –12
0 1 1 1 0 –10
0 1 1 1 1 –8
1 0 0 0 0 –6
1 0 0 0 1 –4
1 0 0 1 0 –2
1 0 0 1 1 0
1 0 1 0 0 2
1 0 1 0 1 4
1 0 1 1 0 6
1 0 1 1 1 8
1 1 0 0 0 10
1 1 0 0 1 12
1 1 0 1 0 13
1 1 0 1 1 14
1 1 1 0 0 15
1 1 1 0 1 16
1 1 1 1 0 17
1 1 1 1 1 18
www.national.com 16
LM48821
I2C COMPATIBLE INTERFACE
The LM48821 uses a serial data bus that conforms to the I2C
protocol. Controlling the chip’s functions is accomplished with
two wires: serial clock (SCL) and serial data (SDA). The clock
line is uni-directional. The data line is bi-directional (open-
collector). The maximum clock frequency specified by the
I2C standard is 400kHz. In this discussion, the master is the
controlling microcontroller and the slave is the LM48821.
The bus format for the I2C interface is shown in Figure 3. The
bus format diagram is broken up into six major sections: The
Start Signal, the I2C Address, an Acknowledge bit, the I2C
data, second Acknowledge bit, and the Stop Signal.
The start signal is generated by lowering the data signal while
the clock signal is high. The start signal will alert all devices
attached to the I2C bus to check the incoming address against
their own address.
The 8-bit chip address is sent next, most significant bit first.
The data is latched in on the rising edge of the clock. Each
address bit must be stable while the clock level is high.
After the last bit of the address bit is sent, the master releases
the data line high (through a pull-up resistor). Then the master
sends an acknowledge clock pulse. If the LM48821 has re-
ceived the address correctly, then it holds the data line low
during the clock pulse. If the data line is not held low during
the acknowledge clock pulse, then the master should abort
the rest of the data transfer to the LM48821. The 8 bits of data
are sent next, most significant bit first. Each data bit should
be valid while the clock level is stable high.
After the data byte is sent, the master must check for another
acknowledge to see if the LM48821 received the data.
If the master has more data bytes to send to the LM48821,
then the master can repeat the previous two steps until all
data bytes have been sent.
The stop signal ends the transfer. To signal stop , the data
signal goes high while the clock signal is high. The data line
should be held high when not in use.
The LM48821's I2C address is shown in Table 1. The I2C data
register and its control bit names are shown in Table 2. The
data values for the volume control are shown in Table 3.
I2C INTERFACE POWER SUPPLY PIN (I2CVDD)
The LM48821’s I2C interface is powered up through the
I2CVDD pin. The LM48821’s I2C interface operates at a volt-
age level set by the I2CVDD pin. This voltage can be indepen-
dent from the main power supply pin (VDD). This is ideal
whenever logic levels for the I2C interface are dictated by a
microcontroller or microprocessor that is operating at a lower
supply voltage than the main battery of a portable system.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is crit-
ical for low noise performance and high power supply rejec-
tion. Applications that employ a 3.3V voltage regulator
typically use a 10μF in parallel with a 0.1μF filter capacitors
to stabilize the regulator’s output, reduce noise on the regu-
lated supply lines, and improve the regulator’s transient re-
sponse. However, their presence does not eliminate the need
for a local 1.0μF tantalum bypass capacitance connected be-
tween the LM48821’s supply pins and ground. Keep the
length of leads and traces that connect capacitors between
the LM48821’s power supply pins and ground as short as
possible.
ELIMINATING THE OUTPUT COUPLING CAPACITOR
The LM48821 features a low noise inverting charge pump that
generates an internal negative supply voltage. This allows the
LM48821 to reference its amplifier outputs to ground instead
of a half-supply voltage, like traditional capacitivel-coupled
headphone amplifiers. Because there is no DC bias voltage
associated with either stereo output, the large DC blocking
capacitors (typically 220μF) are not necessary. The coupling
capacitors are replaced by two, small ceramic charge pump
capacitors, saving board space and cost.
Eliminating the output coupling capacitors also improves low
frequency response. In traditional headphone amplifiers, the
headphone impedance and the output capacitor form a high
pass filter that not only blocks the DC component of the out-
put, but also attenuates low frequencies, impacting the bass
response. Because the LM48821 does not require the output
coupling capacitors, the low frequency response of the device
is not degraded.
In addition to eliminating the output coupling capacitors, the
ground referenced output nearly doubles the output voltage
swing and available dynamic range of the LM48821 when
compared to a traditional capacitively-coupled output head-
phone amplifier operating from the same supply voltage.
OUTPUT TRANSIENT ELIMINATED
The LM48821 contains advanced circuitry that virtually elim-
inates output transients (’clicks' and 'pops’). This circuitry
attenuates output transients when the supply voltage is first
applied or when the part resumes operation after using the
shutdown mode.
POWER DISSIPATION
Power dissipation is a major concern when using any power
amplifier and must be thoroughly understood to ensure a suc-
cessful design. Equation 1 states the maximum power dissi-
pation point for a single-ended amplifier operating at a given
supply voltage and driving a specified output load.
PDMAX = (2VDD)2 / (2π2RL) (1)
Since the LM48821 has two power amplifiers in one package,
the maximum internal power dissipation point is twice that of
the number which results from Equation 1. Even with large
internal power dissipation, the LM48821 does not require heat
sinking over a large range of ambient temperatures. The max-
imum power dissipation point obtained must not be greater
than the power dissipation that results from Equation 2:
PDMAX = (TJMAX - TA) / (θJA) (2)
For the micro SMD package, θJA = 105°C/W. TJMAX = 150°C
for the LM48821. Depending on the ambient temperature,
TA, of the system surroundings, Equation 2 can be used to
find the maximum internal power dissipation supported by the
IC packaging. If the result of Equation 1 is greater than that
of Equation 2, then either the supply voltage must be de-
creased, the load impedance increased or TA reduced. Power
dissipation is a function of output power and thus, if typical
operation is not around the maximum power dissipation point,
the ambient temperature may be increased accordingly.
17 www.national.com
LM48821
SELECTING EXTERNAL COMPONENTS
Optimizing the LM48821’s performance requires properly se-
lecting external components. Though the LM48821 operates
well when using external components with wide tolerances,
best performance is achieved by optimizing component val-
ues.
Charge Pump Capacitor Selection
Use low ESR (equivalent series resistance) (<100mΩ) ce-
ramic capacitors with an X7R dielectric for best performance.
Low ESR capacitors keep the charge pump output
impedance to a minimum, extending the headroom on the
negative supply. Higher ESR capacitors result in reduced
output power from the audio amplifiers.
Charge pump load regulation and output impedance are af-
fected by the value of the flying capacitor (connected between
the CCP- and CCP+ pins). A larger valued C1 (up to 4.7μF) im-
proves load regulation and minimizes charge pump output
resistance. Beyond 4.7μF, the switchon-resistance domi-
nates the output impedance.
The output ripple is affected by the value and ESR of the out-
put capacitor (connected between the VSS and PGND pins).
Larger capacitors reduce output ripple on the negative power
supply. Lower ESR capacitors minimize the output ripple and
reduce the output impedance of the charge pump.
The LM48821 charge pump design is optimized for 4.7μF, low
ESR, ceramic, flying, and output capacitors.
Power Supply Bypass Capacitor
For good THD+N and low noise performance and to ensure
correct power-on behavior at the maximum allowed power
supply voltage, a local 4.7μF power supply bypass capacitor
should be connected as physically closed as possible to the
PVDD pin.
Input Capacitor Value Selection
Amplifying the lowest audio frequencies requires high value
input coupling capacitors (the 0.47μF capacitors in Figure 1).
A high value capacitor can be expensive and may compro-
mise space efficiency in portable designs. In many cases,
however, the speakers used in portable systems, whether in-
ternal or external, have little ability to reproduce signals below
150Hz. Applications using speakers with this limited frequen-
cy response reap little improvement by using high value input
and output capacitors.
Besides affecting system cost and size, the input coupling
capacitor value has an effect on the LM48821’s click and pop
performance. The magnitude of the pop is directly propor-
tional to the input capacitor’s size. Thus, pops can be mini-
mized by selecting an input capacitor value that is no higher
than necessary to meet the desired -3dB frequency.
The LM48821's nominal input resistance at full volume is
10kΩ and a minimum of 5kΩ. This input resistance and the
input coupling capacitor value produce a -3dB high pass filter
cutoff frequency that is found using Equation 3.
f-3dB = 1/2πRiCi(3)
www.national.com 18
LM48821
Revision History
Rev Date Description
1.0 06/06/07 Initial release.
19 www.national.com
LM48821
Physical Dimensions inches (millimeters) unless otherwise noted
16-Bump micro SMD
Order Number LM48821TL
NS Package Number TLA1611A
X1 = 1.970± 0.03 X2 = 1.970 ± 0.03 X3 = 0.6 ± 0.075
www.national.com 20
LM48821
Notes
21 www.national.com
LM48821
Notes
LM48821 Direct Coupled, Ultra Low Noise, 52mW Differential Input Stereo Headphone Amplifier
with I2C Volume Control
THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION
(“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY
OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO
SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS,
IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS
DOCUMENT.
TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT
NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL
PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR
APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND
APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE
NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS.
EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO
LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE
AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR
PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY
RIGHT.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and
whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected
to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform
can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness.
National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other
brand or product names may be trademarks or registered trademarks of their respective holders.
Copyright© 2007 National Semiconductor Corporation
For the most current product information visit us at www.national.com
National Semiconductor
Americas Customer
Support Center
Email:
new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor Europe
Customer Support Center
Fax: +49 (0) 180-530-85-86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +49 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor Asia
Pacific Customer Support Center
Email: ap.support@nsc.com
National Semiconductor Japan
Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
