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LM4901
1.6 Watt Audio Power Amplifier with Selectable
Shutdown Logic Level
General Description
The LM4901 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 8
BTL
load and 1.6 watts of continuous avearge power to a 4
BTL
load with less than 1% distortion (THD+N) from a 5V
DC
power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4901 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 LM4901 features a low-power consumption shutdown
mode. To facilitate this, Shutdown may be enabled by either
logic high or low depending on mode selection. Driving the
shutdown mode pin either high or low enables the shutdown
pin to be driven in a likewise manner to enable shutdown.
The LM4901 contains advanced pop & click circuitry which
eliminates noise which would otherwise occur during turn-on
and turn-off transitions.
The LM4901 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
j
Improved PSRR at 217Hz & 1KHz
62dB
j
Power Output at 5.0V, 1% THD, 4
1.6W (typ)
j
Power Output at 5.0V, 1% THD, 8
1.07W (typ)
j
Power Output at 3.0V, 1% THD, 4
525mW (typ)
j
Power Output at 3.0V, 1% THD, 8
390mW (typ)
j
Shutdown Current
0.1A (typ)
Features
n
Available in space-saving packages: LLP, micro SMD,
and MSOP
n
Ultra low current shutdown mode
n
BTL output can drive capacitive loads
n
Improved pop & click circuitry eliminates noise during
turn-on and turn-off transitions
n
2.0 - 5.5V operation
n
No output coupling capacitors, snubber networks or
bootstrap capacitors required
n
Unity-gain stable
n
External gain configuration capability
n
User selectable shutdown High or Low logic Level
Applications
n
Mobile Phones
n
PDAs
n
Portable electronic devices
Typical Application
Boomer
is a registered trademark of National Semiconductor Corporation.
20019801
FIGURE 1. Typical Audio Amplifier Application Circuit
December 2002
LM4901
1.6
W
att
Audio
Power
Amplifier
with
Selectable
Shutdown
Logic
Level
2002 National Semiconductor Corporation
DS200198
www.national.com
Connection Diagrams
9 Bump micro SMD
Mini Small Outline (MSOP) Package
20019823
Top View
Order Number LM4901IBL, LM4901IBLX
See NS Package Number BLA09AAC
20019836
Top View
Order Number LM4901MM
See NS Package Number MUB10A
LLP Package
micro SMD Marking
200198B3
Top View
Order Number LM4901LD
See NS Package Number LDA10B
20019870
Top View
X - Date Code
T - Die Traceability
G - Boomer Family
Q - LM4901IBL
MSOP Marking
LLP Marking
20019871
Top View
G - Boomer Family
C1 - LM4901MM
200198B4
Top View
Z - Plant Code
XY - Date Code
TT - Die Traceability
Bottom Line - Part Number
LM4901
www.national.com
2
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (Note 11)
6.0V
Storage Temperature
-65C to +150C
Input Voltage
-0.3V to V
DD
+0.3V
Power Dissipation (Notes 3, 13)
Internally Limited
ESD Susceptibility (Note 4)
2000V
ESD Susceptibility (Note 5)
200V
Junction Temperature
150C
Thermal Resistance
JA
(micro SMD) (Note 12)
180C/W
JC
(MSOP)
56C/W
JA
(MSOP)
190C/W
JA
(LLP)
63C/W (Note 14)
JC
(LLP)
12C/W (Note 14)
Soldering Information
See AN-1112 "microSMD Wafers Level Chip Scale
Package."
See AN-1187 "Leadless
Leadframe Package (LLP)."
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
85C
Supply Voltage
2.0V
V
DD
5.5V
Electrical Characteristics V
DD
= 5V
(Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4901
Units
(Limits)
Typical
Limit
(Note 6)
(Notes 7, 9)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
o
= 0A, No Load
3
7
mA (max)
V
IN
= 0V, I
o
= 0A, 8
Load
4
10
mA (max)
I
SD
Shutdown Current
V
SD
= V
SD Mode
(Note 8)
0.1
2.0
A (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= V
DD
1.5
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= V
DD
1.3
V (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= GND
1.5
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= GND
1.3
V (max)
V
OS
Output Offset Voltage
7
50
mV (max)
R
OUT
Resistor Output to GND (Note 10)
8.5
9.7
k
(max)
7.0
k
(min)
P
o
Output Power (8
)
THD = 1% (max); f = 1 kHz
1.07
0.9
W (min)
(4
) (Notes 14, 15) THD = 1% (max); f = 1 kHz
1.6
W
T
WU
Wake-up time
100
mS (max)
THD+N
Total Harmonic Distortion+Noise
P
o
= 0.5 Wrms; f = 1kHz
0.2
%
PSRR
Power Supply Rejection Ratio
V
ripple
= 200mV sine p-p
Input terminated with 10
60 (f =
217Hz)
64 (f = 1kHz)
55
dB (min)
Electrical Characteristics V
DD
= 3V
(Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4901
Units
(Limits)
Typical
Limit
(Note 6)
(Notes 7, 9)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
o
= 0A, No Load
2
7
mA (max)
V
IN
= 0V, I
o
= 0A, 8
Load
3
9
mA (max)
I
SD
Shutdown Current
V
SD
= V
SD Mode
(Note 8)
0.1
2.0
A (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= V
DD
1.1
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= V
DD
0.9
V (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= GND
1.3
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= GND
1.0
V (max)
V
OS
Output Offset Voltage
7
50
mV (max)
LM4901
www.national.com
3
Electrical Characteristics V
DD
= 3V
(Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
A
=
25C. (Continued)
Symbol
Parameter
Conditions
LM4901
Units
(Limits)
Typical
Limit
(Note 6)
(Notes 7, 9)
R
OUT
Resistor Output to GND (Note 10)
8.5
9.7
k
(max)
7.0
k
(min)
P
o
Output Power (8
)
THD = 1% (max); f = 1 kHz
390
mW
(4
)
THD = 1% (max); f = 1 kHz
525
mW
T
WU
Wake-up time
75
mS (max)
THD+N
Total Harmonic Distortion+Noise
P
o
= 0.25 Wrms; f = 1kHz
0.1
%
PSRR
Power Supply Rejection Ratio
V
ripple
= 200mV sine p-p
Input terminated with 10
62 (f =
217Hz)
68 (f = 1kHz)
55
dB (min)
Electrical Characteristics V
DD
= 2.6V
(Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4901
Units
(Limits)
Typical
Limit
(Note 6)
(Notes 7, 9)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
o
= 0A, No Load
2.0
mA (max)
V
IN
= 0V, I
o
= 0A, 8
Load
3.0
mA (max)
I
SD
Shutdown Current
V
SD
= V
SD Mode
(Note 8)
0.1
A (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= V
DD
1.0
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= V
DD
0.9
V (max)
V
SDIH
Shutdown Voltage Input High
V
SD MODE
= GND
1.2
V (min)
V
SDIL
Shutdown Voltage Input Low
V
SD MODE
= GND
1.0
V (max)
V
OS
Output Offset Voltage
5
50
mV (max)
R
OUT
Resistor Output to GND (Note 10)
8.5
9.7
k
(max)
7.0
k
(min)
P
o
Output Power ( 8
)
THD = 1% (max); f = 1 kHz
275
mW
( 4
)
THD = 1% (max); f = 1 kHz
340
T
WU
Wake-up time
70
mS (max)
THD+N
Total Harmonic Distortion+Noise
P
o
= 0.15 Wrms; f = 1kHz
0.1
%
PSRR
Power Supply Rejection Ratio
V
ripple
= 200mV sine p-p
Input terminated with 10
51 (f =
217Hz)
51 (f = 1kHz)
dB (min)
Note 1: All voltages are measured with respect to the ground 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
JMAX
,
JA
, and the ambient temperature T
A
. The maximum
allowable power dissipation is P
DMAX
= (T
JMAX
T
A
)/
JA
or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4901, see power derating
curves for additional information.
Note 4: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 5: Machine Model, 220 pF240 pF discharged through all pins.
Note 6: Typicals are measured at 25C and represent the parametric norm.
Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 8: For micro SMD only, shutdown current is measured in a Normal Room Environment. Exposure to direct sunlight will increase I
SD
by a maximum of 2A.
Note 9: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
Note 10: R
ROUT
is measured from the output pin to ground. This value represents the parallel combination of the 10k
output resistors and the two 20k resistors.
Note 11: If the product is in Shutdown mode and V
DD
exceeds 6V (to a max of 8V V
DD
), then most of the excess current will flow through the ESD protection circuits.
If the source impedance limits the current to a max of 10mA, then the device will be protected. If the device is enabled when V
DD
is greater than 5.5V and less than
6.5V, no damage will occur, although operation life will be reduced. Operation above 6.5V with no current limit will result in permanent damage.
LM4901
www.national.com
4
Electrical Characteristics V
DD
= 2.6V
(Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
A
=
25C. (Continued)
Note 12: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The LM4901IBL demo board (views featured
in the Application Information section) has two inner layers, one for V
DD
and one for GND. The planes each measure 611mils x 661mils (15.52mm x 16.79mm)
and aid in spreading heat due to power dissipation within the IC.
Note 13: Maximum power dissipation in the device (P
DMAX
) occurs at an output power level significantly below full output power. P
DMAX
can be calculated using
Equation 1 shown in the Application Information section. It may also be obtained from the power dissipation graphs.
Note 14: The Exposed-DAP of the LDA10B package should be electrically connected to GND or an electrically isolated copper area. the LM4901LD demo board
(views featured in the Application Information section) has the Exposed-DAP connected to GND with a PCB area of 86.7mils x 585mils (2.02mm x 14.86mm) on
the copper top layer and 550mils x 710mils (13.97mm x 18.03mm) on the copper bottom layer.
Note 15: The thermal performance of the LLP package (LM4901LD) when used with the exposed-DAP connected to a thermal plane is sufficient for driving 4
loads. The LM4901LD demo board (views featured in the Application Information section) can drive 4
loads at the maximum power dissipation point (1.267W)
without thermal shutdown circuitry being activated. The other available packages (MSOP & micro SMD) do not have the thermal performance necessary for driving
4
loads with a 5V supply and are not recommended for this application.
External Components Description
(Figure 1)
Components
Functional Description
1.
R
i
Inverting input resistance which sets the closed-loop gain in conjunction with R
f
. This resistor also forms a
high pass filter with C
i
at f
C
= 1/(2
R
i
C
i
).
2.
C
i
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
highpass filter with R
i
at f
c
= 1/(2
R
i
C
i
). Refer to the section, Proper Selection of External Components,
for an explanation of how to determine the value of C
i
.
3.
R
f
Feedback resistance which sets the closed-loop gain in conjunction with R
i
.
4.
C
S
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.
5.
C
B
Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External
Components, for information concerning proper placement and selection of C
B
.
Typical Performance Characteristics
THD+N vs Frequency
at V
DD
= 5V, 8
R
L
, and PWR = 500mW
THD+N vs Frequency
at V
DD
= 3V, 8
R
L
, and PWR = 250mW
20019830
20019831
LM4901
www.national.com
5
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