LM4980
2 Cell Battery, 1mA, 42mW Per Channel High Fidelity
Stereo Headphone Audio Amplifier for MP3 players
General Description
The LM4980 is a stereo headphone audio amplifier, which
when connected to a 3.0V supply, delivers 42mW to a 16
load with less than 1% THD+N. With the LM4980 packaged
in the SD package, the customer benefits include low profile
and small size. This package minimizes PCB area and maxi-
mizes output power.
The LM4980 features circuitry that significantly reduces out-
put transients ("clicks" and "pops") while driving headphones
during device turn-on and turn-off without costly external
additional circuitry. The LM4980 also includes an externally
controlled low-power consumption active-low shutdown
mode, and thermal shutdown. Boomer audio power amplifi-
ers are designed specifically to use few external compo-
nents and provide high quality output power in a surface
mount package.
Key Specifications
j
Output power
(RL = 16
, V
DD
= 3.0V, THD+N = 1%)
42mW (typ)
j
Quiescent current (V
DD
= 3V)
1mA (typ)
j
Micropower shutdown current
0.1A (typ)
j
Supply voltage operating range
1.5V
<
V
DD
<
3.3V
j
PSRR
@
1kHz, V
DD
= 3.0V
90dB (typ)
j
PSRR
@
217Hz, V
DD
= 3.0V
100dB (typ)
Features
n
2-cell 1.5V to 3.3V battery operation
n
Unity-gain stable
n
"Click and pop" suppression circuitry for shutdown and
power on/off transient with headphone loads
n
Active low micro-power shutdown
n
Thermal shutdown protection circuitry
Applications
n
Portable two-cell audio products
n
Portable two-cell electronic devices
n
Portable MP3 player/recorders
Typical Application
Boomer
is a registered trademark of National Semiconductor Corporation.
20142901
FIGURE 1. Block Diagram
July 2005
LM4980
2
Cell
Battery
,
1mA,
42mW
Per
Channel
High
Fidelity
Stereo
Headphone
Audio
Amplifier
for
MP3
players
2005 National Semiconductor Corporation
DS201429
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
3.6V
Storage Temperature
-65C to +150C
Input Voltage
-0.3V to V
DD
+0.3V
Power Dissipation (Note 2)
Internally limited
ESD Susceptibility(Note 3)
2000V
ESD Susceptibility (Note 4)
200V
Junction Temperature
150C
Solder Information
Small Outline Package Vapor Phase (60sec)
215C
Infrared (15 sec)
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliablilty" for other methods of soldering
surface mount devices.
Thermal Resistance
JA
(typ) SDA10A
73C/W
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
+85C
Supply Voltage
1.5V
V
DD
3.3V
Electrical Characteristics V
DD
= 3.0V
(Notes 1, 5)
The following specifications apply for the circuit shown in Figure 2, unless otherwise specified. A
V
= 0dB, R
L
= 32
.
Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4980
Units
(Limits)
Typical
Limit
(Note 6)
(Note 7)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
O
= 0A, R
L
=
(Note 8)
1.0
1.5
mA (max)
I
SD
Shutdown Current
V
SHDN
= GND
0.1
1
A (max)
V
OS
Output Offset Voltage
1
5
mV
P
O
Output Power (Note 9)
R
L
= 16
,
THD+N = 1%, f = 1kHz, per channel
42
35
mW (min)
R
L
= 32
,
THD+N = 1%, f = 1kHz, per channel
28
mW (min)
V
NO
Output Voltage Noise
20Hz to 20kHz, A-weighted, Fig. 2
10
V
RMS
THD+N
Total Harmonic Distortion + Noise
R
L
= 32
, P
OUT
= 10mW, f = 1kHz
0.02
%
Crosstalk
Freq = 1kHz, P
OUT
= 28mW, R
L
= 32
77
dB
PSRR
Power Supply Rejection Ratio
V
RIPPLE
= 200mV
P-P
sine wave
f
RIPPLE
= 1kHz, C
MIDCAP
= 4.7F,
V
MID
Voltage is Ripple-Free
90
dB
V
RIPPLE
= 200mV
P-P
sine wave
f
RIPPLE
= 217Hz, C
MIDCAP
= 4.7F,
V
MID
Voltage is Ripple-Free
100
dB
CMRR
Common-Mode Rejection Ratio
Input coupling capacitors with 5%
tolerance, V
IN
= V
MID
,
f
RIPPLE
= 1kHz
47
dB
T
WAKE-UP
Wake-up Time
C
MIDCAP
= 4.7F, Fig 2.
250
ms
V
IH
Control Logic High
1.5V
V
DD
3.3V
1.4V
V (min)
V
IL
Control Logic Low
1.5V
V
DD
3.3V
0.4V
V (max)
Electrical Characteristics V
DD
= 1.8V
(Notes 1, 5)
The following specifications apply for the circuit shown in Figure 2, unless otherwise specified. A
V
= 0dB, R
L
= 32
.
Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4980
Units
(Limits)
Typical
Limit
(Note 6)
(Note 7)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
O
= 0A, R
L
=
(Note 8)
0.9
mA
I
SD
Shutdown Current
V
SHDN
= GND
0.1
A
V
OS
Output Offset Voltage
1
mV
LM4980
www.national.com
4
Electrical Characteristics V
DD
= 1.8V
(Notes 1, 5) (Continued)
The following specifications apply for the circuit shown in Figure 2, unless otherwise specified. A
V
= 0dB, R
L
= 32
.
Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4980
Units
(Limits)
Typical
Limit
(Note 6)
(Note 7)
P
O
Output Power (Note 9)
R
L
= 16
,
THD+N = 1%, f = 1kHz, per channel
11
mW (min)
R
L
= 32
,
THD+N = 1%, f = 1kHz, per channel
9
mW (min)
V
NO
Output Voltage Noise
20Hz to 20kHz, A-weighted, Fig. 2
9
V
RMS
THD+N
Total Harmonic Distortion + Noise
R
L
= 32
, P
OUT
= 10mW, f = 1kHz
0.03
%
Crosstalk
Freq = 1kHz, P
OUT
= 9mW, R
L
= 32
79
dB
PSRR
Power Supply Rejection Ratio
V
RIPPLE
= 200mV
P-P
sine wave
f
RIPPLE
= 1kHz, C
MIDCAP
= 4.7F,
V
MID
Voltage is Ripple-Free
78
dB
V
RIPPLE
= 200mV
P-P
sine wave
f
RIPPLE
= 217Hz, C
MIDCAP
= 4.7F,
V
MID
Voltage is Ripple-Free
85
dB
CMRR
Common-Mode Rejection Ratio
Input coupling capacitors with 5%
tolerance, V
IN
= V
MID
,
f
RIPPLE
= 1kHz
47
dB
T
WAKE-UP
Wake-up Time
C
MIDCAP
= 4.7F, Fig 2.
320
ms
V
IH
Control Logic High
1.5V
V
DD
3.3V
1.4V
V (min)
V
IL
Control Logic Low
1.5V
V
DD
3.3V
0.4V
V (max)
Note 1: 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 2: The maximum power dissipation is dictated by T
JMAX
,
JA
, and the ambient temperature T
A
must be derated at elevated temperatures. The maximum
allowable power dissipation is P
DMAX
= (T
JMAX
- T
A
) /
JA
. For the LM4980, T
JMAX
= 150C. For the
JA
s, please see the Application Information section or the
Absolute Maximum Ratings section.
Note 3: Human body model, 100pF discharged through a 1.5k
resistor.
Note 4: Machine model, 200pF 220pF discharged through all pins.
Note 5: All voltages are measured with respect to the ground (GND) pins unless otherwise specified.
Note 6: Typicals are measured at 25C and represent the parametric norm.
Note 7: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
Note 8: The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.
Note 9: Output power is measured at the device terminals.
LM4980
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