LM4947
Mono Class D and Stereo Audio Subsystem with OCL
Headphone Amplifier and National 3D
General Description
The LM4947 is an audio subsystem capable of efficiently
delivering 500mW (Classs D operation) of continuous aver-
age power into a mono 8
bridged-tied load (BTL) with 1%
THD+N, 36mW (Class AB operation) power channel of con-
tinuous average power into stereo 32
single-ended (SE)
loads with 1% THD+N, or an output capacitor-less (OCL)
configuration with identical specification as the SE configu-
ration, from a 3.3V power supply.
The LM4947 has six input channels: one pair for a two-
channel stereo signal, the second pair for a secondary two-
channel stereo input, and the third pair for a differential
single-channel mono input. Additionally, the two sets of ste-
reo inputs may be configured as a single stereo differential
input (differential left and differential right). The LM4947
features a 32-step digital volume control and eight distinct
output modes. The digital volume control, 3D enhancement,
and output modes are programmed through a two-wire I
2
C
compatible interface that allows flexibility in routing and mix-
ing audio channels.
The RF suppression circuitry in the LM4947 makes it well-
suited for GSM mobile phones and other portable applica-
tions in which strong RF signals generated by an antenna
(and long output traces) may couple audibly into the ampli-
fier.
The LM4947 is designed for cellular phones, PDAs, and
other portable handheld applications. It delivers high quality
output power from a surface-mount package and requires
only eight external components in the OCL mode (two addi-
tional components in SE mode).
Key Specifications
j
THD+N at 1kHz, 500mW
into 8
BTL (3.3V)
1.0% (typ)
j
THD+N at 1kHz, 36mW
into 32
SE (3.3V)
1.0% (typ)
j
Single Supply Operation (V
DD
)
2.7 to 5.5V
j
I
2
C Single Supply Operation
2.2 to 5.5V
Features
n
I
2
C Control Interface
n
I
2
C programmable National 3D Audio
n
I
2
C controlled 32 step digital volume control (-59.5dB to
+18dB)
n
Three independent volume channels (Left, Right, Mono)
n
Eight distinct output modes
n
Small, 25bump micro SMD packaging
n
"Click and Pop" suppression circuitry
n
Thermal shutdown protection
n
Low shutdown current (0.1uA, typ)
n
RF suppression
n
Differential mono and stereo inputs
n
Stereo input mux
Applications
n
Mobile Phones
n
PDAs
Boomer
is a registered trademark of National Semiconductor Corporation.
June 2006
LM4947
Mono
Class
D
and
Stereo
Audio
Subsystem
with
OCL
Headphone
Amplifier
and
National
3D
2006 National Semiconductor Corporation
DS201735
www.national.com
Connection Diagrams
25-Bump micro SMD
micro SMD Marking
20173501
Top View
20173507
Top View
XY - Date Code
TT - Die Traceability
G - Boomer Family
XX - H1
Pin Descriptions
Bump
Name
Description
A1
R
IN2
Right Input Channel 2 or Right Differential Input -
A2
L
IN1
Left Input Channel 1 or Left Differential Input +
A3
MONO_IN+
Loudspeaker Positive Input
A4
RHP
3D1
Right Headphone 3D Input 1
A5
RHP
3D2
Right Headphone 3D Input 2
B1
R
IN1
Right Input Channel 1 or Right Differential Input +
B2
L
IN2
Left Input Channel 2 or Left Differential Input -
B3
MONO_IN-
Loudspeaker Negative Input
B4
L
HP3D1
Left Headphone 3D Input 2
B5
L
HP3D2
Left Headphone 3D Input 1
C1
ADDR
Address Identification
C2
SDA
Data
C3
SCL
Clock
C4
C
BYPASS
Half-Supply Bypass Capacitor
C5
C
HP
Center Amplifier Output
D1
AV
DD
Analog Power Supply
D2
LSV
DD
Loudspeaker Power Supply
D3
I2CV
DD
I2C Interface Power Supply
D4
AV
DD
Analog Power Supply
D5
R
HP
Right Headphone Output
E1
LS-
Loudspeaker Output Negative
E2
GND
Ground
E3
LS+
Loudspeaker Output Positive
E4
GND
Ground
E5
L
HP
Left Headphone Output
LM4947
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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
6.0V
Storage Temperature
-65C to +150C
Input Voltage
-0.3 to V
DD
+0.3
ESD Susceptibility (Note 3)
2.0kV
ESD Machine model (Note 6)
200V
Junction Temperature (T
J
)
150C
Solder Information
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
Thermal Resistance
JA
(typ) - TLA25CBA
65C/W
Operating Ratings
Temperature Range
-40C to 85C
Supply Voltage (V
DD
)
2.7V
V
DD
5.5V
Supply Voltage (I
2
C)
2.2V
V
DD
5.5V
Supply Voltage (Loudspeaker V
DD
)
2.7V
V
DD
5.5V
Electrical Characteristics 3.3V
(Notes 2, 7)
The following specifications apply for V
DD
= 3.3V, T
A
= 25C, and all gains are set for 0dB unless otherwise specified.
Symbol
Parameter
Conditions
LM4947
Units
(Limits)
Typical
(Note 4)
Limits
(Note 5)
I
DD
Supply Current
Output Modes 2, 4, 6
V
IN
= 0V; No load,
OCL = 0 (Table 2)
4.5
mA (max)
Output Modes 1, 3, 5, 7
V
IN
= 0V; No load, BTL,
OCL = 0 (Table 2)
6.5
mA (max)
I
SD
Shutdown Current
Output Mode 0
0.1
1
A (max)
V
OS
Output Offset Voltage
V
IN
= 0V, Mode 7, Mono
2
15
mV (max)
V
IN
= 0V, Mode 7, Headphones
2
15
P
O
Output Power
MONO
OUT
; R
L
= 8
THD+N = 1%; f = 1kHz, BTL, Mode 1
500
400
mW (min)
R
OUT
and L
OUT
; R
L
= 32
THD+N = 1%; f = 1kHz, SE, Mode 4
37
33
mW (min)
THD+N
Total Harmonic Distortion Plus
Noise
MONO
OUT
f = 1kHz, P
OUT
= 250mW;
R
L
= 8
, BTL, Mode 1
0.04
%
R
OUT
and L
OUT
f = 1kHz, P
OUT
= 12mW;
R
L
= 32
, SE, Mode 4
0.07
%
N
OUT
Output Noise
A-weighted, 0dB
inputs terminated, output referred
Speaker; Mode 1
39
V
Speaker; Mode 3
39
V
Speaker; Mode 5
42
V
Speaker; Mode 7
38
V
Headphone; SE, Mode 2
15
V
Headphone; SE, Mode 4
15
V
Headphone; SE, Mode 6
17
V
Headphone; OCL, Mode 2
12
V
Headphone; OCL, Mode 4
15
V
Headphone; OCL, Mode 6
17
V
LM4947
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4
Electrical Characteristics 3.3V
(Notes 2, 7) (Continued)
The following specifications apply for V
DD
= 3.3V, T
A
= 25C, and all gains are set for 0dB unless otherwise specified.
Symbol
Parameter
Conditions
LM4947
Units
(Limits)
Typical
(Note 4)
Limits
(Note 5)
PSRR
Power Supply Rejection Ratio
Loudspeaker out
V
RIPPLE
= 200mV
PP
; f = 217Hz,
R
L
= 8
, C
B
= 2.2F, BTL
All audio inputs terminated to GND;
output referred
BTL, Output Mode 1
79
dB
BTL, Output Mode 3
78
dB
BTL, Output Mode 5
79
dB
BTL, Output Mode 7
80
dB
Power Supply Rejection Ratio
R
OUT
and L
OUT
V
RIPPLE
= 200mV
PP
; f = 217Hz,
R
L
= 32
, C
B
= 2.2F, BTL
All audio inputs terminated to GND;
output referred
SE, Output Mode 2
78
dB
SE, Output Mode 4
71
dB
SE, Output Mode 6
71
dB
OCL, Output Mode 2
83
dB
OCL, Output Mode 4
74
dB
OCL, Output Mode 6
74
dB
Class D Efficiency
Output Mode 1, 3, 5
86
%
CMRR
Common-Mode-Rejection Ratio
f = 217Hz, V
CM
= 1Vpp,
Mode 1, BTL, R
L
= 8
80
dB
f = 217Hz, V
CM
= 1Vpp,
Mode 2, R
L
= 32
59
XTALK
Crosstalk
Headphone, P
O
= 12mW,
f = 1kHz, OCL, Mode 4, R
L
= 32
58
dB
Headphone, P
O
= 12mW,
f = 1kHz, SE, Mode 4, R
L
= 32
73
T
WU
Wake-Up Time from Shutdown
C
B
= 2.2F, OCL, R
L
= 32
90
ms
C
B
= 2.2F, SE, R
L
= 32
115
Volume Control Step Size Error
0.2
dB
Digital Volume Range
Input referred maximum attenuation
-59.5
60.25
58.75
dB (min)
dB (max)
Input referred maximum gain
+18
17.25
18.75
dB (min)
dB (max)
Mute Attenuation
Output Mode 1, 3, 5
87
dB
MONO_IN Input Impedance
R
IN
and L
IN
Input Impedance
Maximum gain setting
12
8
14
k
(min)
k
(max)
Maximum attenuation setting
100
75
125
k
(min)
k
(max)
LM4947
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