4
Softstart
19
FB
20
FB_GND0
21
FB_GND1
1
FB_SEL
24
/SD_Boost
5
/SD_Amp
17
VGO-
16
IN+
15
IN-
14
VGO+
LM48511SQ
LS+
LS-
8
12
GND3
22
GND3
23
GND3
SW
SW
VD
D
2
3
1
8
PV1
10
V1
13
6.8
P
H
L1
10
P
F
CS1
GND3
1
P
F
CS2
GND3
1
P
F
CS3
GND2
VDD
D1
+
C2
100
P
F
GND3
GND2
GND1
+
C3
1
P
F
C4
1
P
F
2
1
Speaker
100 nF
CSoftstart
GND2
R2
9.31k
R1
4.87k
R4
2.5k
+
+
R3
25.5k
C1
280 pF
G
N
D
2
7
GND2
G
N
D
1
9
GND1
G
N
D
1
1
1
GND1
SS
-EN
6
1
2
3
SS_EN
1
2
3
VDD
GND2
R8
20k
R6
20k
R5
20k
R7
20k
CIN+
180 nF
CIN-
180 nF
GND3
GND2
GND1
GND
1
2
3
FB_SEL
1
2
3
VDD
GND2
1
2
3
SD_Boost
1
2
3
VDD
GND2
GND1 (Class D GND)
GND2 (AGND)
GND3 (Switch GND)
1
2
3
SD_Amp
1
2
3
VDD
GND2
1
2
4
Audio Input
1
2
4
GND2
3
3
1
2
VDD
VDD
GND2
GND2
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Application Circuit Schematic
6
Application Circuit Schematic
Figure 2. Typical LM48511 Audio Amplifier Application Circuit
7
Connections
Table 1. LM48511 Demonstration Board Connections
Designator
Function or Use
Supply Voltage (V
DD
)
The supply voltage operating range is from 3.0V to 5.5V, but the absolute maximum rating is 9V.
Connect a differential audio source to the two center pins of the Audio Input connector. For a single-
Audio Input
ended audio source, connect one of the center pins to the adjacent center pin (GND) and connect
the audio source to the remaining center pin.
Speaker (Audio Output)
Connect speaker load across the speaker connector.
Set SD_AMP Low to disable the Class D amplifier.
SD_Amp
Set SD_AMP High to enable the Class D amplifier.
Set SS_EN Low to enable Fixed frequency (FF) mode.
SS_EN Enable
Set SS_EN High to enable Spread Spectrum (SS) mode.
Set SD_Boost Low to disable the boost regulator.
SD_Boost
Set SD_Boost High to enable the boost regulator.
3
SNAA064C – November 2008 – Revised May 2013
AN-1922 LM48511 Evaluation Board
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