AudioMAX
T
H E
TM
LX1720
D
A T A
S
WITCHING
C
LASS
-D, S
TEREO
P
OWER
A
MPLIFIER
C
ONTROLLER
IC
I
N F I N I T E
P
O W E R
O F
I
N N O VA T I O N
P
R O D U C T I O N
S
H E E T
DESCRIPTION
The
LX1720
is a highly-integrated,
Switching Class-D Stereo Power Am-
plifier Controller IC
with power and
size features that make it ideal for multi-
media computer applications, as well as
other applications where high fidelity
sound is required.
With input voltage ranging from 7V-
15V, the LX1720 is designed to operate
over the full 20Hz to 20kHz audio range.
Signal distortion measurements using
industry standard 1kHz signal yields THD
+ noise levels < 1% (10 watts output).
Its high efficiency (>92%) eliminates the
need for heat sinks — even while deliv-
ering more than 10W
RMS
across 8 ohms
per channel (20W
RMS
stereo) with 0.1 ohm
SO-8 power FETs.
The LX1720's output power is limited
only by external FETs and available sup-
ply voltage.
While offering breakthrough perfor-
mance capabilities for notebooks, the
LX1720 is equally attractive for multime-
dia systems or to drive full-size home
theatre speakers.
K E Y F E AT U R E S
s
Integrated Switching (Class-D) Stereo
Power Amplifier Controller IC
s
Delivers >10W
RMS
Across 8Ω /Channel
(20W
RMS
stereo)
s
Output Power Limited Only By External
FETs And Available Supply Voltage
s
Will Drive A Wide Range Of Speakers
s
High Efficiency (>92%)
s
Due To High Efficiency, Power FETs Do Not
Require Heatsinking
s
Audio Bandwidth Of 20Hz to 20kHz
s
Wide Input Voltage Range Of 7V-15V
s
Low Output Signal Distortion <1%
s
High Operating Frequency (350kHz) Helps
To Reduce Output Filter Size
s
Compact Design Minimizes EMI / RFI
IMPORTANT:
For the most current data, consult LinFinity's web site:
http://www.linfinity.com.
PRODUCT HIGHLIGHT
APPLICATIONS / BENEFITS
E
F F I C I E N C Y
C
O M PA R I S O N
100
OF THE
C
LASS
-D A
MPLFIER
Notebook Computers:
s
Replaces existing internal low power linear
amplifier with a high efficiency Class-D
amplifier
s
Enables the use of virtually any external
speaker without amplification
s
Precious battery life is extended
s
Fully protected power topology can
withstand shorts or external speaker
failures without damage, overheating or
posing fire hazard
- Average Power Out for 20sec. approx. 512mW
- Across 8.6 Ohm Load
80
Linfinity's LX1720
Class-D Amplifier
Efficiency (%)
60
Desktop Computers:
s
Output power capability of up to 20W
RMS
per channel in an area less than 3"x3",
without using expensive heatsinks
s
Greatly reduced power supply
requirements when compared to a linear
solution of same power capabilities
s
Any speakers can be used including
conventional home stereo speakers
s
Very light weight circuitry will not add to
the overall weight of the system
s
Multimedia amplifier can be directly
incorporated on the motherboard using
surface mount components
40
20
Highly Integrated
Linear Amplifier
0
0
5
10
15
20
APPLICATION NOTE
AN-11
available on our web site
or call 1-800-LMI-7011
Audio sample from "Hold On Tight"
by Electric Light Orchestra
Seconds
PA C K A G E O R D E R I N F O
T
J
(°C)
0 to 70
Maximum
DB
Plastic SSOP
44-pin
VDD
15V
LX1720-01CDB
Note: Available in Tape & Reel.
Append the letter "T" to part number. (i.e. LX1720-01CDBT)
Copyright © 1999
Rev. 1.0 9/99
L
IN
F
INITY
M
ICROELECTRONICS
I
NC
.
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841, 714-898-8121, F
AX
: 714-893-2570
1
PRODUCT DATABOOK 1996/1997
LX1720
S
WITCHING
C
LASS
-D, S
TEREO
P
OWER
A
MPLIFIER
C
ONTROLLER
IC
P
R O D U C T I O N
AudioMAX
D
A T A
TM
S
H E E T
PA C K A G E P I N O U T S
RIS-
LIS-
IS+
RPWM
CPWM
CN
N.C.
CT
RT
RBIAS
GND
AGND
INPUT (R)
INPUT (L)
SLEEP
EAIN (R)
N.C.
EAOUT (R)
FAOUT (R)
EAOUT (L)
EAIN (L)
FAOUT (L)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
A B S O L U T E M A X I M U M R AT I N G S
(Note 1)
Supply Voltage (PVDD, VDD) ...................................................................... -0.3V to 18V
RPWM .................................................................................................... -0.3V to V
CN
+0.3V
INPUT (R), INPUT (L) .......................................................................... -0.3V to V
CN
+0.3V
FBK+(R), FBK-(R), FBK+(L), FBK-(L), SLEEP .............................................. -0.3V to V
DD
MUTE (R), MUTE (L) .................................................................................... -0.3V to 6.0V
EAOUT (R), EAOUT (L) ....................................................................... -0.3V to V
CN
+0.3V
CPWM, CT ............................................................................................. -0.3V to V
CN
+0.3V
IS+, LIS-, RIS+ ................................................................................................ V
DD
-2 to V
DD
Operating Junction Temperature
Plastic (DB Package) ............................................................................................ 125ºC
Storage Temperature Range ...................................................................... -65°C to 150°C
Lead Temperature (Soldering, 10 seconds) ............................................................ 300°C
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with
respect to Ground. Currents are positive into, negative out of the specified terminal.
T H E R M A L D ATA
DB PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
65°C/W
FBK- (R)
FBK+ (R)
N.C.
VDD
CP
PVDD
PGND
P- (R)
N- (R)
N+ (R)
P+ (R)
P- (L)
N- (L)
N+ (L)
P+ (L)
PGND
PVDD
FBK- (L)
FBK+ (L)
GND
MUTE (L)
MUTE (R)
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.
DB PACKAGE
(Top View)
FUNCTIONAL PIN DESCRIPTION
Pin Name
RIS-
LIS-
IS+
RPWM
CPWM
CN
CT
RT
RBIAS
GND
AGND
INPUT (R)
INPUT (L)
SLEEP
EAIN (R)
EAOUT (R)
Description
Right Channel Current Sense Input
Left Channel Current Sense Input
Positive Current Sense Input
PWM Resistor Connection
PWM Capacitor Connection
Supply Decoupling for NFET Drivers
Oscillator Timing Capacitor Connection
Oscillator Timing Resistor
Bias Setting Resistor for Error Amps
Ground (2-pins)
Audio Input Ground
Right Channel Input
Left Channel Input
Sleep Input
Inverting Input of Right Channel Error Amp
Right Channel Error Amplifier Output
Pin Name
FAOUT (R)
EAOUT (L)
EAIN (L)
FAOUT (L)
FBK+(R), FBK-(R)
CP
PVDD
VDD
PGND
P+(R), N+(R),
P-(R), N-(R)
P+(L), N+(L),
P-(L), N-(L)
FBK+(L), FBK-(L)
MUTE (R),
MUTE (L)
Description
Output of Right Feedback Amp
Left Channel Error Amplifier Output
Inverting Input of Left Channel Error Amp
Output of Left Feedback Amp
Right Channel Feedback Inputs
Supply Decoupling for PFET Drivers
Output Driver Supply Voltage (2-pins)
Analog Supply Voltage
IC Power Ground for the Output Drivers (2-pins)
Right Channel Gate Drive Outputs
Left Channel Gate Drive Outputs
Left Channel Feedback Inputs
Mute Inputs
2
Copyright © 1999
Rev. 1.0 9/99
PRODUCT DATABOOK 1996/1997
AudioMAX
TM
LX1720
S
WITCHING
C
LASS
-D, S
TEREO
P
OWER
A
MPLIFIER
C
ONTROLLER
IC
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C
≤
T
A
≤
70°C.
Test conditions: RT = 30k, CT = 100pF, VDD = PVDD = 15V.)
Parameter
Oscillator Section
Oscillator Frequency
Oscillator Peak Voltage
Oscillator Valley Voltage
Oscillator Max. Frequency
Voltage Stability
Temperature Stability
Symbol
Test Conditions
LX1720
Min. Typ.
280
330
2.5
200
1
1
2
5
60
7
Max.
380
Units
kHz
V
mV
MHz
%
%
mV
dB
MHz
V
mV
V
µA
V/V
kΩ
V
mV
dB
V
kΩ
mV/V
mV
nsec
nsec
µA
Ω
2
Error Amplifiers
Input Offset Voltage
DC Open Loop Gain
Unity Gain Bandwidth
High Output Voltage
Low Output Voltage
Input Common Mode Range
Input Bias Current
I
OUT
= -100µA
I
OUT
= +100µA
4
1
50
5
1
3.5
42
3.535
Input Amplifiers
Stage Gain
Input Impedance
Set by Internal Resistors
3.465
Feedback Amplifiers
High Output Voltage
Low Output Voltage
Common Mode Rejection
Input Common Mode Range
Input Impedance
Stage Gain
LX1720-01
I
OUT
= -250µA
I
OUT
= +250µA
4
50
70
0
Set by Internal Resistors
89
200
388
91
220
500
250
RPWM = 75k
75
20
V
DD
93
240
Current Limit Comparators
Voltage Sense Threshold
Comparator Response Time
PWM Comparators
CPWM Delay To Output
PWM Current Generator
CPWM Charge Current
Impedance of Internal Discharge FET
Output Drivers For The N-Channel MOSFETs
Ext. NFET Drivers, Low Level Voltage
Ext. NFET Drivers, High Level Voltage
V
OL
V
OH
I
SINK
= 3mA
I
SINK
= 75mA
I
SOURCE
= 3mA
I
SOURCE
= 75mA, CN = 5.2V (applied externally)
I
SINK
= 3mA
I
SINK
= 75mA
I
SOURCE
= 3mA
I
SOURCE
= 75mA, CP = 5.2V (applied externally)
30
1
30
1
30
1
30
1
100
1.5
100
1.5
100
1.5
100
1.5
mV
V
mV
V
mV
V
mV
V
Output Drivers For The P-Channel MOSFETs
Ext. PFET Drivers, Low Level Voltage
Ext. PFET Drivers, High Level Voltage
V
OL
V
OH
Copyright © 1999
Rev. 1.0 9/99
3
PRODUCT DATABOOK 1996/1997
LX1720
S
WITCHING
C
LASS
-D, S
TEREO
P
OWER
A
MPLIFIER
C
ONTROLLER
IC
P
R O D U C T I O N
AudioMAX
D
A T A
TM
S
H E E T
(Continued)
ELECTRICAL CHARACTERISTICS
Parameter
Undervoltage Lockout Section
Start Threshold Voltage
UV Lockout Hysteresis
UVLO Delay To Output Enable
Symbol
Test Conditions
LX1720
Min. Typ.
6.3
6.5
500
976
20
5
976
1.45
1.7
Max.
6.7
Units
V
mV
clkcyc
µA
mA
clkcyc
V
V
Supply Current
Sleep Current
Operating Current
Sleep To Output Enable
Sleep Threshold
SLEEP Input = 0V, T
A
= 25°C
SLEEP Input = 2V, V
IN
= 15V, No MOSFETs Connected
1.2
1.6
7
1.6
1.8
Mute Section
Mute Threshold
4
Copyright © 1999
Rev. 1.0 9/99
PRODUCT DATABOOK 1996/1997
AudioMAX
TM
LX1720
S
WITCHING
C
LASS
-D, S
TEREO
P
OWER
A
MPLIFIER
C
ONTROLLER
IC
P
R O D U C T I O N
D
A T A
S
H E E T
BLOCK DIAGRAM
R T
C T
S L E E P
R B IA S
V D D
C N
E A O U T (R )
E A IN (R )
S
Q
R
C L K
Q
E rro r A m p
F B K + (R )
F B K - (R )
F e e d b a c k
A m p
U V L O
V R E F
B IA S
O S C
C L K
P G N D
P V D D
V
R E G
C P
P - (R )
N - (R )
P + (R )
F A O U T (R )
IN P U T (R )
M U T E (R )
V D D
In p u t A m p
V D D
O U T
D R IV
A N
P R O T E
C IR C U
P U
E R
D
C T
IT
T
S
N + (R )
IO N
R Y
P - (L )
N - (L )
R P W M
C P W M
S
Q
R
E rro r A m p
C L K
Q
E A O U T (L )
E A IN (L )
F B K + (L )
F B K - (L )
F e e d b a c k
A m p
R IS -
L IS -
IS +
C L K
P + (L )
N + (L )
F A O U T (L )
IN P U T (L )
M U T E (L )
In p u t A m p
FIGURE 1
— LX1720 Block Diagram
Copyright © 1999
Rev. 1.0 9/99
5
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