MPQ7731
5W - 30W Class D Mono
Bridged Audio Amplifier
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MPQ7731 is a mono, 5W - 30W Class D
Audio Amplifier. It is one of MPS’ second
generation of fully integrated audio amplifiers which
dramatically reduces solution size by integrating
the following:
Start Up / Shut Down Pop Elimination
Short Circuit Protection Circuits
180mΩ Power MOSFETs
Mute / Standby Mode
The MPQ7731 utilizes a full bridge output
structure capable of delivering 5W - 30W into
4 speakers. As in all other MPS Class D
Audio Amplifiers, this device exhibits the high
fidelity of a Class AB amplifier with an efficiency
of 90%. The circuit is based on the MPS’
proprietary variable frequency topology Analog
Adaptive Modulation (AAM, Patent No.
6,420,930; other patents pending) that delivers
excellent PSRR, fast response time and
operates on a single power supply.
APPLICATIONS
EVALUATION BOARD REFERENCE
Board Number
Dimensions
EV0045
4.8cm x 3.0cm x 1.5cm
30W into 4Ω with VDD = 16.5V
90% Efficiency at 5W
Amplifies Full Audio Range with Low THD+N
Typical = 0.1%
9.5V to 18V Supply Voltage Operation
Full Bridge Output Drive
4 Integrated 180mΩ Switches
Turn On / Turn Off Click and Pop Suppression
Integrated Short Circuit Protection
Integrated Thermal shutdown
Mute / Standby Mode
Available in 20-Pin TSSOP Package
Flat Panel LCD and PDP Displays
Notebook and Multimedia Computers
Televisions
Home Stereos
DVD and VCD Players
Game Devices and Systems
Monitors
All MPS parts are lead-free, halogen free, and adhere to the RoHS
directive. For MPS green status, please visit MPS website under Quality
Assurance.
“MPS” and “The Future of Analog IC Technology” are Registered
Trademarks of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
THD+N vs Output Power
2
3
AUDIO IN+
4
5
6
7
AUDIO IN-
8
9
EN
10
NC
PGND1
PIN1
SW1
NIN1
VDD1
AGND1
NC
EN1
BS1
NC
PGND2
NIN2
SW2
PIN2
VDD2
AGND2
EN2
BS2
NC
+
VCC
20
19
18
17
16
VCC
15
14
13
12
11
VCC
VCC
+
THD+N (%)
VCC
MPQ7731
1
50
f=1kHz
20
10
5
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
1
10
50
OUTPUT POWER (W)
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
1
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature (TA)
MPQ7731DF
TSSOP20
MP7731DF
-40C to +85C
* For Tape & Reel, add suffix –Z (e.g. MPQ7731DF–Z).
For RoHS Compliant packaging, add suffix –LF (e.g. MPQ7731DF–LF–Z)
PACKAGE REFERENCE
NC
1
20
PGND1
PIN1
2
19
SW1
NIN1
3
18
VDD1
AGND1
4
17
BS1
NC
5
16
NC
EN1
6
15
PGND2
NIN2
7
14
SW2
PIN2
8
13
VDD2
AGND2
9
12
BS2
EN2
10
11
NC
MPQ7731
EXPOSED PAD
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage VDD............................................. 26V
BS Voltage ............................ VSW-0.3V to VSW+6.5V
Enable Voltage VEN................................. -0.3V to 6V
VSW, VPIN, VNIN .................................... -1V to VDD+1V
AGND to PGND................................... -0.3V to 0.3V
(2)
Continuous Power Dissipation (TA = +25°C)
………………………………………………....3.1W
Junction Temperature .....................................150˚C
Lead Temperature...........................................260˚C
Storage Temperature ....................... -65˚C to 150˚C
Recommended Operating Conditions
(3)
Supply Voltage VDD.................................9.5V to 18V
Operating Junct. Temp (TJ) ........... -40˚C to 125˚C
Thermal Resistance
(4)
θJA
θJC
TSSOP20 ................................40 ....... 6 .... C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
2
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
ELECTRICAL CHARACTERISTICS (5, 6)
VDD = 16.5V, VEN = 5V, RL = 4, TA = -40C To +85C, Typical values are at TA=25C , unless
otherwise noted.
Parameter
Standby Current
Symbol Condition
Min
VEN = 0V
Quiescent Current
Typ
Max
Units
2
10
3
6
A
mA
SW On Resistance
Sourcing and Sinking
0.18
Short Circuit Current
PIN, NIN Input Common Mode
Voltage Range
PIN, NIN Input Current
Sourcing and Sinking
5.0
EN Enable Threshold Voltage
0
VPIN=VNIN=8V
VEN Rising
EN Enable Input Current
VEN Falling
VEN = 5V
EN Enable Input Current
VEN Rising
Thermal Shutdown Trip Point
TJ Rising
Thermal Shutdown Hysteresis
0.4
TA = -40C To +85C
A
VDD/2
VDD-1.5
V
1
5
μA
1.4
2.0
V
1.2
1
1
5
V
μA
1
5
μA
150
C
30
C
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
3
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
OPERATING SPECIFICATIONS (7)
Circuit of Figure 1, VDD = 16.5V, VEN = 5V, RL = 4, TA = +25C, unless otherwise noted.
Parameter
Standby Current
Symbol Condition
Min
THD+ Noise
Efficiency
Maximum Power Bandwidth
Dynamic Range
Noise Floor
Power Supply Rejection
Max
Units
28
30
A
mA
W
17
W
0.2
%
POUT=1W, f=1kHz, RL=8
f=1kHz, POUT=10W
0.1
%
85
%
f=1kHz, POUT=10W, RL=8
88
%
A-Weighted
f=1kHz
20
90
370
60
kHz
dB
µV
dB
VEN = 0V
Quiescent Current
Power Output
Typ
f=1kHz, THD+N=10%
f=1kHz, THD+N=10%,
RL=8
POUT=1W, f=1kHz
700
Note:
5) The device is not guaranteed to function outside its operating rating.
6) Electrical Characteristics are for the IC only with no external components except bypass capacitors.
7) Operating Specifications are for the IC in Typical Application circuit (Figure 1).
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
4
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
TYPICAL PERFORMANCE CHARACTERISTICS
Circuit of Figure 1, VDD=16.5V, TA=25C, unless otherwise noted.
THD+N vs Output Power
20
10
5
20
10
5
20
10
5
2
1
0.5
0.2
0.1
0.05
1
10
OUTPUT POWER (W)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
50
1
10
OUTPUT POWER (W)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
50
THD+N vs Output Power
THD+N vs Output Power
50
20
10
5
20
10
5
20
10
5
50
50
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
Efficiency vs Output Power
FFT Noise Floor
VDD=12V
50
THD=10%
35
80
70
60
50
40
30
20
30
25
20
15
10
5
10
0
1
10
OUTPUT POWER (W)
40
90
10K20K
50
Output Power vs Supply Voltage
100
EFFICIENCY (%)
0
-10 16K FFT
-20 A-wtd
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
20
100
1K
FREQUENCY (Hz)
1
10
OUTPUT POWER (W)
OUTPUT POWER (W)
1
10
OUTPUT POWER (W)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
THD+N (%)
50
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100M
1
10
OUTPUT POWER (W)
THD+N vs Output Power
50
THD+N (%)
THD+N (%)
THD+N (%)
50
0.02
0.01
100M
AMPLITUDE (dBV)
THD+N vs Output Power
50
THD+N (%)
THD+N (%)
THD+N vs Output Power
50
0
5
10
15
20
OUTPUT POWER (W)
25
0
5
10
15
SUPPLY VOLTAGE (VDD)
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
20
5
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
PIN FUNCTIONS
Pin #
Name
1, 5, 11, 16
NC
2
PIN1
3
NIN1
4
AGND1
6
EN1
7
NIN2
8
PIN2
9
AGND2
10
EN2
12
BS2
13
VDD2
14
SW2
15
PGND2
17
BS1
18
VDD1
19
SW1
20
PGND1
Description
No Connect – Not internally connected
Amplifier 1 Positive Input. PIN1 is the positive side of the differential input to Amplifier 1.
Use a resistive voltage divider to set the voltage at PIN1 to VDD/2. See Figure 1.
Amplifier 1 Negative Input. NIN1 is the negative side of the differential input to Amplifier
1. See Figure 1.
Analog Ground 1. Connect AGND1 to AGND2.
Enable Input 1. EN1 must be connected to EN2. Drive high to enable MPQ7731, drive
low to disable.
Amplifier 2 Negative Input. NIN2 is the negative side of the differential input to Amplifier
2. See Figure 1.
Amplifier 2 Positive Input. PIN2 is the positive side of the differential input to Amplifier 2.
Use a resistive voltage divider to set the voltage at PIN2 to VDD/2. See Figure 1.
Analog Ground 2. Connect AGND2 to AGND1.
Enable Input 2. EN2 must be connected to EN1. Drive high to enable MPQ7731, drive
low to disable.
High-Side MOSFET Bootstrap Input for Amplifier 2. A capacitor from BS2 to SW2
supplies the gate drive current to the internal high-side MOSFET. Connect a 1μF
capacitor from SW2 to BS2. See Figure 1.
Power Supply Input. Bypass VDD2 to PGND2 with a 1μF X7R capacitor (in addition to
the main bulk capacitor), placed close to the IC PIN13 and PIN15.
Switched Power Output. SW2 is the output of Amplifier 2. Connect the LC filter to this
pin. See Figure 1.
Power Ground for Amplifier 2. Connect PGND2 to PGND1. See Figure 1.
High-Side MOSFET Bootstrap Input for Amplifier 1. A capacitor from BS1 to SW1
supplies the gate drive current to the internal high-side MOSFET. Connect a 1μF
capacitor from SW1 to BS1. See Figure 1.
Power Supply Input. Bypass VDD1 to PGND1 with a 1μF X7R capacitor (in addition to
the main bulk capacitor), placed close to the IC PIN18 and PIN20.
Switched Power Output. SW1 is the output of Amplifier 1. Connect the LC filter to this
pin. See Figure 1.
Power Ground for Amplifier 1. Connect PGND1 to PGND2. See Figure 1.
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
6
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
APPLICATION INFORMATION
COMPONENT SELECTION
The MPQ7731 uses a minimum number of
external components to complete a fully bridged
Class D audio amplifier. The circuit in Figure 1
shows a typical application. Use the following
sections to customize the amplifier for your
particular application.
Setting the Voltage Gain
The voltage gain sets the output voltage swing
for a given input voltage swing and is set by the
following equation:
R
A V 2 1
R4
Where:
R1 = R8
R4 = R6
The maximum output voltage swing is limited by
the power supply. The MPQ7731 is a bridged
amplifier and the output load is driven differentially.
Each side of the load is limited to a maximum
peak-to-peak voltage swing of approximately
VDD. To achieve the maximum output power of
the MPQ7731 amplifier, set the amplifier gain
such that the maximum peak-to-peak input
signal results in at least the maximum peak-topeak output voltage swing.
Setting the Switching Frequency
The idle switching frequency (the switching
frequency with no audio input signal) is a
function of the supply voltage, VDD, the capacitors
C14, C6 and C10 and resistors R1 and R8. Lower
switching frequencies result in more inductor
ripple, causing more quiescent output voltage
ripple, increasing the output noise.. Higher
switching frequencies result in more power loss.
The optimum quiescent switching frequency is
approximately 400kHz-600kHz. C6 and C14 are
typically 1pF to 2.2pF. C10 is used to program
the idle switching frequency.
Choosing the LC Filter
Two identical LC filters are required in the
typical application. The inductor-capacitor (LC)
filter is a second order filter that converts the
pulse train at SW (Pins 14, 19) to the output
differential signal that drives the speaker.
Typical values for the LC filters are shown in
Figure 1. The characteristic frequency of the LC
filter needs to be high enough to allow high
frequency audio to reach the output, yet needs
to be low enough to filter out high frequency
contents of the pulses from SW.
The characteristic frequency of the LC filter is:
1
f0
2 LC
Where:
L = L1 + L2, L1 = L2
C2 C17
C C9
, C2 = C17
C2 C17
The quality factor (Q) of the LC filter is
important. If this is too low, output noise will
increase. If the Q factor is too high, then
peaking may occur at high signal frequencies
reducing the pass-band flatness.
The Q is calculated as:
Q
R
L
C
Where R is the load (speaker) resistance.
Use an LC filter with a Q between 0.7 and 2.0.
The actual output ripple and noise is greatly
affected by the type of inductor and capacitor
used in the LC filter. Use a film capacitor and
an inductor with sufficient power handling
capability to supply the output current to the
load. The inductor should exhibit soft saturation
characteristics. If the inductor exhibits hard
saturation, it should operate well below the
saturation current. Gapped ferrite, MPP, Powdered
Iron, or similar type toroidal cores are
recommended. If open or shielded bobbin
ferrite cores are used, make sure that the start
windings of each inductor line up (all starts
going toward SW pin, or all starts going toward
the output) to prevent crosstalk or other
channel-to-channel interference.
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
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© 2015 MPS. All Rights Reserved.
7
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
Input Coupling Capacitor
The input coupling capacitors, C7 and C12, are
used to pass only the AC audio signal to the
input of the amplifier. In a typical system
application, the source input signal is typically
centered around the circuit ground, while the
MPQ7731 input is at half the power supply
voltage (VDD/2). The input coupling capacitor
transmits the AC signal from the source to the
MPQ7731 while blocking the DC voltage. This
input coupling capacitor creates a low-pass filter
with the input resistor of the MPQ7731. Choose
an input coupling capacitor such that the corner
frequency (fIN) is less than the desired passband frequency.
The formula for the corner frequency is:
f IN
1
2RC
Where:
R = R4 = R6
C = C7 = C12
Where fIN is the -3db cutoff frequency, R4 and
R6 are the input resistors and C7 and C12 are
the input AC coupling capacitors.
Power Source
For maximum output power, the amplifier circuit
requires a regulated external power source to
supply the power to the amplifier. The higher
the power supply voltage, the more power can
be delivered to a given load resistance. However,
if the power source voltage exceeds the maximum
operating voltage of 18V, the MPQ7731 may
sustain damage. The power supply rejection of the
MPQ7731 is excellent. However, noise at the
power supply can get to the output, so care
must be taken to minimize power supply noise
within the pass-band frequencies. Bypass the
power supply pins with a large electrolytic
capacitor (typically aluminum electrolytic) along
with smaller 1µF ceramic capacitors at the
MPQ7731 VDD supply pins.
Circuit Layout
Proper circuit layout is critical for optimum
performance and low output distortion and
noise. Place the following components as close
to the MPQ7731 as possible:
1. Power Supply Bypass, C5, C11.
C5 and C11 carry the transient current for
the switching power stage. Place a 1uF
power supply bypass capacitor as close to
Pin 18 (VDD1) and Pin 20 (PGND1) as
possible. Also place a 1uF power supply
bypass capacitor as close to Pin 13 (VDD2)
and Pin 15 (PGND2) as possible.
2. Output Catch Diodes, D2, D3, D5, and D6.
These diodes carry the current over the
dead-time while both MOSFET switches
are off. Place D3 between Pin 19 (SW1)
and Pin 20 (PGND1) to prevent the voltage
at SW1 from swinging excessively below
ground, and place D2 between SW1 and
pin 18 (VDD1) to prevent the voltage at SW1
from swinging excessively about VDD. Place
D6 and D5 similarly to minimize the undershoot and over-shoot of SW2 node.
3. Input Modulator Capacitor, C10.
C10 is used to set the amplifier switching
frequency. Place C10 as close to the
differential inputs, Pin 2 and Pin 3, as
possible to reduce distortion and noise.
Electro-Magnetic Interference (EMI)
Due to the switching nature of the Class-D
amplifier, care must be taken to minimize the
effects of electromagnetic interference from the
amplifier. However, with proper component
selection and careful attention to circuit layout,
the effects of the EMI due to the amplifier
switching can be minimized. The power inductors
are a potential source of radiated emissions. For
the best EMI performance, use shielded
inductors, since the magnetic field is well
contained inside the core. On the system
printed circuit board, trace loops that carry
rapidly changing currents need to be minimized.
VDD bypass capacitors (C5 and C11) must be
placed as close to the MPQ7731 as possible.
Nodes that carry rapidly changing voltage, such
as SW1 and SW2, must be made as small as
possible. If sensitive traces run near SW1 or
SW2, place a ground shield between the traces.
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
8
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
TYPICAL APPLICATION CIRCUIT
MPQ7731
Figure 1— Mono Full Bridged Circuit
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
9
MPQ7731 – 5W – 30W CLASS D MONO BRIDGED AUDIO AMPLIFIER
PACKAGE INFORMATION
TSSOP20F
(Exposed Paddle)
4.40
TYP
6.40
6.60
20
0.40
TYP
11
1.60
TYP
4.30
4.50
PIN 1 ID
1
0.65
BSC
3.20
TYP
6.20
6.60
5.80
TYP
10
TOP VIEW
RECOMMENDED LAND PATTERN
0.80
1.05
1.20 MAX
SEATING PLANE
0.19
0.30
0.65 BSC
0.00
0.15
0.09
0.20
SEE DETAIL "A"
SIDE VIEW
FRONT VIEW
GAUGE PLANE
0.25 BSC
3.80
4.30
0o-8o
0.45
0.75
DETAIL A
2.60
3.10
BOTTOM VIEW
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSION OR GATE BURR.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSION.
4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.10 MILLIMETERS MAX.
5) DRAWING CONFORMS TO JEDEC MO-153, VARIATION ACT.
6) DRAWING IS NOT TO SCALE.
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MPQ7731 Rev. 2.4
www.MonolithicPower.com
7/7/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
10
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