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TM
MP7782
50W Class D Mono Bridged Audio Amplifier
The Future of Analog IC Technology
TM
DESCRIPTION
The MP7782 is a mono, 50W Class D Audio Amplifier. It is one of MPS' second generation fully integrated audio amplifiers which dramatically reduces solution size by integrating four 180m power MOSFETs in a space saving TSSOP20 package. The MP7782 utilizes a full bridge output structure capable of delivering 50W into 6 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 ADAMTM (Analog Digital Adaptive Modulation), MPS' proprietary variable frequency modulation topology (patents pending) that delivers excellent PSRR, fast response time and operates on a single power supply.
FEATURES
* * * * * * * * * * * * 50W into 6 with VDD = 24V @10% THD+N 90% Efficiency at 50W Amplifies Full Audio Range with Low THD+N THD+N = 0.06% @ 1W 9.5V to 24V Supply Voltage Operation Full Bridge Output Drive 4 Integrated 180m Switches Turn-On / Turn-Off Click and Pop Suppression Integrated Short Circuit Protection Integrated Thermal Shutdown Mute / Standby Mode Thermally Enhanced 20-Pin TSSOP Package with Exposed Pad MP3 Systems Surround Sound Systems Multimedia Computers Televisions Home Stereos DVD and VCD Players Game Devices and Systems Subwoofers
APPLICATIONS
* * * * * * * *
EVALUATION BOARD REFERENCE
Board Number EV7782DF-00A Dimensions 4.0"X x 3.5"Y x 1.0"Z
"MPS" and "The Future of Analog IC Technology" are Trademarks of Monolithic Power Systems, Inc. ADAM (Analog Digital Adaptive Modulation) is a Trademark of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
MP7782
1 2 NC FB2 FB1 AGND NC EN FB2 FB1 AGND EN PGND1 SW1 VDD1 BS1 NC PGND2 SW2 VDD2 BS2 NC 20 19 18 17 16 15 14 13 12 11
VDD
+
100
AUDIO IN
3 4
10
+
GND
5 6 7 8 9
THD+N (%)
-
1
0.1
EN OFF ON
10
0.01 0.1
MP7782-TAC01
1 10 OUTPUT POWER (W)
100
MP7782-EC01
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER
PACKAGE REFERENCE
TOP VIEW
NC* FB2 FB1 AGND NC* EN FB2 FB1 AGND EN 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 PGND1 SW1 VDD1 BS1 NC* PGND2 SW2 VDD2 BS2 NC*
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, VFB2, VFB1 ...........................-1V to VDD + 1V AGND to PGND .......................... -0.3V to +0.3V Junction Temperature...............................150C Lead Temperature ....................................260C Storage Temperature .............. -65C to +150C
Recommended Operating Conditions
(2)
Supply Voltage VDD .......................... 9.5V to 24V Operating Temperature TA......... -40C to +85C
Thermal Resistance
(3)
TSSOP20F ............................. 40 ....... 6.... C/W
Notes: 1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions. 3) Measured on approximately 1" square of 1 oz copper.
JA
JC
EXPOSED PAD
* ALL NC PINS SHOULD BE GROUNDED IN LAYOUT
MP7782_PD01-TSSOP20F
Part Number* MP7782DF *
Package TSSOP20F
Temperature -40C to +85C
For Tape & Reel, add suffix -Z (eg. MP7782DF-Z) For Lead Free, add suffix -LF (eg. MP7782DF-LF-Z)
ELECTRICAL CHARACTERISTICS
(VDD = 24V, VEN = 5V, TA = +25C, unless otherwise noted.)
Parameter Supply Current Standby Current Quiescent Current Output Drivers SW On Resistance Short Circuit Current Inputs FB1, FB2 Input Common Mode Voltage Range FB1, FB2 Input Current EN Enable Threshold Voltage EN Enable Input Current Thermal Shutdown Thermal Shutdown Trip Point Thermal Shutdown Hysteresis Symbol Condition VEN = 0V Min Typ 2 3 0.18 5.0 0 VFB2 = VFB1 = 8V VEN Rising VEN Falling VEN = 5V TJ Rising 0.4 VDD/2 1 1.4 1.2 1 150 30 VDD-1.5 5 2.0 Max 10 6 Units A mA A V A V V A C C
Sourcing and Sinking Sourcing and Sinking
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER
OPERATING SPECIFICATIONS
(Circuit of Figure 1, VDD = 24V, VEN = 5V, TA = +25C, unless otherwise noted.)
Parameter Standby Current Quiescent Current Power Output THD+ Noise Efficiency Dynamic Range Noise Floor Power Supply Rejection Condition VEN = 0V f = 1KHz, THD+N = 10%, RL = 6 f = 1KHz, THD+N = 10%, RL = 8 POUT = 1W, f = 1KHz, RL = 6 POUT = 1W, f = 1KHz, RL = 8 f = 1KHz, POUT = 50W A-Weighted f = 1KHz Min Typ 700 28 50 40 0.06 0.08 90 100 187 60 Max Units A mA W % % dB V dB
PIN FUNCTIONS
Pin # 1, 5, 11, 16 3, 8 2, 7 4, 9 6, 10 12 13 14 15 17 18 19 20 Name NC FB1 FB2 AGND EN BS2 VDD2 SW2 PGND2 BS1 VDD1 SW1 PGND1 Description No Connect. Not internally connected. First Feedback. Receives feedback from SW1 via resistor(s) and the positive input signal via resistor and capacitor. Both pins must be tied together. Second Feedback. Receives feedback from SW2 via resistor(s) and the negative input signal via resistor and capacitor. Both pins must be tied together. Analog Ground. Both pins must be tied together. Enable Input. Drive high to enable the MP7782, drive low to disable it. Both pins must be tied together. High-Side MOSFET Bootstrap Input for Channel 2. A capacitor from BS2 to SW2 supplies the gate drive current to the internal high-side MOSFET. Connect a 1F capacitor from SW2 to BS2. See Figure 1. Power Supply Input. Bypass VDD2 to PGND2 with a 1F X7R capacitor (in addition to the main bulk capacitor), placed close to pins 13 and 15. Switched Power Output. SW2 is the output of Channel 2. Connect the LC filter to this pin. See Figure 1. Power Ground for Channel 2. Connect PGND2 to PGND1. See Figure 1. High-Side MOSFET Bootstrap Input for Channel 1. A capacitor from BS1 to SW1 supplies the gate drive current to the internal high-side MOSFET. Connect a 1F capacitor from SW1 to BS1. See Figure 1. Power Supply Input. Bypass VDD1 to PGND1 with a 1F X7R capacitor (in addition to the main bulk capacitor), placed close to pins 18 and 20. Switched Power Output. SW1 is the output of Channel 1. Connect the LC filter to this pin. See Figure 1. Power Ground for Channel 1. Connect PGND1 to PGND2. See Figure 1.
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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TM
MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER
TYPICAL PERFORMANCE CHARACTERISTICS
Circuit of Figure 1, VDD = 24V, TA = +25C
100
-20 -40
+18 +14 +10 +6
10
-60
THD+N (%)
GAIN (dBr)
10K
MP7782-TPC02
-80 1 f=1KHz 0.1
A-Weighted
(dBV)
+2 -2 -6 -10 -14 -18 -22
-100 -120 -140 -160
0.01 0.1 1 10 OUTPUT POWER (W) 100
-180
100 1K FREQUENCY (Hz)
20
100 1k FREQUENCY (Hz)
10k
MP7782-TPC03
MP7782-EC01
100
100
10
THD+N (%) THD+N (%)
10
1 POUT=1W
1 POUT=1W
0.1
0.1
0.01 20 100 1k FREQUENCY (Hz) 10k
MP7782-TPC04
0.01 20 100 1k FREQUENCY (Hz) 10k
MP7782-TPC05
100
-20 -40
+18 +14 +10 +6 A-Weighted
GAIN (dBr)
10
THD+N (%) (dBV)
-60 -80
+2 -2 -6 -10 -14 -18 -22
1 f=1KHz 0.1
-100 -120 -140 -160
0.01 0.1 1 10 OUTPUT POWER (W) 100
-180
100 1K FREQUENCY (Hz)
10K
MP7782-TPC07
20
100 1k FREQUENCY (Hz)
10k
MP7782-TPC08
MP7782-TPC06
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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TM
MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER
TYPICAL APPLICATION CIRCUIT
C1 27pF
C10 1pF C6 1F 16V AUDIO IN GND
MP7782
1 2 NC FB2 FB1 AGND NC EN FB2 FB1 AGND EN PGND1 SW1 VDD1 BS1 NC PGND2 SW2 VDD2 BS2 NC 20 19 18 17 16 15 14 13 12 11
VDD
+
C2 1000F 35V
D3B OPTIONAL D2 6.2V D3A MBRS130LTR C15 390pF D5B OPTIONAL
L1 15H
C4 2.2nF
3 4 5
C3 1F 25V
C5 1F
C9 1F 16V
6 7 8 9
D1 1N4148 C8 1F 25V
C7 0.22F 50V L2 = L1 15H
C30 0.47F 50V +
C11 1F
D4 6.2V
D5A MBRS130LTR C16 390pF C12 0.22F 50V
EN OFF ON
10
C13 1pF
D6 1N4148
C14 27pF
MP7782_F01
Figure 1 -- 50W Class D BTL Amplifier (VDD = 24V)
APPLICATION INFORMATION
COMPONENT SELECTION
The MP7782 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:
AV = R1 R3
The maximum output voltage swing is limited by the power supply. The MP7782 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 approximately equal to VDD. To achieve the maximum output power of the MP7782 amplifier, set the amplifier gain such that the maximum peak-to-peak input signal results in at least the maximum peak-to-peak 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, capacitors C4, C10 and C13 and resistors R1, R3, R4 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 to 600KHz. C10 and C13 are typically 1pF to 2.2pF. C4 is used to program the idle switching frequency.
R8 = R1 R 4 = R3
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER Input Coupling Capacitor The input coupling capacitors, C6 and C9, 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 usually centered around the circuit ground, while the MP7782 input is at half the power supply voltage (VDD/2). The input coupling capacitor transmits the AC signal from the source to the MP7782 while blocking the DC voltage. This input coupling capacitor creates a low-pass filter with the input resistor of the MP7782. 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:
fIN = 1 2 x R3 x C6 R 4 = R3
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:
f0 = 1 2 LC
where:
L = L1 + L2 , L1 = L2 C7 x C12 C = C30 + , C7 = C12 C7 + C12
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 value is calculated as:
Q= R L C
C9 = C6
Where fIN is the -3dB cutoff frequency, R3 and R6 are the input resistors and C6 and C9 are the input AC coupling capacitors. Power Source For maximum output power, the amplifier circuit requires a regulated external power source to supply power to the amplifier. The higher the power supply voltage provided, the more power that can be delivered to a given load resistance. However, if the power source voltage exceeds the maximum operating voltage of 24V, the MP7782 may sustain damage. The power supply rejection of the MP7782 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 passband frequencies. Bypass the power supply pins with a large electrolytic capacitor (typically aluminum electrolytic) along with smaller 1F ceramic capacitors at the MP7782 VDD supply pins.
Where R is the load (speaker) resistance. Use an LC filter with a Q between 0.7 and 2. 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.
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER On the system printed circuit board, trace loops that carry rapidly changing currents need to be minimized. VDD bypass capacitors (C3 and C8) must be placed as close to the MP7782 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. Power Dissipation and Thermal Considerations The power dissipation of the MP7782 arises mostly from the conduction loss of the internal main switches. This power loss is estimated to be:
PLOSS POUT x 2 x 0.18 x 1.3 RL
Circuit Layout Proper circuit layout is critical for optimum performance and low output distortion and noise. Place the following components as close to the MP7782 as possible: 1. Power Supply Bypass, C3, C8 C3 and C8 carry the transient current for the switching power stage. Place a 1F power supply bypass capacitor as close to pin 18 (VDD1) and pin 20 (PGND1) as possible. Also place a 1F power supply bypass capacitor as close to pin 13 (VDD2) and pin 15 (PGND2) as possible. 2. Output Catch Diodes, D3A, D3B, D5A, D5B D3A, D3B, D5A, and D5B carry the current over the dead-time while the MOSFET switches are off. Place D3A between pin 19 (SW1) and pin 20 (PGND1) to prevent the voltage at SW1 from swinging excessively below ground, and place D3B between SW2 and pin 18 (VDD1) to prevent the voltage at SW1 from swinging excessively above VDD. Place D5A and D5B similarly to minimize the overshoot and undershoot of SW2 node. 3. Input Modulator Capacitors, C4 C4 is used to set the amplifier switching frequency. Place C4 as close to the differential inputs, pin 2 and pin 3, as possible to reduce distortion and noise. 4. 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 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.
Where 1.3 is a temperature coefficient factor that reflects the increase in the RDS(ON) resistance at elevated temperatures. For example, for a 6 speaker, the max POUT is 50W:
PLOSS 50 x 2 x 0.18 x 1.3 = 3.9 W 6
Because the thermal resistance JC is 6C/W, the resulting temperature rise between junction and case is approximately 24C. Therefore, caution must be exercised when using the MP7782 in applications with continuous high output power. A heat sink is required if the MP7782 is applied at continuous 50W output power.
MP7782 Rev. 1.2 8/3/2005
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
7
TM
MP7782 - 50W CLASS D MONO BRIDGED AUDIO AMPLIFIER
PACKAGE INFORMATION
TSSOP20F (EXPOSED PAD)
0.0256(0.650)TYP 0.004(0.090) 0.010(0.250) GATE PLANE 0.169 0.177 (4.300) (4.500) 0.244 0.260 (6.200) (6.600) 0.004(0.090) 0o-8o 0.018(0.450) 0.030(0.750) 0.039(1.000)REF
0.105 (2.67) 0.118 (3.00) pad width 0.030(0.750)
DETAIL "A"
SEE DETAIL "B"
PIN 1 IDENT. 0.030(0.750) 0.150 (3.80) 0.165 (4.19) pad length 0.252 (6.400) 0.260 (6.600) 0.047(1.200) max 0.007(0.190) 0.012(0.300) 0.032(0.800) 0.041(1.050)
SEE DETAIL "A"
0.075(0.190) 0.012(0.300) SEATING PLANE 0.004(0.090) 0.006(0.160) 0.004(0.090) 0.008(0.200)
0.002(0.050) 0.006(0.150)
NOTE: 1) Control dimension is in inches. Dimension in bracket is millimeters.
0.007(0.190) 0.010(0.250)
DETAIL "B"
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications. 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.
MP7782 Rev. 1.2 8/3/2005 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2005 MPS. All Rights Reserved.
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