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Datasheet File OCR Text:

19-5286; Rev 0; 6/10
TION KIT EVALUA BLE AVAILA
Stereo, High-Power, Class D Amplifiers
General Description Features
S Wide 8V to 28V Supply Voltage Range S Single-Supply Operation S Low EMI: Active Emissions Limiting S Clipping Limiter S Low Quiescent Current S Thermal Foldback S Thermal and Overcurrent Protection
MAX98400A/MAX98400B
The MAX98400A/MAX98400B Class D amplifiers provide high-performance, thermally efficient amplifier solutions. The MAX98400A delivers 2x20W into 8I loads or 1x40W into a 4I load. The MAX98400B delivers 2x12W into 8I loads. An integrated limiting circuit prevents output clipping distortion, protects small speakers from transient voltages, and reduces power dissipation. A thermal-foldback feature can be enabled to automatically reduce the output power at above a junction temperature of +120NC. Traditional thermal protection is also available in addition to robust overcurrent protection. The ICs operate from a single 8V to 28V supply and provide a high 67dB PSRR, eliminating the need for a regulated power supply. They offer up to 90% efficiency from a 12V supply. Filterless modulation allows the ICs to pass EN55022B EMI limits with 1m cables using only a low-cost ferrite bead and small-value capacitor on each output. Both devices feature eight digitally controlled gain settings. Comprehensive click-and-pop reduction circuitry minimizes noise coming into and out of shutdown. The MAX98400A/MAX98400B are available in 36-pin and 24-pin TQFN packages, respectively, and are specified over the -40NC to +85NC temperature range.
Applications
LCD/PDP Televisions LCD Monitors MP3 Docking Stations Notebook PCs
Ordering Information
PART MAX98400AETX+ MAX98400BETG+ PIN-PACKAGE 36 TQFN-EP* 24 TQFN-EP* SPEC 2x20W 2x12W
Note: Devices operate over the -40C to +85C temperature range. *EP = Exposed pad.
Simplified Block Diagram
INLCLIPPING LIMITER PGA CLASS D MODULATOR AND H-BRIDGE
OUTL-
INL+
OUTL+ MONO*
MAX98400A/B
INRCLIPPING LIMITER PGA CLASS D MODULATOR AND H-BRIDGE OUTR-
INR+
OUTR+
*MAX98400A ONLY
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Table of ConTenTs
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Stereo Configuration for MAX98400A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Mono Configuration for MAX98400A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Click-and-Pop Suppression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Mono Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Clipping Limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Limiter Threshold Control (LIM_TH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Release Time Control (RELEASE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Preamplifier Gain Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Overtemperature Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Applications Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Filterless Class D Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Inductor-Based Output Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Component Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Input Capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Internal Regulator VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Supply Bypassing, Layout, and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Chip Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Functional Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Package Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
lisT of figures
Figure 1. MAX98400B EMI Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 2. MAX98400A Efficiency vs. Class AB Effifciency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 3. Limiter Control, Mode3 Configuration (Table 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 4. Output Filter for PWM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
lisT of Tables
Table 1. Limiter Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Table 2. Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Table 3. Filter Component Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
ABSOLUTE MAXIMUM RATINGS
PVDD to PGND......................................................-0.3V to +30V VS to GND ...............................................................-0.3V to +6V SHDN, MONO to GND ............................................-0.3V to +6V IN_ to GND ..............................................................-0.3V to +6V G1, G2, RELEASE, TEMPLOCK, LIM_TH to GND ........................................ -0.3V to (VS + 0.3V) OUT_ to PGND ......................................-0.3V to (VPVDD + 0.3V) PGND to GND ......................................................-0.3V to +0.3V Continuous Current into OUT_ .......................................... +2.4A Continuous Current into PVDD, PGND ............................. +4.8A Continuous Current into All Other Pins ........................... +10mA Duration of OUT_ Short Circuit to PVDD or PGND ...Continuous Duration of Short Circuit Between OUT_+ and OUT_- .................................................Continuous Continuous Power Dissipation (TA = +70NC) 36-Pin TQFN Multilayer Board (derate 35.7mW/NC above +70NC) .........................2857.1mW BJA (Note 1) .............................................................28NC/W BJC (Note 1) ...............................................................1NC/W 24-Pin TQFN Multilayer Board (derate 27.8mW/NC above +70NC) .............................35.7mW BJA (Note 1) .............................................................36NC/W BJC (Note 1) ...............................................................3NC/W Junction Temperature .....................................................+150NC Operating Temperature Range .......................... -40NC to +85NC Storage Temperature Range............................ -65NC to +150NC Lead Temperature (soldering, 10s) ................................+300NC Soldering Temperature (reflow) ......................................+260NC
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL ChARACTERISTICS
(VPVDD = 18V, CIN = 1FF, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CREL = 1FF, C1 = C2 = 1FF, RL = J, AC measurement bandwidth 20Hz to 20kHz, differential input signal, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 2, 3) PARAMETER PVDD Supply Voltage Range VS Supply Input Voltage Quiescent Current Single-Supply Quiescent Current Shutdown Current PVDD Undervoltage Lockout VS Regulator Output Voltage INPUT STAGE Differential Input Voltage Range Single-Ended Input Voltage Range Common-Mode Rejection Ratio Input Resistance CMRR Differential VLIM_TH = 0V, gain = +35dB 20 60 32 2 1 VRMS VRMS dB kI SYMBOL VPVDD VS IPVDD IVS IPVDD ISHDN_PVDD ISHDN_VS VUVLO VS CONDITIONS Inferred from PVDD_PSRR Inferred from IVS test Dual-supply mode: VS = 4.75V, TA = +25NC Single-supply mode: TA = +25NC RL = 8I (Note 3) VSHDN = 0V, TA = +25NC, VS = 5.5V 4.2 MIN 8 4.75 10 6 16 17 8 3 7 4.47 20 10 7.9 4.75 FA V V TYP MAX 28 5.5 15 8.2 23 UNITS V V mA AMPLIFIER DC ChARACTERISTICS
mA
4
Stereo, High-Power, Class D Amplifiers
ELECTRICAL ChARACTERISTICS (continued)
(VPVDD = 18V, CIN = 1FF, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CREL = 1FF, C1 = C2 = 1FF, RL = J, AC measurement bandwidth 20Hz to 20kHz, differential input signal, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 2, 3) PARAMETER POWER STAGE Shutdown to Full Operation Gain Accuracy Left-to-Right Gain Matching Crosstalk Output Offset Voltage VOS All gain settings 1kHz 10kHz TA = +25NC Peak voltage, 32 samples/s, A-weighted, TA = +25NC (Notes 4, 5) VPVDD = 8V to 28V PSRRPVDD 1kHz, 100mVP-P ripple 10kHz, 100mVP-P ripple VS = 4.75V to 5.5V VS Power-Supply Rejection Ratio PSRRVS 1kHz, 100mVP-P ripple 10kHz, 100mVP-P ripple Stereo, RL = 8I, 10% THD+N, fIN = 1kHz (Note 3) Mono, RL = 4I, 10% THD+N, fIN = 1kHz (Note 3) Stereo, RL = 8I, 10% THD+N, fIN = 1kHz (Note 3) POUT = 0.1W to POUT/2, fIN = 20Hz to 20kHz, RL = 8I POUT/2, fIN = 1kHz, RL = 8I VN E ILIM RDSON fSW VPVDD = 28V VLIM_TH = 0V VLIM_TH = 0V VPVDD = 14V (Note 6) (Note 7) VLIM_TH = 0V VLIM_TH = 0V A-weighted POUT = 2x20W, RL = 8I (MAX98400A) fIN = 1kHz (Note 3) 3.5 265 20 39 Into shutdown Out of shutdown 52 -85 -68 Q8 -47 dBV -56 63 67 57 55 50 40 22 44 15 0.3 0.03 100 90 5 0.4 330 26 240 0.8 4 -1 -12 0 -6 +1 FVRMS % A 395 I kHz V Fs s dBFS dBFS dBFS dB 5 W dB dB Q45 tSON Q0.8 11 Q4 Q2 ms % % dB mV SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX98400A/MAX98400B
Click-and-Pop Level
KCP
PVDD Power-Supply Rejection Ratio
MAX98400A Output Power
POUT
MAX98400B Output Power Total Harmonic Distortion Plus Noise Output Noise Efficiency Current Limit Output FET Resistance Switching Frequency Peak Output Voltage LIMITER Attack Time Release Time Maximum Trigger Level Minimum Trigger Level Trigger Level Compression Range
POUT
THD+N
%
500
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
ELECTRICAL ChARACTERISTICS (continued)
(VPVDD = 18V, CIN = 1FF, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CREL = 1FF, C1 = C2 = 1FF, RL = J, AC measurement bandwidth 20Hz to 20kHz, differential input signal, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 2, 3) PARAMETER VGA Distortion LIM_TH Input-Voltage Low (PVDD Tracking) LIM_TH Input-Voltage High (Limiter Off) Channel-to-Channel Attenuation Tracking ThERMAL FOLDBACK Internal Templock Resistor Trigger Temperature Hard Thermal Protection LOGIC INPUT (G1, G2) Sink Current Source Current Input High Threshold Input Low Threshold Input Three-State Window LOGIC INPUT (SHDN, MONO (MAX98400A Only)) Input Leakage Current IIN TA = +25NC Input High Threshold VINH Input Low Threshold Input-Voltage Hysteresis VINL 100 0.3 x VS 0.45 x VS 0.5 x VS 0.55 x VS Q10 2 0.4 TA = +25NC, VG1, VG2 = 0V TA = +25NC, VG1, VG2 = VS 120 205 +130 +165 +5 -5 310 kI NC NC FA FA V V V Q1 SYMBOL CONDITIONS Compression = 0 to -12dB 0.15 VS -1 MIN TYP 3.5 MAX UNITS % V V dB
+2.5 -8
+8 -2.5 0.8 x VS
FA V V mV
Note 2: 100% production tested at TA = +25NC. Specifications over temperature limits are guaranteed by design. Note 3: The MAX98400A stereo mode is specified with an 8I resistive load in series with a 68FH inductive load connected across BTL outputs. The MAX98400A mono mode is specified with a 4I resistive load in series with 33FH inductive load. The MAX98400B is specified with an 8I resistive load in series with a 68FH inductive load connected across BTL outputs. Note 4: Amplifier inputs AC-coupled to GND. Note 5: Mode transitions controlled by SHDN. Note 6: Relative to equivalent full-scale undistorted output. Full scale (FS) = VPVDD x 0.95. Note 7: Relative to equivalent full-scale undistorted output. Full scale (FS) = VPVDD.
6
Stereo, High-Power, Class D Amplifiers
Typical Operating Characteristics
(MAX98400A, VPVDD = 18V, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CIN = CREL = C1 = C2 = 1FF, typical values are at TA = +25NC, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX98400 toc01
MAX98400A/MAX98400B
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX98400 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX98400 toc03
1
1
1
0.1 THD+N (%)
POUT = 4W THD+N (%)
0.1 POUT = 7W THD+N (%)
0.1 POUT = 10W 0.01 POUT = 1W POUT = 1W 0.001 100 0.01 0.1 1 FREQUENCY (kHz)
POUT = 0.5W 0.01
0.01
0.001 0.01 0.1 1 FREQUENCY (kHz)
VPVDD = 12V 8I LOAD 10 100
0.001 0.01 0.1 1 FREQUENCY (kHz)
VPVDD = 12V 4I LOAD 10
VPVDD = 18V 8I LOAD 10 100
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX98400 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX98400 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX98400 toc06
10
10
10
1 THD+N (%)
f = 6kHz THD+N (%)
1
f = 6kHz THD+N (%)
1
f = 6kHz
0.1
f = 1kHz
0.1
f = 1kHz
0.1
f = 1kHz VPVDD = 24V RL = 8I STOPS BEFORE 10% THD+N DUE TO THERMAL LIMITING OF THERMAL FOLDBACK FEATURE 16 24 32 40 48
0.01 f = 100Hz 0.001 0 2 4 6 8 VPVDD = 12V 8I LOAD 10 12
0.01 f = 100Hz 0.001 0 4 8 12 16 VPVDD = 18V 8I LOAD 20 24
0.01 f = 100Hz 0.001 0 8
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX98400 toc07
EFFICIENCY vs. OUTPUT POWER
MAX98400 toc08
EFFICIENCY vs. OUTPUT POWER
90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 5 10 15
MAX98400 toc09
10
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20
100
1 THD+N (%)
f = 6kHz
0.1
f = 1kHz
0.01 f = 100Hz 0.001 0 2 4 6 8 10 12 VPVDD = 12V 4I LOAD 14 16 18
10 0 0 2 4 6 8
VPVDD = 12V, 8I LOAD, BOTH CHANNELS DRIVEN 10 12 14 16 18 20 TOTAL OUTPUT POWER (W)
VPVDD = 18V, 8I LOAD, BOTH CHANNELS DRIVEN 20 25 30 35 40 TOTAL OUTPUT POWER (W)
OUTPUT POWER (W)
7
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Typical Operating Characteristics (continued)
(MAX98400A, VPVDD = 18V, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CIN = CREL = C1 = C2 = 1FF, typical values are at TA = +25NC, unless otherwise noted.)
EFFICIENCY vs. OUTPUT POWER
MAX98400 toc10
EFFICIENCY vs. OUTPUT POWER
MAX98400 toc11
MAXIMUM OUTPUT POWER vs. SUPPLY VOLTAGE (WITH THERMAL SHUTDOWN)
90 MAXIMUM OUTPUT POWER (W) 80 70 60 50 40 30 20 10 0 8 12 16 20 24 28 SUPPLY VOLTAGE (V) 10% THD+N 1% THD+N 8I LOAD, BOTH CHANNELS ARE DRIVEN
MAX98400 toc12
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 10 20 VPVDD = 24V, 8I LOAD, BOTH CHANNELS DRIVEN 30 40 50
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 10 VPVDD = 12V, 4I LOAD, BOTH CHANNELS DRIVEN 20 30
100
60
40
TOTAL OUTPUT POWER (W)
TOTAL OUTPUT POWER (W)
MAXIMUM OUTPUT POWER vs. SUPPLY VOLTAGE (WITH THERMAL SHUTDOWN)
4I LOAD, BOTH CHANNELS ARE DRIVEN
MAX98400 toc13
OUTPUT POWER vs. LOAD
MAX98400 toc14
OUTPUT POWER vs. LOAD
45 40 35 POUT (W) 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 LOAD (I) 1% THD+N 10% THD+N VPVDD = 18V
MAX98400 toc15
60 MAXIMUM OUTPUT POWER (W) 50 40
40 35 30 POUT (W) 25 20 15 10 10% THD+N
VPVDD = 12V
50
30 20 10 0 8
10% THD+N 1% THD+N
5 0 10 12 SUPPLY VOLTAGE (V) 14 16 0 1% THD+N 10 20 30 40 50 60 70 80 90 100 LOAD (I)
OUTPUT POWER vs. LOAD
MAX98400 toc16
POWER-SUPPLY REJECTION RATIO
MAX98400 toc17
CROSSTALK vs. FREQUENCY
8I LOAD, POUT = 1W, f = 1kHz
MAX98400 toc18
80 70 60 POUT (W) 50 40 30 20 10 0 0 1% THD+N 10% THD+N
VPVDD = 24V
10 0 -10 -20 PSRR (dB) -30 -40 -50 -60 -70 -80
20 0 CROSSTALK (dB) -20 -40 -60 -80 -100
100mVP-P RIPPLE
10 20 30 40 50 60 70 80 90 100 LOAD (I)
0.01
0.1
1 FREQUENCY (kHz)
10
100
0.01
0.1
1 FREQUENCY (kHz)
10
100
8
Stereo, High-Power, Class D Amplifiers
Typical Operating Characteristics (continued)
(MAX98400A, VPVDD = 18V, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CIN = CREL = C1 = C2 = 1FF, typical values are at TA = +25NC, unless otherwise noted.)
INBAND OUTPUT SPECTRUM
MAX98400 toc19
MAX98400A/MAX98400B
WIDEBAND OUTPUT SPECTRUM
RBW = 100Hz -20 OUTPUT AMPLITUDE (dBV) -40 -60 -80 -100 -120 0.1 1 10 100
MAX98400 toc20
SHDN ON/OFF RESPONSE
MAX98400 toc21
0 8I LOAD -20 OUTPUT AMPLITUDE (dBV) -40 -60 -80 -100 -120 0 5 10 FREQUENCY (kHz) 15
0
SHDN 2V/div
OUTPUT 2V/div
20
4ms/div
FREQUENCY (MHz)
SUPPLY CURRENT vs. PVDD SUPPLY VOLTAGE
MAX98400 toc22
SUPPLY CURRENT vs. VS SUPPLY VOLTAGE
MAX98400 toc23
SHUTDOWN CURRENT vs. PVDD SUPPLY VOLTAGE
12 SHUTDOWN CURRENT (A) 10 8 6 4 2 IPVDD_SHDN
MAX98400 toc24
14 12 SUPPLY CURRENT (mA) IPVDD 10 8 6 4 2 VS = 5V 0 8 12 16 20 24 IVS
14 12 SUPPLY CURRENT (mA) 10 8 6 4 2 VPVDD = 18V 0 IVS IPVDD
14
IVS_SHDN VS = 5V
28
4.75
5.00
5.25
5.50
0 8 12 16 20 24 28 PVDD SUPPLY VOLTAGE (V)
PVDD SUPPLY VOLTAGE (V)
VS SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT vs. VS SUPPLY VOLTAGE
MAX98400 toc25
MAXIMUM OUTPUT POWER vs. PVDD (NO THERMAL SHUTDOWN)
MAX98400 toc26
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MONO)
MAX98400 toc27
14 12 SHUTDOWN CURRENT (A) 10 8 6 4 2 0 4.75 5.00 5.25 IPVDD_SHDN
60 50 MAXIMUM POUT (W) 40 30 4I LOAD 20 10 0 8 12 16 20 24 THERMAL FOLDBACK DISABLED, BOTH CHANNELS DRIVEN
1
8I LOAD
POUT = 8W 0.1 THD+N (%)
POUT = 1W 0.01
IVS_SHDN VPVDD = 18V 5.50
28
0.001 0.01 0.1 1 FREQUENCY (kHz)
VPVDD = 12V 4I LOAD 10 100
VS SUPPLY VOLTAGE (V)
PVDD SUPPLY VOLTAGE (V)
9
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Typical Operating Characteristics (continued)
(MAX98400A, VPVDD = 18V, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CIN = CREL = C1 = C2 = 1FF, typical values are at TA = +25NC, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (MONO)
MAX98400 toc28
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (MONO)
MAX98400 toc29
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (MONO)
MAX98400 toc30
10
10
10
1 THD+N (%)
f = 6kHz THD+N (%)
1
f = 6kHz THD+N (%)
1
f = 6kHz
0.1
f = 1kHz
0.1
f = 1kHz
0.1
f = 1kHz
0.01 f = 100Hz 0.001 0 4 8 12 VPVDD = 12V, 4I LOAD 16 20 24
0.01 f = 100Hz 0 8 16 24 VPVDD = 18V, 4I LOAD 32 40 48
0.01 f = 100Hz 0.001 0 10 20 30 40 50 VPVDD = 24V, 4I LOAD 60 70 80
0.001
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
EFFICIENCY vs. OUTPUT POWER (MONO)
MAX98400 toc31
EFFICIENCY vs. OUTPUT POWER (MONO)
MAX98400 toc32
EFFICIENCY vs. OUTPUT POWER (MONO)
90 80 EFFICIENCY (%) 70 60 50 40 30 20
MAX98400 toc33
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 5 10 VPVDD = 12V, 4I LOAD 15
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 VPVDD = 18V, 4I LOAD 0 5 10 15 20 25 30 35
100
10 0 40 0 5 10 15 20 25
VPVDD = 24V, 4I LOAD 30 35 40
20
TOTAL OUTPUT POWER (W)
TOTAL OUTPUT POWER (W)
TOTAL OUTPUT POWER (W)
MAXIMUM OUTPUT POWER vs. PVDD (WITH THERMAL SHUTDOWN, MONO)
MAX98400 toc34
OUTPUT POWER vs. LOAD (MONO)
MAX98400 toc35
OUTPUT POWER vs. LOAD (MONO)
45 40 35 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 LOAD (I) 1% THD+N 10% THD+N VPVDD = 18V
MAX98400 toc36
100 90 80 MAXIMUM POUT (W) 70 60 50 40 30 20 10 0 8 4I LOAD, THERMAL FOLD DISABLED 12 16 20 24 1% THD+N 10% THD+N
25 20 15 10 5 1% THD+N 0 0 10% THD+N
VPVDD = 12V
50
POUT (W)
28
10 20 30 40 50 60 70 80 90 100 LOAD (I)
PVDD SUPPLY VOLTAGE (V)
10
POUT (W)
Stereo, High-Power, Class D Amplifiers
Typical Operating Characteristics (continued)
(MAX98400A, VPVDD = 18V, VSHDN = 5V, LIM_TH = VS, TEMPLOCK = unconnected; G1 = GND, G2 = open (gain = 20.1dB), CIN = CREL = C1 = C2 = 1FF, typical values are at TA = +25NC, unless otherwise noted.)
OUTPUT POWER vs. LOAD (MONO)
MAX98400 toc37
MAX98400A/MAX98400B
SUPPLY CURRENT vs. PVDD SUPPLY VOLTAGE (MONO)
12 SUPPLY CURRENT (mA) 10 8 6 4 2 IVS
MAX98400 toc38
80 70 60 POUT (W) 50 40 30 20 10 0 0 1% THD+N 10% THD+N
VPVDD = 24V
14 IPVDD
VS = 5V 0 8 12 16 20 24 28 PVDD SUPPLY VOLTAGE (V)
10 20 30 40 50 60 70 80 90 100 LOAD (I)
SUPPLY CURRENT vs. VS SUPPLY VOLTAGE (MONO)
MAX98400 toc39
MAXIMUM OUTPUT POWER vs. PVDD (NO THERMAL SHUTDOWN, MONO)
MAX98400 toc40
14
12 SUPPLY CURRENT (mA) 10 8 6 4 2 VPVDD = 18V 0 4.75 5.00 5.25 IVS IPVDD
60 50 MAXIMUM POUT (W) 40 30 20 10 4I LOAD, THERMAL FOLD DISABLED 0 8 12 16 20 24
5.50
28
VS SUPPLY VOLTAGE (V)
PVDD SUPPLY VOLTAGE (V)
LIMITER TRANSFER CHARACTERISTIC
22 20 OUTPUT VOLTAGE (V) 18 16 14 12 10 8 6 4 2 0 0 0.5 1.0 1.5 VPVDD = 8V RL = 8I + 68H LIM_TH = GND VPVDD = 24V VPVDD = 18V
MAX98400 toc41
LIMITER RELEASE TIME
MAX98400 toc42
24
LIM_TH = GND INPUT 2V/div
OUTPUT 4V/div tRELEASE
2.0
2.5
3.0
200ms/div
INPUT VOLTAGE (V)
11
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Pin Configurations
TOP VIEW TEMPLOCK RELEASE
OUTR+
OUTR+
OUTR-
OUTR-
SHDN
27 26 25 24 23 22 21 20 19
N.C. PGND PGND PVDD PVDD PVDD PGND PGND N.C.
28 29 30 31 32 33 34 35 36
18 17 16 15 14 13 12 11 10 9
N.C. INR+ INRGND GND MONO INLINL+ LIM_TH PGND 19 PGND 20 PVDD 21 PVDD 22 PGND 23 PGND 24
18
17
16
15
RELEASE 14
OUTR+
OUTR-
OUTR-
SHDN
TOP VIEW
13 12 INR+ 11 INR-
MAX98400A
TEMPLOCK 10 GND 9 8 EP INLINL+ LIM_TH 7 6 G2
N.C.
N.C.
MAX98400B
+
1 2 3 4 5 6 7
EP
8
+
1 OUTL2 OUTL3 OUTL+ 4 VS 5 G1
OUTL+
OUTL-
OUTL-
N.C.
OUTL+
N.C.
G1
G2
VS
TQFN
TQFN
Pin Descriptions
PIN MAX98400A 1, 2 3, 7, 18, 22, 25, 28, 36 4, 5 6 8 9 MAX98400B 1, 2 -- 3 4 5 6 NAME OUTLN.C. OUTL+ VS G1 G2 Negative Left Speaker Output No Connection Positive Left Speaker Output 5V Regulator Supply. Bypass VS to GND with a 1F capacitor. Connect to a +5V source for dual-supply operation. Three-State Input for Gain Selection 1. See the Detailed Description section. Three-State Input for Gain Selection 2. See the Detailed Description section. See the Limiter Threshold Control (LIM_TH) section for details. Connect to: 1) VS to disable limiter. 2) GND to have no clipping. 3) RLIM1 resistor to GND to have a PVDD tracking threshold. 4) RLIM1 and RLIM2 resistor-divider to have an absolute threshold. FUNCTION
10
7
LIM_TH
12
Stereo, High-Power, Class D Amplifiers
Pin Descriptions (continued)
PIN MAX98400A MAX98400B 11 12 13 14, 15 16 17 8 9 -- 10 11 12 NAME INL+ INLMONO GND INRINR+ FUNCTION Left-Channel Positive Analog Input Left-Channel Negative Analog Input Mono Operation. Connect MONO to GND for stereo operation. Connect MONO to VS for mono operation. Analog Ground Right-Channel Negative Analog Input Right-Channel Positive Analog Input See the Thermal Foldback section for details. Connect to: 1) GND to disable thermal foldback. 2) Leave open to enable thermal foldback. Sets the Limiter Time Constant. Connect to GND through 1FF. Active-Low Shutdown Input Low = shutdown High = enable Positive Right Speaker Output Negative Right Speaker Output Power Ground Power Supply. Bypass PVDD to PGND with 1FF and 200FF capacitors. Exposed Pad. Connect to PGND for optimum thermal performance.
MAX98400A/MAX98400B
19
13
TEMPLOCK
20 21 23, 24 26, 27 29, 30, 34, 35 31, 32, 33 --
14 15 16 17, 18 19, 20, 23, 24 21, 22 --
RELEASE SHDN OUTR+ OUTRPGND PVDD EP
13
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Stereo Configuration for MAX98400A
8V TO 28V C2 1.0F VS 6 MONO CIN 1.0F 13 REGULATOR INL+ 11 CLIPPING LIMITER 4, 5 OUTL+ PGA 1, 2 OUTLTEMPLOCK 19 CIN 1.0F THERMAL FOLDBACK POWER STAGE C1 1.0F PVDD 31, 32, 33 CBULK 200F
MAX98400A
LEFT INPUT
CIN 1.0F
INL- 12
23, 24 OUTR+
INR+ 17 CLIPPING LIMITER PGA WITH THERMAL AND OVERCURRENT PROTECTION 26, 27 OUTR-
RIGHT INPUT
CIN 1.0F
INR- 16
LIMITER CONTROL
GAIN SELECTION
BIAS AND OSCILLATOR 29, 30, 34, 35 PGND
10 LIM_TH
20 RELEASE CREL 1.0F
8 G1
9 G2
21 SHDN
14, 15 GND
ENABLE
14
Stereo, High-Power, Class D Amplifiers
Mono Configuration for MAX98400A
8V TO 28V
MAX98400A/MAX98400B
C2 1.0F VS VS MONO CIN 1F LEFT INPUT CIN 1F CIN 1F RIGHT INPUT CIN 1F 6
C1 1.0F PVDD
CBULK 200F
31, 32, 33 REGULATOR
13
MAX98400A
4, 5 OUTL+ PGA 1, 2 OUTL-
INL+ 11 CLIPPING LIMITER
INL- 12
TEMPLOCK
19
THERMAL FOLDBACK
POWER STAGE
23, 24 OUTR+
INR+ 17 CLIPPING LIMITER PGA WITH THERMAL AND OVERCURRENT PROTECTION 26, 27 OUTR-
INR- 16
LIMITER CONTROL
GAIN SELECTION
BIAS AND OSCILLATOR 29, 30, 34, 35 PGND
10 LIM_TH
20 RELEASE CREL 1.0F
8 G1
9 G2
21 SHDN
14, 15 GND
ENABLE
Detailed Description
The MAX98400A/MAX98400B Class D amplifiers provide high-performance, thermally efficient amplifier solutions. The MAX98400A delivers 2x20W into 8I loads or 1x40W into a 4I load. The MAX98400B delivers 2x12W into 8I loads. An integrated limiting circuit prevents output clipping distortion and protects small speakers from transient voltages. A thermal-foldback feature can be enabled to automatically reduce the output power if the supply voltage, input signal, and/or ambient temperature are too high to operate within a junction temperature of +130NC. Traditional
thermal protection is also available in addition to robust overcurrent protection. Both devices operate from an 8V to 28V supply and provide a high 67dB PSRR, eliminating the need for a regulated power supply. They offers up to 90% efficiency from a 12V supply. Filterless modulation allows the ICs to pass EN55022B EMI limits with 1m cables using only a low-cost ferrite bead and small-value capacitor on each output (Figure 1). Comprehensive click-and-pop reduction circuitry minimizes noise coming into and out of shutdown.
15
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
The MAX98400A/MAX98400B are available in 36-pin and 24-pin TQFN packages, respectively, and are specified over the -40NC to +85NC temperature range. The high efficiency of a Class D amplifier is due to the switching operation of the output stage transistors. In a Class D amplifier, the output transistors act as switches and consume negligible power. Power loss associated with the Class D output stage is due to the I2R loss of the MOSFET on-resistance, various switching losses, and quiescent current overhead. The theoretical best efficiency of a linear amplifier is 78% at peak output power. Under typical music reproduction levels, the efficiency falls below 30%, whereas these ICs exhibit > 85% efficiency under the same conditions (Figure 2). The ICs feature a shutdown mode that reduces power consumption and extends battery life in portable applications. The shutdown mode reduces supply current to 8FA (typ). Drive SHDN high for normal operation. Drive SHDN low to place the device in low-power shutdown mode. In shutdown mode, the outputs are high impedance and the common-mode voltage at the output decays to zero. The shutdown mode serves as a mute function. The ICs feature comprehensive click-and-pop suppression that minimizes audible transients on startup and shutdown. While in shutdown, the H-bridge is in a highimpedance state. The MAX98400A features a mono mode that allows the right and left channels to operate in parallel, achieving up to 40W of output power. Apply a logic-high (VS) to MONO to enable mono mode. In mono mode, an audio signal applied to the left channel (INL) is routed to the H-bridges of both channels. Connect OUTL+ to OUTR+ and OUTL- to OUTR- using heavy PCB traces as close as possible to the device. Driving MONO low (stereo mode) while the outputs are wired together in mono mode can trigger the short-circuit or thermal-overload protection, or both. The ICs feature a programmable clipping limiter to prevent output clipping distortion and excessive power dissipation and to protect small speakers. All limiter functionality is controlled by two pins: LIM_TH and RELEASE. The voltage applied at the LIM_TH pin controls the threshold when the limiter acts, and the capacitor at the RELEASE pin controls the release time of the limiter. The limiter controls both left and right channels together.
Click-and-Pop Suppression
Efficiency
Mono Configuration
Shutdown
Clipping Limiter
40 30 AMPLITUDE (dBV/m) 20 10 0 -10 30 100 FREQUENCY (MHz) 1000 EFFICIENCY (%)
EFFICIENCY vs. OUTPUT POWER
100 90 80 70 60 50 40 30 20 10 0 0 5 10 15 20 TOTAL OUTPUT POWER (W)
MAX98400A
CLASS AB
Figure 1. MAX98400B EMI Performance
Figure 2. MAX98400A Efficiency vs. Class AB Efficiency
16
Stereo, High-Power, Class D Amplifiers
Limiter Threshold Control (LIM_TH) There are three modes for the limiter, defined by VLIM_TH, the voltage applied to the LIM_TH pin (Table 1). In Mode1, the limiter is disabled. The output clips when output peak voltage reaches the voltage on PVDD, VPVDD. In Mode2, the limiter threshold (VTHRESH) tracks supply voltage, VPVDD. The peak output voltage is limited to approximately VTHRESH = VPVDD x 0.95. In Mode3, the limiter threshold, VTHRESH, is programmable. VLIM_TH can be set to a voltage proportional to the desired output threshold. The limiter threshold can be set down to 0.5 x VPVDD and up to 1.6 x VPVDD. VTHRESH cannot exceed 22V. Threshold settings below VPVDD can be used to protect speakers; the peak output voltage is limited to a value of VTHRESH = VLIM_TH x 6.4. Threshold settings above VPVDD can be used to limit the output distortion; the peak output voltage is limited to a value of VTHRESH = VLIM_TH x 6.4 x 0.95. The 0.95 factor takes into account the voltage drop across the power FET that occurs when the amplifier is clipped. Choose RLIM1 and RLIM2 (Figure 3) to set the desired voltage at the LIM_TH pin. For best accuracy, the parallel combination RLIM1||RLIM2 should be approximately 100kI. Example: If the speaker in the application can handle only 12V peak, but VPVDD is higher, the threshold voltage (VTHRESH) should be set to 12V: VTHRESH = 12V The voltage that needs to be applied to VLIM_TH is then defined as: VLIM_TH = VTHRESH/6.4 = 12V/6.4 = 1.88V
Figure 3. Limiter Control, Mode3 Configuration (Table 1)
For a 5V supply, a resistor-divider of RLIM1 = 165kI/ RLIM2 = 270kI gives both an unloaded voltage of 1.82V and the desired output resistance of approximately 100kI. If only distortion limiting is desired, set VTHRESH to be 20% higher than VPVDD. This limits the output clipping levels to approximately 10% THD. The attack time for the limiter is fixed, typically < 200Fs. Release Time Control (RELEASE) The release time for the limiter is set by an external capacitor at RELEASE (CREL) to GND. Choose CREL = Release Time [s] x 1FF. The CREL limit is 2.2FF.
MAX98400A/MAX98400B
MAX98400A MAX98400B
PVDD PVDD PVDD 18V C1 1.0F
VS REGULATOR VS C2 1.0F LIMITER CONTROL LIM_TH RELEASE CREL 1.0F
RLIM2
RLIM1
Table 1. Limiter Control Modes
MODE Mode1 NAME Disable FUNCTION The limiter is disabled when connecting LIM_TH to VS or a voltage greater than 3.9V. The output peak voltage is limited to just below the supply voltage, VPVDD. VTHRESH = VPVDD x 0.95 when LIM_TH is connected to ground or a voltage below 0.3V. The output peak voltage, VTHRESH, is limited to the threshold set by the voltage applied on the LIM_TH so that VTHRESH = VLIM_TH x 6.4. When VTHRESH is set 20% higher than VPVDD, the output THD distortion is limited to 10%. LIM_Th VOLTAGE RANGE 3.9V < VLIM_TH P VS VGND P VLIM_TH < 0.15V
Mode2
PVDD tracking
Mode3
Programmable
0.6V P VLIM_TH P 3.8V
Note: VTHRESH is the output peak limiting voltage (limiter threshold voltage). 17
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
The ICs offer eight pin-selectable gain settings, selectable through the G1 and G2 pins. The ICs feature overcurrent protection and two types of thermal protection: thermal foldback and overtemperature protection.
Preamplifier Gain Setting
sequence. The shutdown and recovering sequence is repeated until the output fault is removed.
Protection
Applications Information
Traditional Class D amplifiers require an output filter to recover the audio signal from the amplifier's output. The filters add cost, increase the solution size of the amplifier, and can decrease efficiency and THD+N performance. The traditional PWM scheme uses large differential output swings (2 x VDD peak-to-peak) and causes large ripple currents. Any parasitic resistance in the filter components results in a loss of power, lowering the efficiency. These ICs do not require an output filter. The devices rely on the inherent inductance of the speaker coil and the natural filtering of both the speaker and the human ear to recover the audio component of the square-wave output. Eliminating the output filter results in a smaller, lower cost solution. Because the frequency of the ICs' output is well beyond the bandwidth of most speakers, voice coil movement due to the square-wave frequency is very small. For optimum results, use a speaker with a series inductance > 10FH. Typical 8I speakers exhibit series inductances in the 20FH to 100FH range.
Filterless Class D Operation
Thermal Foldback The ICs feature thermal foldback that helps prevent unwanted thermal-shutdown events. If activated, thermal foldback attenuates the stereo output signal once the internal junction temperature exceeds +130NC. Attenuation is applied proportionally as the junction temperature (TJ) exceeds the fixed +130NC threshold. The thermal-foldback mode is controlled by the TEMPLOCK pin. Overtemperature Protection The ICs feature an overtemperature protection that disables the amplifier if the junction temperature exceeds +165NC. Once the amplifier is disabled and the die temperature has cooled by 20NC, the devices enable again and resume normal operation. Overcurrent Protection When the output current reaches the current limit, 5A (typ), the ICs disable the outputs and initiate a recovering
Table 2. Gain Selection
G1 GND Unconnected VS GND Unconnected VS GND Unconnected VS G2 GND GND GND Unconnected Unconnected Unconnected VS VS VS GAIN SETTING (dB) 9 13 16.7 20.1 23.3 26.4 29.8 32.9 Reserved
18
Stereo, High-Power, Class D Amplifiers
Some applications use the ICs with a full inductor-/ capacitor-based (L/C) output filter. See Figure 4 for the correct connections of these components. The load impedance of the speaker determines the filter component selection (Table 3). Inductors L1 and L2 and capacitor C1 form the primary output filter. Capacitors C2 and C3 provide commonmode filtering to reduce radiated emissions. Capacitors C4 and C5, plus resistors R1 and R2, form a Zobel at the output. A Zobel corrects the output loading to compensate for the rising impedance of the loudspeaker. Without a Zobel, the filter exhibits a peak response near the cutoff frequency.
Inductor-Based Output Filters
Internal Regulator VS For highest efficiency operation and best thermal performance, especially at higher VPVDD levels, the VS can be supplied from an external 5V supply. To do this, connect a 5V source to the VS pin (4.75V to 5.5V). When a 5V supply is connected to the VS pin, the internal regulator is automatically disabled and the power dissipation of the ICs is reduced. Proper layout and grounding are essential for optimum performance. Use wide traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. Proper grounding improves audio performance, minimizes crosstalk between channels, and prevents switching noise from coupling into the audio signal. Connect PGND and GND together at a single point on the PCB. Route all traces that carry switching transients away from GND and the traces/ components in the audio signal path. Bypass each PVDD pin with a 0.1FF capacitor to PGND. Place the bypass capacitors as close as possible to the ICs. Place a 220FF capacitor between PVDD and PGND. Bypass both PVDD and VS pins with a 1FF capacitor to GND. Use wide, low-resistance output traces. Current drawn from the outputs increases as load impedance decreases. High-output trace resistance decreases the power delivered to the load. The TQFN package features an exposed thermal pad on its underside. This pad lowers the package's thermal resistance by providing a heat conduction path from the die to the PCB. Connect the exposed thermal pad to PGND by using a large pad and multiple vias to the PGND plane. For best optimum thermal performance, use 2oz copper and allow lots of PCB area around the device.
MAX98400A/MAX98400B
Supply Bypassing, Layout, and Grounding
Component Selection
Input Capacitor The input AC-coupling capacitors allow the amplifier to automatically bias the signal to an optimum DC level. 1FF is recommended for the input capacitor. Power Supplies The ICs are designed to be operated from a singlesupply voltage, VPVDD, which can range from 8V to 28V. Inside the ICs, this VPVDD supplies power for the output FETs and other high-power circuitry, while the low-power circuitry operates from VS, an internally generated 5V supply (4.6V typ). VS is internally generated from a linear regulator that is powered from VPVDD. Bypass both PVDD and VS pins to ground with a 1FF capacitor.
C2 C4 R1 L1 C1
MAX98400A/B
L2
C3
C5 R2
Chip Information
PROCESS: CMOS
Figure 4. Output Filter for PWM Mode
Table 3. Filter Component Selection
RL (I) 4 8 16 L1, L2 (h) 10 15 33 C1 (F) 0.47 0.15 0.10 C2, C3 (F) 0.10 0.15 0.10 C4, C5 (F) 0.22 0.15 0.10 R1, R2 (I) 10 15 33 19
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Functional Diagrams
VS 6 MONO
PVDD 31, 32, 33
13
REGULATOR
MAX98400A
INL+ 11 CLIPPING LIMITER PGA
4, 5 OUTL+
INL- 12
1, 2 OUTLTEMPLOCK 19 THERMAL FOLDBACK POWER STAGE 23, 24 OUTR+ WITH THERMAL AND OVERCURRENT PROTECTION
INR+ 17 CLIPPING LIMITER PGA
26, 27 OUTR-
INR- 16
LIMITER CONTROL
GAIN SELECTION
BIAS AND OSCILLATOR 29, 30, 34, 35 PGND
10 LIM_TH
20 RELEASE
8 G1
9 G2
21 SHDN
14, 15 GND
20
Stereo, High-Power, Class D Amplifiers
Functional Diagrams (continued)
MAX98400A/MAX98400B
VS 4
PVDD 21, 22
REGULATOR
MAX98400B
INL+ 8 CLIPPING LIMITER PGA
3 OUTL+
INL- 9
1, 2 OUTLTEMPLOCK 13 THERMAL FOLDBACK POWER STAGE 16 OUTR+ WITH THERMAL AND OVERCURRENT PROTECTION
INR+ 12 CLIPPING LIMITER PGA
17, 18 OUTR-
INR- 11
LIMITER CONTROL
GAIN SELECTION
BIAS AND OSCILLATOR 19, 20, 23, 24 PGND
7 LIM_TH
14 RELEASE
5 G1
6 G2
15 SHDN
10 GND
21
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 90-0052 90-0068
36 TQFN-EP 24 TQFN-EP
T3666+2 T2444+4
21-0141 21-0139
22
Stereo, High-Power, Class D Amplifiers
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
MAX98400A/MAX98400B
23
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
24
Stereo, High-Power, Class D Amplifiers
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
MAX98400A/MAX98400B
25
Stereo, High-Power, Class D Amplifiers MAX98400A/MAX98400B
Revision History
REVISION NUMBER 0 REVISION DATE 6/10 Initial release DESCRIPTION PAGES ChANGED --
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
26
(c)
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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