General Description
The MAX98307/MAX98308 fully differential mono Class
DG multilevel power amplifiers with integrated inverting
charge pumps offer highly efficient, high-power audio
solutions for portable applications.
Class DG multilevel modulation extends the dynamic
range of the output signal by employing a charge-pump-
generated negative rail as needed to extend the supply
range. This scheme results in high efficiency over a wide
output power range.
The ICs combine Maxim’s active emissions limiting edge
rate and overshoot control circuitry with multilevel output
modulation to greatly reduce EMI. These features elimi-
nate the need for output filtering as compared to tradition-
al Class D devices, reducing component count and cost.
The MAX98307’s 16-pin TQFN package features an
adjustable gain set by external resistors. The MAX98308’s
space-saving 12-bump WLP package features an inter-
nally fixed gain of 8.5dB, 11.5dB, 14.5dB, 17.5dB, and
20.5dB set by a single gain input. Both devices operate
over the extended -40°C to +85°C temperature range.
Applications
Benets and Features
●High Efficiency Combined with High Output Power
• Class DG Multilevel Modulation Ensures Maximum
Efciency Over Wide Output Power Range
●Improves Battery Life
• Low 1.85mA Quiescent Current
●High Output Power at 1% THD+N
• 1.54W at VPVDD = 3.6V, 8Ω + 68μH Load
• 2.85W at VPVDD = 5V, 8Ω + 68μH Load
●High Output Power at 10% THD+N
• 1.77W at VPVDD = 3.6V, 8Ω + 68μH Load
• 3.3W at VPVDD = 5V, 8Ω + 68μH Load
●84% Efficiency (VPVDD = 3.6V, at 500mW Output)
●Active Emissions Limiting and Class DG Multilevel
Output Modulation Eliminates EMI Output Filtering
Requirement
● Integrated Charge Pump and High Efficiency Results
in Small Solution Size
● Excellent RF Immunity
●Click-and-Pop Suppression
●Thermal and Overcurrent Protection
●Low-Current Shutdown Mode
Ordering Information appears at end of data sheet.
19-5848; Rev 6; 6/16
●Cellular Phones
●Smartphones
●Notebook Computers
●VoIP Phones
●Portable Audio
●Tablet PCs
PVDD
GND
FB-
FB+
IN-
IN+
SHDN PVSS
PGND
SVSS
C1P
C1N
OUT+
OUT-
VCC
CHARGE PUMP
CLASS DG
AMPLIFIER
MAX98307
PVDD
GND
IN-
IN+
SHDN PVSS
PGND
C1P
C1N
OUT+
OUT-
GAIN
CHARGE PUMP
CLASS DG
AMPLIFIER
MAX98308
Simplied Block Diagrams
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplifier
EVALUATION KIT AVAILABLE
PVDD
GND
FB-
FB+
20kΩ
20kΩ
10kΩ
0.33µF
0.33µF 10kΩ
12
1 713 3 14
16
15
4
5
8
62
11
10
9
*SYSTEM BULK CAPACITOR
IN-
IN+
SHDN SVSS PVSS
PGND
C1P
C1N
OUT+
OUT-
N.C.
VCC
10µF* 10µF
4.7µF
0.1µF
2.6V TO 5.25
CHARGE PUMP
CLASS DG
AMPLIFIER
MAX98307
0.1µF
PVDD
GND
GAIN B3
0.33µF
0.33µF
B2 A3 C1
A1
B1
A4
B4
C4A2
C3
C2
*SYSTEM BULK CAPACITOR
IN-
IN+
SHDN PVSS
PGND
C1P
C1N
OUT+
OUT-
10µF* 10µF
4.7µF
0.1µF
2.6V TO 5.25
CHARGE PUMP
CLASS DG
AMPLIFIER
MAX98308
MAX98307 Typical Application Circuit
MAX98308 Typical Application Circuit
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
2
PVDD to GND .........................................................-0.3V to +6V
PGND to GND ......................................................-0.3V to +0.3V
C1N to GND ......................................... (VPVSS - 0.3V) to +0.3V
IN+, IN- (MAX98307) ................................ -0.3V to (VCC + 0.3V)
VCC to PVDD (MAX98307) ..................................-0.3V to +0.3V
PVSS to SVSS (MAX97307) ................................ -0.3V to +0.3V
PVSS, SVSS to GND (MAX98307) ......................... -6V to +0.3V
IN+, IN- (MAX98308) ............................................... -0.3V to +6V
PVSS to GND (MAX98308) ....................................-6V to +0.3V
All Other Pins to GND ..........................-0.3V to (VPVDD + 0.3V)
Continuous Current Into/Out of PVDD, VCC, PGND, GND,
OUT+, OUT-, C1P, C1N, PVSS, SVSS ...................... ±800mA
Continuous Current (all other pins) ..................................±20mA
Duration of OUT+/OUT- Short Circuit to PGND
or PVDD ................................................................Continuous
Short-Circuit Duration Between
OUT+ and OUT- Pins ............................................Continuous
Continuous Power Dissipation (TA = +70°C) for Multilayer Board
TQFN (derate 20.8mW/°C above +70°C)..................1667mW
WLP (derate 13.7mW/°C above +70°C) ....................1100mW
Junction Temperature ...................................................... +150°C
Operating Temperature Range ........................... -40°C to +85°C
Storage Temperature Range ............................ -65°C to +150°C
Lead Temperature (soldering, 10s) (TQFN-EP) .............. +300°C
Soldering Temperature (reflow) ....................................... +260°C
TQFN
Junction-to-Ambient Thermal Resistance (θJA) ..........48°C/W
Junction-to-Case Thermal Resistance (θJC) ...............10°C/W
WLP
Junction-to-Ambient Thermal Resistance (θJA) ..........73°C/W
Junction-to-Case Thermal Resistance (θJC) ...............30°C/W
(Note 1)
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-. [MAX98307 RIN+ = RIN- = 10kΩ,
RFB+ = RFB- = 20kΩ] CIN+ = CIN- = 0.33µF, AV = 14.5dB, AC measurement bandwidth 20Hz to 20kHz, TA = TMIN to TMAX, unless
otherwise noted. Typical values are at TA = +25°C.) (Notes 2, 3)
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Absolute Maximum Ratings
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.
Package Thermal Characteristics
Electrical Characteristics
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Range VPVDD, VCC Guaranteed by PSRR test 2.6 5.25 V
Quiescent Current IDD VPVDD = 3.6V 1.85 2.7 mA
Shutdown Current ISHDN SHDN = GND 0.225 10 µA
Power-Supply Rejection Ratio
(Note 4) PSRR
VPVDD = 2.6V to 5.25V 78
dBf = 217Hz, 200mVP-P ripple 78
f = 10kHz, 200mVP-P ripple 67
Turn-On Time tON
Time from shutdown
or power-on to full
operation
MAX98308 25 40
ms
MAX98307,
RIN = 10kΩ 50 80
Input DC Bias Voltage VBIAS 1.3 V
Input Resistance (MAX98308) RIN
AV = 20.5dB (maximum gain) 15 22
kΩ
AV = 17.5dB 22
AV = 14.5dB 22
AV = 11.5dB 28
AV = 8.5dB 40
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
3
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-. [MAX98307 RIN+ = RIN- = 10kΩ,
RFB+ = RFB- = 20kΩ] CIN+ = CIN- = 0.33µF, AV = 14.5dB, AC measurement bandwidth 20Hz to 20kHz, TA = TMIN to TMAX, unless
otherwise noted. Typical values are at TA = +25°C.) (Notes 2, 3)
Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Voltage Gain
(MAX98308) AV
GAIN = short to GND 20 20.5 21
dB
GAIN = 100kΩ pulldown to GND 17 17.5 18
GAIN = short to PVDD 14 14.5 15
GAIN = 100kΩ pullup to PVDD 11 11.5 12
GAIN = unconnected 8 8.5 9
Common-Mode Rejection Ratio
(MAX98308) CMRR fIN = 1kHz 65 dB
Output Power (MAX98307) POUT
fIN = 1kHz,
THD+N = 1%
ZL = 8Ω + 68µH,
VPVDD = 3.6V 1.54
W
ZL = 8Ω + 68µH,
VPVDD = 4.2V 2
ZL = 8Ω + 68µH,
VPVDD = 5.0V 2.85
fIN = 1kHz,
THD+N = 10%
ZL = 8Ω + 68µH,
VPVDD = 3.6V 1.77
ZL = 8Ω + 68µH,
VPVDD = 4.2V 2.3
ZL = 8Ω + 68µH,
VPVDD = 5.0V 3.3
Output Power (MAX98308) POUT
THD+N ≤ 1%
ZSPK = 8Ω + 68µH,
VPVDD = 3.6V 1.4
W
ZSPK = 8Ω + 68µH,
VPVDD = 4.2V 1.92
ZSPK = 8Ω + 68µH,
VPVDD = 5.0V 2.7
THD+N ≤ 10%
ZSPK = 8Ω + 68µH,
VPVDD = 3.6V 1.57
ZSPK = 8Ω + 68µH,
VPVDD = 4.2V 2.13
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
4
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-. [MAX98307 RIN+ = RIN- = 10kΩ,
RFB+ = RFB- = 20kΩ] CIN+ = CIN- = 0.33µF, AV = 14.5dB, AC measurement bandwidth 20Hz to 20kHz, TA = TMIN to TMAX, unless
otherwise noted. Typical values are at TA = +25°C.) (Notes 2, 3)
Note 2: 100% production tested at TA = +25°C. Specifications over temperature limits are guaranteed by design.
Note 3: Testing performed with a resistive load in series with an inductor to simulate an actual speaker. For RL = 8Ω, L = 68µH.
Note 4: Amplifier inputs AC-coupled to GND.
Note 5: Specified at room temperature with an 8Ω resistive load in series with a 68µH inductive load connected across the BTL
outputs. Mode transitions controlled by SHDN active-low shutdown control.
Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Total Harmonic Distortion Plus
Noise THD+N fIN = 1kHz, POUT = 1W 0.05 %
Output Offset Voltage VOS TA = +25°C ±1 ±5 mV
Click-and-Pop Level KCP
Peak voltage,
A-weighted,
32 samples per
second (Notes 4, 5)
Into shutdown -65
dBV
Out of shutdown -65
Output Switching Frequency 340 kHz
Efficiency η
fIN = 1kHz, POUT at 500mW,
THD+N = 0.02% 84 %
fIN = 1kHz, POUT at 1W, THD+N = 0.05% 82
Current Limit ILIM 2 ARMS
Output Noise VNA-weighted 52 µVRMS
LOGIC INPUT (SHDN)
Input Voltage High VIH 1.4 V
Input Voltage Low VIL 0.4 V
Input Leakage Current TA = +25°C ±10 µA
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
5
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98307)
MAX98307 toc01
OUTPUT POWER (W)
2.0
1.51.00.50 2.5
THD+N (%)
0.01
0.1
1
10
100
0.001
VPVDD = 3.6V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98308)
MAX98307 toc04
OUTPUT POWER (W)
2.0
1.51.00.50 2.5
THD+N (%)
0.01
0.1
1
10
100
0.001
VPVDD = 3.6V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98307)
MAX98307 toc02
OUTPUT POWER (W)
3.0
2.52.01.51.00.50 3.5
THD+N (%)
0.01
0.1
10
100
0.001
1
VPVDD = 4.2V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
MAX98307 toc05
2.52.01.51.00.50 3.0
THD+N (%)
0.01
0.1
10
100
0.001
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98308)
VPVDD = 4.2V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98307)
MAX98307 toc03
OUTPUT POWER (W)
4
3210 5
THD+N (%)
0.01
0.1
1
10
100
0.001
VPVDD = 5V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
MAX98307 toc06
3.53.02.52.01.51.00.50 4.0
THD+N (%)
0.01
0.1
10
100
0.001
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER (MAX98308)
VPVDD = 5V
fIN = 1kHz
fIN = 100Hz
fIN = 6kHz
OUTPUT POWER (W)
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
6
www.maximintegrated.com
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics (continued)
MAX98307 toc07
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98307)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 3.6V
POUT = 300mW
POUT = 1.3W
MAX98307 toc10
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98308)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 3.6V
POUT = 300mW
POUT = 1.1W
MAX98307 toc08
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98307)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 4.2V
POUT = 500mW
POUT = 1.6W
MAX98307 toc11
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98308)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 4.2V
POUT = 500mW
POUT = 1.6W
MAX98307 toc09
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98307)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 5V
POUT = 700mW
POUT = 2.4W
MAX98307 toc12
0.01
0.1
1
10
0.001
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY (MAX98308)
FREQUENCY (kHz)
THD+N (%)
10k1k100 100k
VPVDD = 5V
POUT = 700mW
POUT = 2.4W
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
7
www.maximintegrated.com
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics (continued)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98307)
MAX98307 toc13
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
10010
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0
1 1k
VPVDD = 3.6V
fIN = 1kHz
THD+N = 1%
THD+N = 10%
MAX98307 toc16
0.2
0.6
0.8
0
1.0
1.2
1.4
1.6
0
OUTPUT POWER (W)
LOAD RESISTANCE (Ω)
100101 1k
VPVDD = 3.6V
fIN = 1kHz
THD+N = 1%
THD+N = 10%
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98308)
OUTPUT POWER (W)
0.5
1.0
1.5
2.0
2.5
0
MAX98307 toc14
LOAD RESISTANCE (Ω)
100101 1k
VPVDD = 4.2V
fIN = 1kHz
THD+N = 1%
THD+N = 10%
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98307)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98308)
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
10010
0.5
1.0
1.5
2.0
2.5
0
1 1k
THD+N = 10%
THD+N = 1%
MAX98307 toc17
VPVDD = 4.2V
fIN = 1kHz
MAX98307 toc15
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
OUTPUT POWER (W)
LOAD RESISTANCE (Ω)
100101 1k
VPVDD = 5V
fIN = 1kHz
THD+N = 1%
THD+N = 10%
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98307)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX98308)
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
100101 1k
THD+N = 10%
THD+N = 1%
MAX98307 toc18
VPVDD = 5V
fIN = 1kHz
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
8
www.maximintegrated.com
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics (continued)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX98307)
MAX98307 toc19
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
5.04.63.0 3.4 3.8 4.2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
2.6 5.4
THD+N = 10%
THD+N = 1%
fIN = 1kHz
EFFICIENCY vs. OUTPUT POWER
(MAX98307)
MAX98307 toc22
OUTPUT POWER (W)
EFFICIENCY (%)
1.00.80.60.40.2
10
20
30
40
50
60
70
80
90
0
0 1.2
VPVDD = 3.6V
fIN = 1kHz
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX98308)
MAX98307 toc20
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
5.04.64.23.83.43.0
0.5
1.0
1.5
2.0
3.0
2.5
3.5
0
2.6 5.4
fIN = 1kHz
THD+N = 1%
THD+N = 10%
THERMALLY LIMITED
EFFICIENCY vs. OUTPUT POWER
(MAX98307)
MAX98307 toc23
OUTPUT POWER (W)
EFFICIENCY (%)
10
20
30
40
50
60
70
80
90
0
VPVDD = 4.2V
fIN = 1kHz
1.41.20.8 1.00.4 0.60.20 1.6
GAIN vs. FREQUENCY
(MAX98308)
MAX98307 toc21
FREQUENCY (kHz)
AMPLITUDE (dB)
10k1k100
-10
0
10
20
30
-20
10 100k
GAIN = UNCONNECTED
GAIN = 100kΩ TO VPVDD
GAIN = PGND GAIN = VPVDD
GAIN = 100kΩ TO PGND
EFFICIENCY vs. OUTPUT POWER
(MAX98307)
MAX98307 toc24
OUTPUT POWER (W)
EFFICIENCY (%)
10
20
30
40
50
60
70
80
90
0
VPVDD = 5V
fIN = 1kHz
2.01.51.00.50 2.5
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
9
www.maximintegrated.com
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics (continued)
EFFICIENCY vs. OUTPUT POWER
(MAX98308)
MAX98307 toc25
OUTPUT POWER (W)
EFFICIENCY (%)
1.00.80.60.40.2
10
20
30
40
50
60
70
80
90
0
0 1.2
VPVDD = 3.6V
fIN = 1kHz
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX98307 toc28
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
2.5
3.0
0
2.5 5.5
VPVDD = 3.6V
fIN = 1kHz
EFFICIENCY vs. OUTPUT POWER
(MAX98308)
MAX98307 toc26
OUTPUT POWER (W)
EFFICIENCY (%)
10
20
30
40
50
60
70
80
90
0
VPVDD = 4.2V
fIN = 1kHz
1.41.20.8 1.00.4 0.60.20 1.6
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX98307 toc29
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (nA)
5.04.53.0 3.5 4.0
50
100
150
200
250
300
350
400
0
2.5 5.5
EFFICIENCY vs. OUTPUT POWER
(MAX98308)
MAX98307 toc27
OUTPUT POWER (W)
EFFICIENCY (%)
10
20
30
40
50
60
70
80
90
0
VPVDD = 5V
fIN = 1kHz
2.01.51.00.50 2.5
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
MAX98307 toc30
FREQUENCY (Hz)
PSRR (dB)
10k1k100
-80
-70
-60
-50
-40
-30
-20
-10
0
-90
10 100k
VRIPPLE = 200mVP-P
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
10
www.maximintegrated.com
(VPVDD = VCC = VSHDN = 3.6V, VPGND = VGND = 0V, ZL = 8Ω + 68µH between OUT+ and OUT-, AV = 14.5dB (MAX98307 RIN+ =
RIN- = 10kΩ, RFB+ = RFB- = 20kΩ), CIN+ = CIN- = 0.33μF, AC measurement bandwidth 20Hz to 20kHz.)
Typical Operating Characteristics (continued)
STARTUP RESPONSE
MAX98307 toc33
ISPEAKER
100mA /div
20ms/div
VSHDN
2V/div
SHUTDOWN RESPONSE
MAX98307 toc34
ISPEAKER
100mA /div
20ms/div
VSHDN
2V/div
COMMON-MODE REJECTION
RATIO vs. FREQUENCY (MAX98307)
MAX98307 toc31
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-80
-70
-60
-50
-40
-30
-20
-10
0
-90
10 100k
fIN = 1kHz
COMMON-MODE REJECTION
RATIO vs. FREQUENCY (MAX98308)
MAX98307 toc32
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-70
-60
-50
-40
-30
-20
-10
0
-80
10 100k
WIDEBAND vs. FREQUENCY
MAX98307 toc35
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dBV)
10G1G
-160
-140
-120
-100
-80
-60
-40
-20
0
-180
100k 100G
VPVDD = 3.6V
INBAND OUTPUT SPECTRUM
MAX98307 toc36
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dBV)
10k1k100
-120
-100
-80
-60
-40
-20
0
-140
10 100k
VPVDD = 3.6V CLIPPING WAVEFORM 10% THD+N
MAX98307 toc37
OUT-
1V/div
200µs/div
OUT+
1V/div
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
Maxim Integrated
│
11
www.maximintegrated.com
Pin/Bump Description
Pin/Bump Congurations
15
16
14
13
6
5
7
GND
OUT+
8
IN+
FB-
FB+
1 2
PVSS
4
12 11 9
C1N
C1P EP
N.C.
SVSS
PGND
OUT-
+
PVDD IN-
3
10
VCC
TQFN
MAX98307
TOP VIEW TOP VIEW
(BUMPS SIDE DOWN)
WLP
PGNDPVSS
OUT-C1N
MAX98308
+
1 2 3 4
A
IN+ IN-
GAIN
B
C
SHDN
SHDN
OUT+C1P GND PVDD
PIN BUMP NAME FUNCTION
MAX98307 MAX98308
1 B2 SHDN Active-Low Shutdown. Connect to GND for shutdown. Connect to PVDD for normal
operation.
2 A2 GND Substrate and Signal Ground
3 A3 PVDD Power and Charge-Pump Supply. Bypass to PGND with a 0.1µF capacitor.
4 A4 OUT+ Positive Amplier Output
5 B4 OUT- Negative Amplier Output
6 C4 PGND Power Ground
7 — SVSS Amplier Negative Power Supply. Connect to PVSS (MAX98307).
8 — N.C. No Connection. Not internally connected. Connect to GND or leave unconnected.
9 — FB- Negative Amplier Feedback
10 C3 IN- Negative Amplier Input
11 C2 IN+ Positive Amplier Input
12 — FB+ Positive Amplier Feedback
— B3 GAIN See Table 1 MAX98308 Gain Conguration for more information.
13 — VCC Signal Supply
14 C1 PVSS Charge-Pump Output. Connect a 10µF capacitor between PVSS and PGND.
15 B1 C1N Charge-Pump Flying Capacitor Negative Terminal. Connect a 4.7µF capacitor
between C1N and C1P.
16 A1 C1P Charge-Pump Flying Capacitor Positive Terminal. Connect a 4.7µF capacitor between
C1N and C1P.
— — EP
Exposed Pad (TQFN Only). Internally connected to GND. Connect to a large ground
plane with multiple vias to maximize thermal performance. Not intended as an
electrical connection point.
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
12
Detailed Description
The MAX98307/MAX98308 fully differential mono Class
DG multilevel power amplifiers with integrated inverting
charge pumps offer highly efficient, high-power audio
solutions for portable applications.
The new Class DG multilevel modulation scheme extends
the dynamic range of the output signal by employing a
charge-pump-generated negative rail, which is used as
needed to extend the supply range. When the negative
rail is not needed, the output is drawn entirely from the
standard supply. This scheme results in high efficiency
over a wide output power range.
The power amplifier incorporates active emissions limiting
edge rate and overshoot control circuitry in combination
with the multilevel output modulation scheme to greatly
reduce EMI. These features eliminate the need for output
filtering as compared to traditional Class D amplifiers,
which reduces an application’s component count.
The MAX98307 has an adjustable gain set by external
resistors. The MAX98308 has preset fixed gains of 8.5dB,
11.5dB, 14.5dB, 17.5dB, and 20.5dB set by a gain select
input (GAIN).
Class DG Multilevel Operation
The ICs’ filterless Class DG multilevel amplifiers feature
a proprietary Maxim output stage that offers higher effi-
ciency over a greater output power range than previous
amplifiers. The amplifier combines Class D switching
output efficiency and Class G supply level shifting with a
multilevel output modulation scheme that with a 5V supply
has efficiency better than 80% efficiency over the 0.35W
to 2.2W output range.
The Class DG multilevel output stage uses pulse-width
modulation (PWM), a rail-to-rail digital output signal with
variable duty cycle, to approximate an analog input signal
as in a Class D amplifier. Rail-to-rail operation ensures
that any dissipation at the output is due solely to the
RDS(ON) of the power output MOSFETs. The Class DG
multilevel output stage also senses the magnitude of the
output signal and switches the supply rails as needed
to more efficiently supply the required signal power. For
a low output signal swing requirement (below the bat-
tery supply rail VPVDD), the output range is between
VPVDD and ground. When output swing above VPVDD
is required, VPVSS, an internal inverting charge-pump-
generated negative rail replaces ground as the lower sup-
ply. The high output swing range is then VPVDD to VPVSS,
approximately double the low swing range. This approach
efficiently manages power consumption by switching the
operating rails as needed according to the output swing
requirements. Additionally, multilevel output modulation is
employed in to draw the maximum possible power from
the lower impedance battery supply rail, VPVDD, rather
than the higher impedance charge-pump-generated rail
VPVSS. This is accomplished by generating PWM sig-
nals that swing from ground to VPVDD or from ground to
VPVSS at either end of the bridge tied load (BTL) rather
than continually swinging from VPVDD to VPVSS. The sig-
nals are modulated in such a way that VPVSS is used only
as necessary to generate low-end signal swing.
These combined operations ensure that power dissipation
due to RDS(ON) loss and charge-pump impedance is min-
imized, and that efficiency and output power is maximized
across the audio range. Class DG multilevel operation is
shown as Figure 1.
Figure 1. Class DG Multilevel Operation
MAX98307 fig01
400µs/div
OUT+
5V/div
OUT-
5V/div
OUT+ - OUT-
10V/div
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
13
The Class DG multilevel efficiency compares favor-
ably with Class AB and Class G amplifiers as shown in
Figure 2. Note that efficiency at 1W is 85%.
EMI Filterless Output Stage
Traditional Class D amplifiers require the use of external
LC filters, or shielding, to meet electromagnetic-interfer-
ence (EMI) regulation standards. The active emissions
limiting edge-rate control circuitry and Class DG multilevel
modulation scheme reduce EMI emissions without the
need for external filtering components, while maintaining
high efficiency (see Figure 3).
Amplier Current Limit
If the output current of the speaker amplifier exceeds the
current limit, the ICs disable the outputs for approximately
100µs. After 100µs, the outputs are reenabled. If the fault
condition still exists, the ICs continue to disable and reen-
able the outputs until the fault condition is removed.
Figure 2. Class DG Multilevel vs. Typical Class G and Class
AB Amplifier Efficiency
Figure 3. EMI Performance with VPVDD = 5V, 12in of Speaker Cable, No Output Filter
EFFICIENCY vs. OUTPUT POWER
OUTPUT POWER (W)
EFFICIENCY (%)
1.81.61.2 1.40.4 0.6 0.8 1.00.2
10
20
30
40
50
60
70
80
90
0
0 2.0
MAX98307/MAX98308
CLASS DG MULTILEVEL AMPLIFIER
CLASS AB AMPLIFIER
CLASS G AMPLIFIER
VPVDD = 5V
fIN = 1kHz
1000
-10
10
30
50
70
90
200 300 400 500
EN55022B LIMIT
HORIZONTAL
VERTICAL
600 700 800 900 1000
FREQUENCY (MHz)
EMISSIONS LEVEL (dBµV/m)
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
14
Click-and-Pop Suppression
The speaker amplifier features Maxim’s comprehensive
click-and-pop suppression. During startup, the click-and-
pop suppression circuitry reduces any audible transient
sources internal to the device. When entering shutdown,
the differential speaker outputs quickly and simultane-
ously ramp down to PGND.
Thermal and Short Circuit Protection
The ICs automatically enter thermal shutdown when the
die temperature is greater than +160°C and reactivate at
less than +135°C. Additionally, if the outputs are shorted
to each other or either rail, the amplifier prevents cata-
strophic loss by disabling the outputs.
Shutdown
The ICs feature a low-power shutdown mode, drawing
less than 0.225µA (typ) supply current. Drive SHDN low
to put the IC into the shutdown state.
Applications Information
Filterless Class DG Operation
Traditional Class DG amplifiers require an output filter.
The filter adds cost and size, as well as decreases effi-
ciency and THD+N performance. The ICs’ active emis-
sions limiting and Class DG multilevel output modulation
allow for filterless operation while reducing external com-
ponent count, and thereby, cost.
Because the switching frequency of the ICs is well beyond
the bandwidth of most speakers, voice coil movement due
to the switching frequency is very small. Use a speaker
with a series inductance > 10µH. Typical 8Ω speakers
exhibit series inductances in the 20µH to 100µH range.
Differential Input Amplier
The ICs feature a differential input configuration, making
the device compatible with many codecs and offering
improved noise immunity as compared to single-ended
input amplifiers. In devices such as mobile phones, noisy
digital signals can be picked up by an amplifier’s input
traces. A differential amplifier amplifies the difference of
the two inputs, while signals common to both inputs, such
as switching noise, are rejected. While both ICs feature
differential amplifiers, their voltage gain is set in differing
manners.
The MAX98307 employs external feedback resistors as
shown in Figure 4. Voltage gain of the input amplifier is
set as:
( )
FB
V
IN
R
A 20log dB 8.5 dB
R
= +
where AV is the desired voltage gain in decibels. RIN+
should be equal to RIN-, and RFB+ should be equal to
RFB-.
In differential input configurations, the common-mode
rejection ratio (CMRR) is primarily limited by the external
resistor and capacitor matching. Ideally, to achieve the
highest possible CMRR, the following external compo-
nents should be selected where:
FB FB-
IN IN-
IN IN-
RR
RR
and
CC
+
+
+
=
=
The gain of the MAX98308 is selectable by connecting
the gain-select bump GAIN as described in Table 1.
Figure 4. Setting the Voltage Gain of the MAX98307
CLASS DG
OUTPUT
STAGE
FB+
IN+
IN-
FB-
RFB-
RFB+
RIN+
RIN-
MAX98307
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
15
Component Selection
Power-Supply Input (PVDD)
PVDD powers the speaker amplifier and has a range
of 2.6V to 5.25V. Bypass PVDD with 0.1µF and 10µF
capacitors in parallel to PGND. Apply additional bulk
capacitance at the device if long input traces between
PVDD and the supply are used.
Input Coupling Capacitors
The AC-coupling capacitors (CIN) and input resistors
(RIN) form highpass filters that remove any DC bias from
an input signal. See the MAX98307 Typical Application
Circuit and MAX98308 Typical Application Circuit. CIN
prevents any DC components from the input signal
source appearing at the amplifier outputs. The -3dB point
of the highpass filter, assuming zero source impedance
due to the input signal source, is given by:
3 dB IN IN
1
f2R C
−=π× ×
Choose CIN so that f-3dB is well below the lowest frequen-
cy of interest. Setting f-3dB too high affects the amplifier’s
low-frequency response. Use capacitors with adequately
low voltage coefficient (X5R or X7R recommended) for
best low frequency THD+N performance.
Charge-Pump Capacitor Selection
Use capacitors with an equivalent series resistance (ESR)
less than 50mΩ for optimum performance. Low-ESR
ceramic capacitors minimize the output resistance of the
charge pump. For best performance over the extended
temperature range, select capacitors with an X7R dielec-
tric and a rated voltage of at least 6.3V.
Charge-Pump Flying Capacitor
The value of the charge-pump flying capacitor affects the
load regulation and output resistance of the charge pump.
A charge-pump flying capacitor value that is too small
(less than 1µF) degrades the amplifier’s ability to provide
sufficient current drive. Increasing the value of this flying
capacitor and decreasing the ESR improves load regula-
tion and reduces the charge-pump output impedance,
which improves the output power and efficiency of the
amplifier. A 4.7µF or greater value, low-ESR capacitor is
recommended.
Charge-Pump Hold Capacitor
The charge-pump hold capacitor value and ESR directly
affect the ripple at the charge-pump rail, PVSS. Increasing
the charge-pump hold capacitor value reduces output
ripple. Likewise, decreasing the ESR of this capacitor
reduces both ripple and output resistance. A 10µF or
greater value, low-ESR capacitor is recommended.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Good grounding improves audio perfor-
mance and prevents switching noise from coupling into
the audio signal.
Use wide, low-resistance output traces. As load imped-
ance decreases, the current drawn from the device
increases. At higher current, the resistance of the output
traces decreases the power delivered to the load. For
example, if 2W is delivered from the device output to an
8Ω load through 100mΩ of total speaker trace, 1.97W is
delivered to the speaker. If power is delivered through
10mΩ of total speaker trace, 1.998W is delivered to the
speaker. Wide output, supply, and ground traces also
improve the power dissipation of the device.
The ICs are inherently designed for excellent RF immu-
nity. For best performance, add ground fills around all
signal traces on top or bottom PCB planes.
Note: For both ICs, the Class DG output stage has a fixed gain of 8.5dB. Any gain or attenuation set by the external input stage
resistors adds to or subtracts from this fixed gain.
Table 1. MAX98308 Gain Configuration
GAIN PREAMPLIFIER GAIN (dB) OVERALL GAIN (dB)
Unconnected 0 8.5
100kΩ to VPVDD 3 11.5
Short to VPVDD 6 14.5
100kΩ to PGND 9 17.5
Short to PGND 12 20.5
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
16
Thermal Considerations
Class DG multilevel amplifiers provide much better effi-
ciency and thermal performance than a comparable Class
AB or Class G amplifier. However, the system’s thermal
performance must be considered with realistic expecta-
tions and include consideration of many parameters. This
section examines Class DG multilevel amplifiers using
general examples to illustrate good design practices.
MAX98307 (TQFN) Applications Information
The exposed pad is the primary route of keeping heat
away from the IC. With a bottom-side exposed pad, the
PCB and its copper becomes the primary heatsink for the
Class DG multilevel amplifier. Solder the exposed pad to
a large copper polygon. Add as much copper as possible
from this polygon to any adjacent pin on the amplifier as
well as to any adjacent components, provided these con-
nections are at the same potential. These copper paths
must be as wide as possible. Each of these paths con-
tributes to the overall thermal capabilities of the system.
The copper polygon to which the exposed pad is attached
should have multiple vias to the opposite side of the PCB.
Make this polygon as large as possible within the sys-
tem’s constraints for signal routing.
MAX98308 (WLP) Applications Information
For the latest application details on WLP construction,
dimensions, tape carrier information, PCB techniques,
bump-pad layout, and recommended reflow temperature
profile, as well as the latest information on reliability test-
ing results, refer to Application Note 1891: Wafer-Level
Packaging (WLP) and Its Applications.
Note: All devices operate over the -40°C to +85°C temperature
range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
*EP = Exposed pad.
Ordering Information
PART GAIN SET PIN-PACKAGE
MAX98307ETE+ External 16 TQFN-EP*
MAX98307ETE/V+ External 16 TQFN-EP*
MAX98308EWC+ Internal 12 WLP
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
17
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
16 TQFN-EP T1633+5 21-0136 90-0032
12 WLP W121A1+1 21-0542 Refer to Application Note 1891
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
www.maximintegrated.com Maxim Integrated
│
18
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 6/11 Initial release —
1 8/11 Updated output power conditions in the Electrical Characteristics table 4
2 9/11 Updated Electrical Characteristics table and TOC 20 2, 4, 8
3 9/11 Added EP to the Pin Description section and removed future product
reference for the MAX98308 12, 17
4 3/12 Added RIN typical values for all gains and corrected error on TOCs 1–6 3, 6
5 3/15 Added MAX98307ETE/V+ to Ordering Information 17
6 6/16 Updated package code and outline number in Package Information table 18
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX98307/MAX98308 3.3W Mono Class DG Multilevel Audio Amplier
© 2014 Maxim Integrated Products, Inc.
│
19
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
