19-5189; Rev 0; 5/10
Boosted 2.2W Class D Amplifier
with Automatic Level Control
General Description
The MAX98500 is a high-efficiency, Class D audio ampli-
fier that features an integrated boost converter to deliver
a constant output power over a wide range of battery
supply voltages.
The boost converter operates at 2MHz, requiring only a
small (2.2FH) external inductor and capacitor.
The automatic level control has a battery tracking func-
tion that reduces the output swing as the supply voltage
drops, preventing collapse of battery voltage.
The amplifier has differential inputs and an internal fully
differential design. The MAX98500 also features three
gain settings (6dB, 15.5dB, and 20dB) that are select-
able with a logic input.
The MAX98500 is available in a small, 0.5mm pitch
16-bump WLP package (2.1mm x 2.1mm). It is specified
over the extended -40NC to +85NC temperature range.
S
Boosted Class D Output
S
Integrated Automatic Level Control
S
Output Power
2.2W into 8I, 10% THD+N
1.7W into 8I, 1% THD+N
S
Wide 2.5V to 5.5V Supply Voltage Range
S
Undervoltage Lockout Protection
S
High Total Efficiency of 87%
S
High Step-Up Switching Frequency (2MHz)
S
Active Emission Limiting for Low EMI
Features
MAX98500
Applications
Cell Phones
Smartphones
GPS Devices
Mobile Internet Devices
Active Speaker Accessories
PART
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX98500EWE+
16 WLP
-40NC to +85NC
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Typical Application Circuit appears at end of data sheet.
Simplified Block Diagram
BATTERY
V
BAT
B4
SDBST D4
SDSPK C3
GAIN B2
RKNEE
B3
CONTROL
A3
BOOST CONVERTER
A2
LX
V
CCOUT
MAX98500
A1 PVDD
INP D2
INN D3
B1 SPKP
DIFFERENTIAL
INPUT
C4
AGND
A4
BSTPGND
GAIN
D1, C2
SPKPGND
OUTPUT
STAGE
C1 SPKN
_______________________________________________________________
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.
Boosted 2.2W Class D Amplifier
with Automatic Level Control
MAX98500
ABSOLUTE MAXIMUM RATINGS
V
BAT
to AGND .........................................................-0.3V to +6V
V
CCOUT
to BSTPGND, AGND .................................-0.3V to +6V
PVDD to SPKPGND .................................................-0.3V to +6V
BSTPGND, SPKPGND to AGND ......................... -0.3V to +0.3V
GAIN to AGND ........................................ -0.3V to (V
BAT
+ 0.3V)
SDBST, SDSPK
to AGND ...................................... -0.3V to V
BAT
All Other Pins (excluding LX) to AGND ..................-0.3V to +6V
Current Into/Out of LX, V
CCOUT
, BSTPGND .....................
Q3.9A
Continuous Current Into/Out of SPK_, PVDD,
SPKPGND ..................................................................
Q800mA
Continuous Input Current (all other pins) ........................
Q20mA
Duration of Short Circuit Between V
CCOUT
and BSTPGND...................................................... Continuous
Duration of SPK_ Short Circuit to PVDD or
SPKPGND ..............................................................Continuous
Duration of Short Circuit Between SPKP
and SPKN ..............................................................Continuous
Continuous Power Dissipation, Multilayer Board (T
A
= +70NC)
WLP (derate 20.4mW/NC above +70NC)........................1.33W
θ
JA
(Note 1).................................................................49NC/W
Junction Temperature .....................................................+150NC
Operating Temperature Range .......................... -40NC to +85NC
Storage Temperature Range............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+260NC
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.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
(V
BAT
= 3.6V, R
L
=
J
between SPKP and SPKN, A
V
= +6dB, C
IN
= 1FF, 20Hz to 22kHz AC measurement bandwidth, T
A
= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER
Power-Supply Rejection Ratio
(Note 3)
SYMBOL
PSRR
I
VBAT
Quiescent Current
I
PVDD
Combined Efficiency
Shutdown Current
Turn-On Time
BOOST CONVERTER
Battery Supply Voltage Range
Soft-Start Interval
Undervoltage Lockout
Boost Converter Output Voltage
Output Current Limit
Input Current Limit
nMOS Current Limit
pMOS Turn-Off Current Limit
Switching Frequency
Efficiency
Startup Short-Circuit Time
Thermal Shutdown
LX Leakage Current
V
LX
= 0V or 5.5V,
V
CCOUT
= 5.5V
T
A
= +25NC
-40NC
P
T
A
P
+85NC
-1.0
f
S
E
0.1A
P
I
OUT
P
0.75A
Converter latch off
1.8
V
BAT
t
ON
UVLO
I
MAX
I
LIMIT
I
LX,MAX
V
BAT
falling
V
BAT
R
= 3.6V
Startup, V
CCOUT
= 0V
2.1
5.45
1.5
0.3
3.3
10
2.0
93
50
165
+0.1
0.1
+1.0
2.2
0.5
V
VCCOUT
I
LOAD
= 0mA
2.5
5.6
2.2
5.5
2.3
5.65
5.5
V
ms
V
V
A
A
A
mA
MHz
%
ms
NC
FA
E
I
SHDN
t
ON
CONDITIONS
T
A
= +25NC, V
BAT
= 2.5V to 5.5V
T
A
= +25NC,
SDSPK
=
SDBST
= V
BAT
T
A
= +25NC, V
SDSPK
= 0V,
SDBST
= V
BAT
T
A
= +25NC, PVDD = 5.55V,
SDSPK
=
SDBST
= V
BAT
P
OUT
= 1.7W, f = 1kHz, Z
SPK
= 8I + 68FH
V
SDSPK
= V
SDBST
= 0V, T
A
= +25NC
Time from power-on to full operation
MIN
TYP
95
3.05
0.09
1.7
87
0.04
10
1.5
12
0.15
2.7
%
FA
ms
mA
MAX
UNITS
dB
2
______________________________________________________________________________________
Boosted 2.2W Class D Amplifier
with Automatic Level Control
ELECTRICAL CHARACTERISTICS (continued)
(V
BAT
= 3.6V, R
L
=
J
between SPKP and SPKN, A
V
= +6dB, C
IN
= 1FF, 20Hz to 22kHz AC measurement bandwidth, T
A
= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER
SPEAKER AMPLIFIER
Output Offset Voltage
V
OS
T
A
= +25NC
Peak voltage, T
A
=
+25NC, A-weighted, 32
samples per second,
Z
SPK
= 8I + 68FH,
(Notes 3, 4)
Z
SPK
= 8I + 68FH
Into shutdown
Out of shutdown
THD+N
P
1%
THD+N
P
10%
1
-56
dBV
-56
1.7
2.2
0.05
300
GAIN = AGND
Gain
Output Current Limit
Efficiency
Output Noise
E
P
OUT
= 1.7W, f = 1kHz, Z
SPK
= 8I + 68FH
A-weighted
A
V
= 6dB
(GAIN = AGND)
SDBST
=
SDSPK
=
V
BAT
A
V
= 15.5dB
(GAIN =
unconnected)
A
V
= 20dB
(GAIN = V
BAT
)
Common-Mode Rejection Ratio
Bias Voltage
ALC
Attack Time
Release Time
Maximum Attenuation
Attenuation Resolution
R
KNEE
= 154kI
Knee Voltage
V
KNEE
T
A
= +25NC
R
KNEE
= 40.5kI
R
KNEE
= 13kI
2.19
3.14
3.71
20
1.6
8
0.5
2.3
3.3
3.9
2.42
3.47
4.10
V
Fs/dB
s/dB
dB
dB
CMRR
V
BIAS
V
SDBST
= V
SDSPK
= 0V
f = 1kHz
All gain settings
1.3
36
12
6.5
A
V
GAIN = unconnected
GAIN = V
BAT
5.5
15
19.5
6
15.5
20
2
92
43
54
18
11
110
60
1.4
1.5
dB
V
72
26
16
6.5
16
20.5
A
%
FV
RMS
dB
W
%
kHz
3
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX98500
Click-and-Pop Level
K
CP
Output Power (Note 5)
Total Harmonic Distortion Plus
Noise
Output Switching Frequency
P
OUT
THD+N
f = 1kHz, P
OUT
= 850mW, T
A
= +25NC,
Z
SPK
= 8I + 68FH
Input Resistance
R
IN
kI
_______________________________________________________________________________________
3
Boosted 2.2W Class D Amplifier
with Automatic Level Control
MAX98500
ELECTRICAL CHARACTERISTICS (continued)
(V
BAT
= 3.6V, R
L
=
J
between SPKP and SPKN, A
V
= +6dB, C
IN
= 1FF, 20Hz to 22kHz AC measurement bandwidth, T
A
= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
V
KNEE
= 3.25V
V
KNEE
= 3.35V
Knee Resistor
R
KNEE
T
A
= +25NC,
A
V
= 15.5dB
V
KNEE
= 3.45V
V
KNEE
= 3.55V
V
KNEE
= 3.65V
V
KNEE
= 3.75V
V
KNEE
= 3.85V
DIGITAL INPUTS (SDBST,
SDSPK)
Input Voltage High
Input Voltage Low
Input Capacitance
Input Leakage Current
V
iH
V
IL
C
IN
I
IN
T
A
= +25NC
-1.0
10
+1.0
1.4
0.4
MIN
TYP
43.2
37.4
32.4
27.4
23.2
18.7
15.0
V
V
pF
FA
kI
MAX
UNITS
Note 2:
100% production tested at T
A
= +25NC. Specifications over temperature limits are guaranteed by design.
Note 3:
Amplifier inputs are AC-coupled to AGND.
Note 4:
Mode transitions are controlled by
SDSPK.
4
______________________________________________________________________________________
Boosted 2.2W Class D Amplifier
with Automatic Level Control
Typical Operating Characteristics
(V
BAT
= 3.6V, R
L
= ∞ between SPKP and SPKN, A
V
= +15.5dB, RKNEE = V
BAT
, 20Hz to 22kHz AC measurement bandwidth, unless
otherwise noted.)
MAX98500
General
BATTERY CURRENT
vs. BATTERY VOLTAGE
4.5
4.0
BATTERY CURRENT (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
BATTERY VOLTAGE (V)
60
2.5
3.0
INPUTS AC-COUPLED TO AGND
SDSPK = SDBST = V
BAT
MAX98500 toc01
BATTERY CURRENT
vs. BATTERY VOLTAGE
INPUTS AC-COUPLED TO AGND
SDSPK = GND, SDBST = V
BAT
BATTERY CURRENT (µA)
120
MAX98500 toc02
5.0
140
100
80
3.5
4.0
4.5
5.0
5.5
BATTERY VOLTAGE (V)
BATTERY CURRENT
vs. BATTERY VOLTAGE
9
8
BATTERY CURRENT (µA)
7
6
5
4
3
2
1
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
OV
OV
TURN-ON RESPONSE
MAX98500 toc04
MAX98500 toc03
10
INPUTS AC-COUPLED TO AGND
SDSPK = V
BAT
, SDBST = AGND
SDBST
2V/div
OV
V
CCOUT
2V/div
SPKR
OUTPUT
1V/div
2ms/div
BATTERY VOLTAGE (V)
EFFICIENCY vs. OUTPUT POWER
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
0.5
1.0
V
BAT
= 4.2V
V
BAT
= 3.6V
V
BAT
= 3.0V
MAX98500 toc05
100
Z
LOAD
= 8I + 68µH
f
IN
= 1kHz
1.5
2.0
2.5
P
OUT
(W)
_______________________________________________________________________________________
5
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