The MAX98303 stereo 3.1W Class D amplifier provides
Class AB audio performance with Class D efficiency.
This device offers five selectable gain settings (6dB,
9dB, 12dB, 15dB, and 18dB) set by a single gain-select
input (GAIN).
Active emissions limiting, edge-rate, and overshoot control circuitry greatly reduces EMI. A filterless spreadspectrum modulation scheme eliminates the need for
output filtering found in traditional Class D devices. These
features reduce application component count.
The IC's 2.0mA at 3.7V, 2.7mA at 5V, quiescent current
extends battery life in portable applications.
The IC is available in a 16-bump WLP (1.68mm x 1.68mm
x 0.64mm) package specified over the extended -40NC
to +85NC temperature range.
Continuous Input Current (all other pins) ........................ Q20mA
Duration of Short Circuit Between
OUTL_, OUTR_ to PVDD or PGND ........................Continuous
OUTL+ to OUTL-, OUTR+ to OUTR- .................... Continuous
MAX98303
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.
PVDD
+ 0.3V)
ELECTRICAL CHARACTERISTICS
(V
= V
PVDD
AC measurement bandwidth, TA = T
Supply Voltage RangeV
Undervoltage LockoutUVLO2.3V
Quiescent Supply CurrentI
Shutdown Supply Current
Turn-On Timet
Bias VoltageV
Voltage GainA
Channel-to-Channel Gain
Tracking
Input ResistanceR
Output Offset VoltageV
= 3.7V, V
SHDN
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
= 0V, AV = 12dB (GAIN = PVDD), RL = J, RL connected between OUT_+ to OUT_-, 20Hz to 22kHz
PGND
MIN
to T
PVDD
DD
I
SHDN
ON
BIAS
OS
, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 2, 3)
MAX
Inferred from PSRR test2.65.5V
V
= 5.0V2.7
PVDD
V
= 0V, TA = +25NC
SHDN
Connect GAIN to PGND17.51818.5
Connect GAIN to PGND through 100kI±5% resistor
Connect GAIN to PVDD11.51212.5
V
Connect GAIN to PVDD through 100kI±5% resistor
GAIN unconnected 5.566.5
AV = 18dB 152029
AV = 15dB152029
AV = 12dB152029
IN
AV = 9dB202840
AV = 6dB304058
TA = +25NC (Note 4)
Continuous Power Dissipation for Multilayer Board (TA = +70NC)
Output Current LimitI
Thermal Shutdown Level145
Thermal Shutdown Hysteresis15
DIGITAL INPUT (SHDN)
MAX98303
Input Voltage HighV
Input Voltage LowV
Input Leakage Current
Note 2: This device is 100% production tested at TA = +25NC. All temperature limits are guaranteed by design.
Note 3: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For RL = 4I,
L = 33FH. For RL = 8I, L = 68FH.
Note 4: Amplifier inputs AC-coupled to ground.
Note 5: Mode transitions controlled by SHDN.
SHDN
= 3.7V, V
= 0V, AV = 12dB (GAIN = PVDD), RL = J, RL connected between OUT_+ to OUT_-, 20Hz to 22kHz
PGND
MIN
to T
, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 2, 3)
MAX
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
LIM
INH
INL
V
= 2.5V to 5.5V1.4V
PVDD
V
= 2.5V to 5.5V0.4V
PVDD
2A
TA = +25NC
±1
NC
NC
FA
Typical Operating Characteristics
(V
= V
PVDD
bandwidth, TA = +25NC, unless otherwise noted.)
10
1
THD+N (%)
0.1
0.01
10100k
SHDN
= 5.0V, V
= 0V, AV = 12dB, RL = J, RL connected between OUT_+ to OUT_-, 20Hz to 22kHz AC measurement
A1OUTL+Positive Left Speaker Output
A2OUTL-Negative Left Speaker Output
A3GAINGain Select. See Table 1 for Gain Settings.
A4INL+Noninverting Audio Left Input
B1, B2, B3PGNDGround
B4INL-Inverting Audio Left Input
C1, C2, C3PVDD
C4INR-Inverting Audio Right Input
D1OUTR+Positive Right Speaker Output
D2OUTR-Negative Right Speaker Output
D3
D4INR+Noninverting Audio Right Input
SHDNActive-Low Shutdown Input. Drive SHDN low to place the device in shutdown.
Power Supply. Bypass PVDD to PGND with 0.1FF and 10FF capacitors.
The MAX98303 features low quiescent current, a lowpower shutdown mode, comprehensive click-and-pop
suppression, and excellent RF immunity.
The IC offers Class AB audio performance with Class D
efficiency in a minimal board-space solution.
The Class D amplifier features spread-spectrum modulation, edge-rate, and overshoot control circuitry that
offers significant improvements to switch-mode amplifier
radiated emissions.
The amplifier features click-and-pop suppression that
reduces audible transients on startup and shutdown.
The amplifier includes thermal-overload and short-circuit
protection.
Class D Speaker Amplifier
The filterless Class D amplifier offers much higher efficiency than Class AB amplifiers. The high efficiency of
a Class D amplifier is due to the switching operation of
the output stage transistors. Any power loss associated
with the Class D output stage is mostly due to the I2R
loss of the MOSFET on-resistance and quiescent current
overhead.
Ultra-Low-EMI Filterless Output Stage
Traditional Class D amplifiers require the use of external
LC filters, or shielding, to meet EN55022B electromagnetic-interference (EMI) regulation standards. Maxim’s active
emissions limiting edge-rate control circuitry and spreadspectrum modulation reduce EMI emissions, while maintaining up to 93% efficiency.
Maxim’s spread-spectrum modulation mode flattens
wideband spectral components, while proprietary techniques ensure that the cycle-to-cycle variation of the
switching period does not degrade audio reproduction
or efficiency. The IC’s spread-spectrum modulator randomly varies the switching frequency by Q15kHz around
the center frequency (300kHz). Above 10MHz, the
wideband spectrum looks like noise for EMI purposes
(Figure 1).
Speaker Current Limit
If the output current of the speaker amplifier exceeds
the current limit (2A typ), the IC disables the outputs for
approximately 100Fs. At the end of 100Fs, the outputs
are reenabled. If the fault condition still exists, the IC
continues to disable and reenable the outputs until the
fault condition is removed.
Selectable Gain
The IC offers five programmable gains selected using
the GAIN input.
Table 1. Gain Control Configuration
GAIN PINMAXIMUM GAIN (dB)
Connect to PGND18
Connect to PGND through
100kI±5% resistor
Connect to PVDD12
Connect to PVDD through
100kI±5% resistor
Unconnected6
90
70
50
EN55022B LIMIT
30
EMISSIONS LEVEL (dBµV/m)
10
-10
Figure 1. EMI with 30cm of Speaker Cable and No Output Filter
HORIZONTAL
VERTICAL
0 100 200 300 400 500 600 700 800 900 1000
FREQUENCY (MHz)
The IC features a low-power shutdown mode, drawing
P 0.1FA (typ) of supply current. Drive SHDN low to place
the MAX98303 into shutdown.
Click-and-Pop Suppression
The IC 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 ramp down to
PGND quickly and simultaneously.
Traditional Class D amplifiers require an output filter.
The filter adds cost and size and decreases THD performance. The IC’s filterless modulation scheme does not
require an output filter.
Because the switching frequency of the IC is well
beyond the bandwidth of most speakers, voice coil
MAX98303
movement due to the switching frequency is very small.
Use a speaker with a series inductance > 10FH. Typical
8I speakers exhibit series inductances in the 20FH to
100FH range.
Component Selection
Power-Supply Input (PVDD)
PVDD powers the speaker amplifier. PVDD ranges from
2.6V to 5.5V. Bypass PVDD with 0.1FF and 10FF capacitors to PGND. Apply additional bulk capacitance at the
device if long input traces between PVDD and the power
source are used.
Input Filtering
The input-coupling capacitor (CIN), in conjunction with
the amplifier’s internal input resistance (RIN), forms a
highpass filter that removes the DC bias from the incoming signal. These capacitors allow the amplifier to bias
the signal to an optimum DC level.
Assuming zero source impedance with a gain setting of
12dB, 15dB, or 18dB, CIN is:
8
=µ
C[ F]
IN
f
3dB
−
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Good grounding improves audio performance and prevents switching noise from coupling into
the audio signal.
Use wide, low-resistance output traces. As the load
impedance decreases, the current drawn from the
device increases. At higher current, the resistance of the
output traces decrease the power delivered to the load.
For example, if 2W is delivered from the device output to
a 4I load through 100mI of total speaker trace, 1.904W
is delivered to the speaker. If power is delivered through
10mI of total speaker trace, 1.99W is delivered to the
speaker. Wide output, supply, and ground traces also
improve the power dissipation of the device.
The IC is inherently designed for excellent RF immunity.
For best performance, add ground fills around all signal
traces on top or bottom PCB planes.
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
testing results, refer to Application Note 1891: Wafer level packaging (WLP)and its applications. Figure 2
shows the dimensions of the WLP balls used on the IC.
0.24mm
with a gain setting of 9dB, CIN is:
5.7
=µ
C[ F]
IN
f
3dB
−
with a gain setting of 6dB, CIN is:
4
=µ
C[ F]
IN
f
−
3dB
where f
tors with adequately low-voltage coefficients for best
low-frequency THD performance.
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.
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 13