The MAX98300 mono 2.6W Class D amplifier provides
Class AB audio performance with Class D efficiency.
This device offers five selectable gain settings (0dB,
3dB, 6dB, 9dB, and 12dB) set by a single gain-select
input (GAIN).
Active emissions-limiting edge-rate and overshoot control circuitry greatly reduces EMI. A patented filterless
spread-spectrum modulation scheme eliminates the need
for output filtering found in traditional Class D devices.
These features reduce application component count.
The MAX98300 industry-leading 0.78mA at 3.7V (1.1mA
at 5V) quiescent current extends battery life in portable
applications.
The MAX98300 is available in an 8-pin TDFN-EP (2mm
x 2mm x 0.8mm) and a 9-bump (1.2mm x 1.2mm) WLP.
Both packages are specified over the extended -40NC to
+85NC temperature range.
MAX98300
Features
S Industry-Leading Quiescent Current: 0.78mA at
3.7V, 1.1mA at 5V
S Spread Spectrum and Active Emissions Limiting
S Five Selectable Gains
S Click-and-Pop Suppression
S Thermal and Overcurrent Protection
S Low-Current Shutdown Mode
S Space-Saving Packages
2mm x 2mm x 0.8mm, 8-Pin TDFN-EP
1.2mm x 1.2mm, 9-Bump WLP (0.4mm Pitch)
Applications
Notebook and Netbook Computers
Cellular Phones
MP3 Players
Portable Audio Players
VoIP Phones
Ordering Information
PARTTEMP RANGEPIN-PACKAGE
MAX98300ETA+
MAX98300EWL+
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Junction Temperature .....................................................+150NC
Operating Temperature Range .......................... -40NC to +85NC
Storage Temperature Range ............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
MAX98300
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
PVDD
= V
SHDN
= 5.0V, V
= 0V, AV = 12dB (GAIN = PVDD), RL = J, RL connected between OUT+ to OUT-, AC measurement
PGND
= T
MIN
to T
A
, unless otherwise noted. Typical values are at TA = +25NC.) (Notes 1, 2)
MAX
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
AMPLIFIER CHARACTERISTICS
Speaker Supply Voltage RangePVDDInferred from PSRR test2.65.5V
Input-Voltage HighV
Input-Voltage LowV
Input Leakage Current
INH
INL
= +25NCQ10FA
T
A
1.4V
Note 1: All devices are 100% production tested at +25NC. All temperature limits are guaranteed by design.
Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R
L = 33FH. For RL = 8I, L = 68FH.
Note 3: Amplifier inputs AC-coupled to ground.
Note 4: Mode transitions controlled by SHDN.
The MAX98300 features industry-leading quiescent current, low-power shutdown mode, comprehensive clickand-pop suppression, and excellent RF immunity.
The device 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
MAX98300
significant improvements to switch-mode amplifier radiated emissions.
The MAX98300 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 MAX98300 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
2
R loss of the MOSFET on-resistance and quiescent
the I
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
patented active emissions-limiting edge-rate control
circuitry and spread-spectrum modulation reduces EMI
emissions, while maintaining up to 89% efficiency.
Maxim’s patented 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 MAX98300’s spread-spectrum
modulator randomly varies the switching frequency by
Q10kHz 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 MAX98300 disables the outputs for approximately 130Fs. At the end of 130Fs, the
outputs are re-enabled. If the fault condition still exists,
the MAX98300 continues to disable and re-enable the
outputs until the fault condition is removed.
Selectable Gain
The MAX98300 offers five programmable gain selections
through a single gain input (GAIN).
Table 1. Gain Control Configuration
GAIN PINMAXIMUM GAIN (dB)
Connect to PVDD12
Connect to PVDD through
100kI±5%
Not connected6
Connect to PGND through
100kI±5%
Connect to PGND0
9
3
50
40
30
20
10
AMPLITUDE (dBµV/m)
0
-10
301000
Figure 1. EMI with 60cm of Speaker Cable and No Output Filtering
The MAX98300 features a low-power shutdown mode,
drawing less than 0.1FA of supply current. Drive SHDN
low to put the MAX98300 into shutdown.
Click-and-Pop Suppression
The MAX98300 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.
Applications Information
Filterless Class D Operation
Traditional Class D amplifiers require an output filter.
The filter adds cost, size, and decreases efficiency and
THD+N performance. The MAX98300’s filterless modulation scheme does not require an output filter (Figure 1).
Because the switching frequency of the MAX98300 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 > 10FH. Typical
8I speakers exhibit series inductances in the 20FH to
100FH range.
Component Selection
Speaker Amplifier Power Supply Input (PVDD)
PVDD powers the speaker amplifier. PVDD ranges
from 2.6V to 5.5V. Bypass PVDD with a 0.1FF and 10FF
capacitor 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 (C
amplifier’s internal input resistance (R
pass filter that removes the DC bias from the incoming
signal. These capacitors allow the amplifier to bias the
signal to an optimum DC level.
), in conjunction with the
IN
), forms a high-
IN
Assuming zero source impedance with a gain setting of
= 6dB, 9dB, or 12dB, CIN is:
A
V
8
=µ
C[ F]
IN
f
3dB
−
with a gain setting of A
with a gain setting of A
where f
is the -3dB corner frequency. Use capaci-
-3dB
= 3dB, CIN is:
V
5.7
=µ
C[ F]
IN
f
3dB
−
= 0dB, CIN is:
V
4
=µ
C[ F]
IN
f
3dB
−
tors with adequately low voltage-coefficient for best lowfrequency THD performance.
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 load impedance decreases, the current drawn from the device
outputs increase. At higher current, the resistance of the
output traces decreases the power delivered to the load.
For example, if 2W is delivered from the speaker output
to a 4I load through a 100mI trace, 49mW is consumed
in the trace. If power is delivered through a 10mI trace,
only 5mW is consumed in the trace. Wide output, supply,
and ground traces also improve the power dissipation of
the device.
The MAX98300 is inherently designed for excellent RF
immunity. For best performance, add ground fills around
all signal traces on top or bottom PCB planes.
The MAX98300 TDFN-EP 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 the ground plane by using a large pad and
multiple vias.
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.
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.
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.
14 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600