19-6278; Rev 0; 5/12
EVALUATION KIT AVAILABLE
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
General Description
The MAX98355A/MAX98355B are digital pulse-code
modulation (PCM) input Class D power amplifiers that
provide Class AB audio performance with Class D effi-
ciency. These ICs offer five selectable gain settings
(3dB, 6dB, 9dB, 12dB, and 15dB) set by a single gain-
select input (GAIN).
The digital audio interface is highly flexible with the
MAX98355A supporting I
2
S data and the MAX98355B
supporting left-justified data. Both ICs support time divi-
sion multiplexed (TDM) data. The digital audio interface
accepts sample rates ranging from 8kHz to 96kHz for all
supported data formats. The ICs can be configured to
produce a left channel, right channel, or (left + right)/2
output from the stereo input data. The ICs operate using
16/24/32-bit data for I
2
S and left justified modes as well
as 16-bit data with up to four slots when using TDM
mode. The ICs eliminate the need for the external MCLK
signal that is typically used for PCM communication. This
reduces EMI and possible board coupling issues in addi-
tion to reducing the size and pin count of the ICs.
The ICs also feature a very high wideband jitter tolerance
(12ns typ) on BCLK and LRCLK to provide robust operation.
Active emissions-limiting, edge-rate limiting, and over-
shoot control circuitry greatly reduce EMI. A filterless
spread-spectrum modulation scheme eliminates the
need for output filtering found in traditional Class D
devices and reduces the component count of the solution.
The ICs are available in a 9-pin WLP package (1.345mm
x 1.435mm x 0.64mm) and are specified over the -40NC
to +85NC temperature range.
S
3.2W Output Power into 4I at 5V
S
2.2mA Quiescent Current
S
92% Efficiency (R
L
= 8I, P
OUT
= 900mW,
V
DD
= 3.7V)
S
25µV
RMS
Output Noise (A
V
= 15dB)
S
Low 0.013% THD+N at 1kHz
S
No MCLK Required
S
Sample Rates of 8kHz to 96kHz
S
Supports Left, Right, or (Left + Right)/2 Outputs
S
Sophisticated Edge Rate Control Enables
Filterless Class D Outputs
S
77dB PSRR at 217Hz
S
Low RF Susceptibility Rejects TDMA
Noise from GSM Radios
S
Extensive Click-and-Pop Reduction Circuitry
S
Robust Short-Circuit and Thermal Protection
S
Available in Space-Saving Package:
1.345mm x 1.435mm WLP (0.4mm Pitch)
Features
S
Single-Supply Operation (2.5V to 5.5V)
Simplified Block Diagram
Applications
Cellular Phones
Tablets
Portable Media Players
Notebook Computers
Ordering Information
appears at end of data sheet.
Functional Diagram
appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to
www.maxim-ic.com/MAX98355A.related.
PCM
INPUT
SHUTDOWN
AND
CHANNEL
SELECT
DIGITAL
AUDIO
INTERFACE
MAX98355A
MAX98355B
GAIN
CONTROL
DAC
CLASS D
OUTPUT
STAGE
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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.
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
TABLE OF CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Package Thermal Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Speaker Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Digital Audio Interface Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
MCLK Elimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Jitter Tolerance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
BCLK Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
LRCLK Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
PCM Timing Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
DAC Digital Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
SD_MODE
and Shutdown Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Class D Speaker Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Ultra-Low EMI Filterless Output Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Speaker Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Click-and-Pop Suppression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Applications Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Filterless Class D Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Power-Supply Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Layout and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
WLP Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Functional Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Package Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
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Maxim Integrated Products
2
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
LIST OF FIGURES
Figure 1. I
2
S Audio Interface Timing Diagram (MAX98355A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 2. Left-Justified Audio Interface Timing Diagram (MAX98355B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3. TDM Audio Interface Timing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. MAX98355A I
2
S Digital Audio Interface Timing, 16-Bit Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 5. MAX98355A I
2
S Digital Audio Interface Timing, 24-Bit Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 6. MAX98355B Left-Justified Digital Audio Interface Timing, 16-Bit Resolution . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 7. MAX98355B Left-Justified Digital Audio Interface Timing, 24-Bit Resolution. . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 8. MAX98355A TDM Digital Audio Interface Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 9. MAX98355B TDM Digital Audio Interface Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 10. MAX98355A TDM Digital Audio Interface Timing, Example of Four 16-Bit Slots. . . . . . . . . . . . . . . . . . . . 24
Figure 11. MAX98355B TDM Digital Audio Interface Timing, Example of Four 16-Bit Slots . . . . . . . . . . . . . . . . . . . . 25
Figure 12.
SD_
MODE
Resistor Connection Using Open-Drain Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 13.
SD_
MODE
Resistor Connection Using Pullup/Down Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 14. EMI with 12in of Speaker Cable and No Output Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 15. Left-Channel PCM Operation with 6dB Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 16. Left-Channel PCM Operation with 12dB Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 17. Right-Channel PCM Operation with 6dB Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 18. Stereo PCM Operation Using Two ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 19. (Left + Right)/2 PCM Operation with 6dB Gain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 20. MAX98355A/MAX98355B WLP Ball Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
LIST OF TABLES
Table 1. RMS Jitter Tolerance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 2. BCLK Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 3. LRCLK Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 4. Digital Filter Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 5.
SD_MODE
Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 6. Examples of
SD_MODE
Pullup Resistor Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 7. Gain Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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Maxim Integrated Products
3
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ABSOLUTE MAXIMUM RATINGS
V
DD
, LRCLK, BCLK, and DIN to GND ....................-0.3V to +6V
All Other Pins to GND .............................. -0.3V to (V
DD
+ 0.3V)
Continuous Current In/Out of V
DD
/GND/OUT_ .................
Q1.6A
Continuous Input Current (all other pins) ........................
Q20mA
Duration of OUT_ Short Circuit to GND or V
DD
….....Continuous
Duration of OUTP Short to OUTN .............................Continuous
Continuous Power Dissipation (T
A
= +70NC)
WLP (derate 13.7mW/NC above +70NC)....................1096mW
Junction Temperature .....................................................+150NC
Operating Temperature Range .......................... -40NC to +85NC
Storage Temperature Range............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+230NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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 (Note 1)
WLP
Junction-to-Ambient Thermal Resistance (q
JA
) ..........73°C/W
Junction-to-Case Thermal Resistance (q
JC
) ...............50°C/W
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.
ELECTRICAL CHARACTERISTICS
(V
DD
= 5V, V
GND
= 0V, GAIN = V
DD
(+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (Z
SPK
) connected between OUTP
and OUTN, Z
SPK
=
J,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER
Supply Voltage Range
Undervoltage Lockout
Quiescent Current
Shutdown Current
Standby Current
Turn-On Time
Output Offset Voltage
SYMBOL
V
DD
UVLO
I
DD
I
SHDN
I
STNDBY
t
ON
V
OS
T
A
= +25NC
T
A
= +25NC, V
DD
= 3.7V
SD_MODE
= 0V, T
A
= +25NC
SD_MODE
= 1.8V, no BCLK, T
A
= +25NC
Time from receipt of first clock cycle
to full operation, including 6ms fade-in
volume ramp
T
A
= +25NC, gain = 15dB
Peak voltage, T
A
= Into shutdown
+25NC, A-weighted,
32 samples per
Out of shutdown
second (Note 3)
V
DD
= 2.5V to 5.5V, T
A
= +25NC
Power-Supply Rejection Ratio
PSRR
T
A
= +25NC
(Notes 3, 4)
f = 217Hz,
200mV
P-P
ripple
f = 10kHz,
200mV
P-P
ripple
60
CONDITIONS
Guaranteed by PSSR test
MIN
2.5
1.5
1.8
2.5
2.2
0.6
300
7
Q0.3
-66
dBV
-72
75
77
60
dB
TYP
MAX
5.5
2.2
3.3
2.7
2
400
7.5
Q1.5
UNITS
V
V
mA
FA
FA
ms
mV
Click-and-Pop Level
K
CP
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Maxim Integrated Products
4
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 5V, V
GND
= 0V, GAIN = V
DD
(+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (Z
SPK
) connected between OUTP
and OUTN, Z
SPK
=
J,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER
SYMBOL
THD+N 10%,
gain = 12dB
Output Power (Note 3)
P
OUT
THD+N = 1%,
gain = 12dB
CONDITIONS
Z
SPK
= 4I + 33FH
Z
SPK
= 8I + 68FH
Z
SPK
= 8I + 68FH,
V
DD
= 3.7V
Z
SPK
= 4I + 33FH
Z
SPK
= 8I + 68FH
Z
SPK
= 8I + 68FH,
V
DD
= 3.7V
MIN
TYP
3.2
1.8
0.93
2.5
1.4
0.77
0.02
0.013
99
105
25
25
14.5
11.5
8.5
5.5
2.5
15
12
9
6
3
2.8
Z
SPK
= 8I + 68FH, THD+N = 10%,
f = 1kHz, gain = 12dB
-0.2
92
1
+0.2
15.5
12.5
9.5
6.5
3.5
A
%
%
dB
dB
dB
dB
FV
RMS
FV
RMS
0.06
%
W
MAX
UNITS
Total Harmonic Distortion +
Noise
Dynamic Range
Dynamic Range, High Gain
Output Noise
Output Noise, High Gain
THD+N
f = 1kHz, P
OUT
= 1W, T
A
= +25NC,
Z
SPK
= 4I + 33FH
f = 1kHz, P
OUT
= 0.5W, T
A
= +25NC,
Z
SPK
= 8I + 68FH
A-weighted,
V
RMS
= 2.54V, 24- or 32-bit data
A-weighted, gain = 15dB, V
RMS
= 4.55V
(clipping), 24- or 32-bit data
A-weighted, 24- or 32-bit data (Note 4)
A-weighted, gain = 15dB, 24- or 32-bit
data (Note 4)
GAIN = GND through 100kI
GAIN = GND
DR
DR
HG
V
N
V
N_HG
Gain (Relative to a 2.1dBV
Reference Level)
A
V
GAIN = unconnected
GAIN = V
DD
GAIN = V
DD
through 100kI
Current Limit
Efficiency
DAC Gain Error
Frequency Response
DAC DIGITAL FILTERS
I
LIM
h
VOICE MODE IIR LOWPASS FILTER (LRCLK < 30kHz)
Ripple limit cutoff
Passband Cutoff
f
PLP
-3dB cutoff
Stopband Cutoff
Stopband Attenuation
f
SLP
f > f
SLP
75
0.443
x f
S
0.446
x f
S
0.464
x f
S
Hz
Hz
dB
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
5
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