MAXIM MAX98355A

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 efficiency. These ICs offer five selectable gain settings
(3dB, 6dB, 9dB, 12dB, and 15dB) set by a single gainselect input (GAIN).
The digital audio interface is highly flexible with the
MAX98355A supporting I2S data and the MAX98355B
supporting left-justified data. Both ICs support time division 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 I2S 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 addition 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 overshoot 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.
Features
SSingle-Supply Operation (2.5V to 5.5V)
S3.2W Output Power into 4I at 5V
S2.2mA Quiescent Current
S92% Efficiency (RL = 8I, POUT = 900mW,
VDD = 3.7V)
S25µVRMS Output Noise (AV = 15dB)
SLow 0.013% THD+N at 1kHz
SNo MCLK Required
SSample Rates of 8kHz to 96kHz
SSupports Left, Right, or (Left + Right)/2 Outputs
SSophisticated Edge Rate Control Enables
Filterless Class D Outputs
S77dB PSRR at 217Hz
SLow RF Susceptibility Rejects TDMA
Noise from GSM Radios
SExtensive Click-and-Pop Reduction Circuitry
SRobust Short-Circuit and Thermal Protection
SAvailable in Space-Saving Package:
1.345mm x 1.435mm WLP (0.4mm Pitch)
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.
Simplified Block Diagram
Applications
Cellular Phones
SHUTDOWN
AND
CHANNEL
SELECT
Tablets
Portable Media Players
Notebook Computers
Ordering Information appears at end of data sheet.
Functional Diagram appears at end of data sheet.
PCM
INPUT
DIGITAL
AUDIO
INTERFACE
MAX98355A
MAX98355B
DAC
GAIN
CONTROL
CLASS D
OUTPUT
STAGE
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX98355A.related.
����������������������������������������������������������������� 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
����������������������������������������������������������������� Maxim Integrated Products 2
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
LIST OF FIGURES
Figure 1. I2S 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 I2S Digital Audio Interface Timing, 16-Bit Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 5. MAX98355A I2S 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
����������������������������������������������������������������� Maxim Integrated Products 3
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ABSOLUTE MAXIMUM RATINGS
VDD, LRCLK, BCLK, and DIN to GND.....................-0.3V to +6V
All Other Pins to GND............................... -0.3V to (VDD + 0.3V)
Continuous Current In/Out of VDD/GND/OUT_.................. Q1.6A
Continuous Input Current (all other pins)......................... Q20mA
Duration of OUT_ Short Circuit to GND or VDD…......Continuous
Duration of OUTP Short to OUTN..............................Continuous
Continuous Power Dissipation (TA = +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 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 (Note 1)
WLP
Junction-to-Ambient Thermal Resistance (qJA)...........73°C/W
Junction-to-Case Thermal Resistance (qJC)................50°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
Supply Voltage Range
VDD
Undervoltage Lockout
UVLO
Quiescent Current
IDD
Shutdown Current
ISHDN
Standby Current
ISTNDBY
CONDITIONS
Guaranteed by PSSR test
1.5
UNITS
5.5
V
V
2.2
2.5
3.3
TA = +25NC, VDD = 3.7V
2.2
2.7
mA
SD_MODE = 0V, TA = +25NC
0.6
2
FA
SD_MODE = 1.8V, no BCLK, TA = +25NC
Time from receipt of first clock cycle
to full operation, including 6ms fade-in
volume ramp
300
400
FA
7
7.5
ms
Q0.3
Q1.5
mV
Output Offset Voltage
VOS
TA = +25NC, gain = 15dB
KCP
Peak voltage, TA = Into shutdown
+25NC, A-weighted,
32 samples per
Out of shutdown
second (Note 3)
PSRR
MAX
1.8
tON
Power-Supply Rejection Ratio
TYP
2.5
TA = +25NC
Turn-On Time
Click-and-Pop Level
MIN
VDD = 2.5V to 5.5V, TA = +25NC
f = 217Hz,
200mVP-P ripple
TA = +25NC
(Notes 3, 4)
f = 10kHz,
200mVP-P ripple
-66
dBV
-72
60
75
77
dB
60
����������������������������������������������������������������� Maxim Integrated Products 4
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
THD+N 10%,
gain = 12dB
Output Power (Note 3)
POUT
THD+N = 1%,
gain = 12dB
Total Harmonic Distortion +
Noise
Dynamic Range
THD+N
Output Noise
Output Noise, High Gain
3.2
ZSPK = 8I + 68FH
1.8
ZSPK = 8I + 68FH,
VDD = 3.7V
0.93
ZSPK = 4I + 33FH
2.5
ZSPK = 8I + 68FH
1.4
ZSPK = 8I + 68FH,
VDD = 3.7V
0.77
f = 1kHz, POUT = 1W, TA = +25NC,
ZSPK = 4I + 33FH
0.02
f = 1kHz, POUT = 0.5W, TA = +25NC,
ZSPK = 8I + 68FH
0.013
MAX
UNITS
W
0.06
%
99
dB
A-weighted, gain = 15dB, VRMS = 4.55V
(clipping), 24- or 32-bit data
105
dB
VN
A-weighted, 24- or 32-bit data (Note 4)
25
FVRMS
VN_HG
A-weighted, gain = 15dB, 24- or 32-bit
data (Note 4)
25
FVRMS
DRHG
Gain (Relative to a 2.1dBV
Reference Level)
AV
Current Limit
ILIM
Efficiency
TYP
A-weighted,
VRMS = 2.54V, 24- or 32-bit data
DR
Dynamic Range, High Gain
MIN
ZSPK = 4I + 33FH
h
GAIN = GND through 100kI
14.5
15
15.5
GAIN = GND
11.5
12
12.5
GAIN = unconnected
8.5
9
9.5
GAIN = VDD
GAIN = VDD through 100kI
5.5
6
6.5
3
3.5
2.5
ZSPK = 8I + 68FH, THD+N = 10%,
f = 1kHz, gain = 12dB
DAC Gain Error
Frequency Response
-0.2
dB
2.8
A
92
%
1
%
+0.2
dB
DAC DIGITAL FILTERS
VOICE MODE IIR LOWPASS FILTER (LRCLK < 30kHz)
Passband Cutoff
Ripple limit cutoff
0.443
x fS
-3dB cutoff
0.446
x fS
fPLP
Stopband Cutoff
0.464
x fS
fSLP
Stopband Attenuation
Hz
f > fSLP
75
Hz
dB
����������������������������������������������������������������� Maxim Integrated Products 5
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AUDIO MODE FIR LOWPASS FILTER (30kHz < LRCLK < 50kHz)
Passband Cutoff
fPLP
Stopband Cutoff
Ripple limit cutoff
0.43
x fS
-3dB cutoff
0.47
x fS
-6.02dB cutoff
0.5
x fS
Hz
0.58
x fS
fSLP
Stopband Attenuation
f > fSLP
AUDIO MODE FIR LOWPASS FILTER (LRCLK > 50kHz)
Passband Cutoff
Ripple limit cutoff
0.24
x fS
-3dB cutoff
0.31
x fS
fPLP
Stopband Cutoff
60
dB
Hz
0.477
x fS
fSLP
Stopband Attenuation
f < fSLP
Hz
60
Hz
dB
DIGITAL AUDIO INTERFACE
LRCLK Range 1
fS1
7.6
8
8.4
LRCLK Range 2
fS2
15.2
16
16.8
LRCLK Range 3
fS3
30.4
48
50.4
LRCLK Range 4
fS4
96
100.8
83.8
I2S/left justified mode
Resolution
16/24/32
TDM mode
BCLK Frequency Range
fBCLK
BCLK must be 32, 48, or 64X of LRCLK
Bits
16
0.2432
kHz
6.4512
MHz
BCLK High Time
tBCLKH
40
ns
BCLK Low Time
tBCLKL
40
ns
Maximum Low Frequency
BCLK and LRCLK Jitter
RMS jitter below 40kHz
0.5
Maximum High Frequency
BCLK and LRCLK Jitter
RMS jitter above 40kHz
12
ns
Input High Voltage
VIH
Digital audio inputs
Input Low Voltage
VIL
Digital audio inputs
1.3
V
0.6
V
����������������������������������������������������������������� Maxim Integrated Products 6
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
Input Leakage Current
Input Capacitance
SYMBOL
IIH, IIL
CONDITIONS
VIN = 0V, VDD = 5.5V, TA = +25NC
MIN
CIN
DIN to BCLK Setup Time
LRCLK to BCLK Setup Time
DIN to BCLK Hold Time
LRCLK to BCLK Hold Time
TYP
-1
MAX
UNITS
+1
FA
12
tSETUP
10
tSYNCSET
10
tHOLD
10
tSYNCHOLD
10
pF
ns
SD_MODE COMPARATOR TRIP POINTS
B0
See SD_MODE and shutdown operation
for details
B1
B2
SD_MODE Pulldown Resistor
RPD
0.08
0.16
0.355
0.65
0.77
0.825
1.245
1.4
1.5
92
100
108
V
kI
GAIN COMPARATOR TRIP POINTS
VGAIN
AV = 3dB gain
0.65 x
VDD
0.85 x
VDD
AV = 6dB gain
0.9 x
VDD
VDD
AV = 9dB gain
0.4 x
VDD
0.6 x
VDD
AV = 12dB gain
0
0.1 x
VDD
AV = 15dB gain
0.15 x
VDD
0.35 x
VDD
V
Note 2: 100% production tested at TA = +25NC. Specifications over temperature limits are guaranteed by design.
Note 3: Class D amplifier testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For
RL = 8I, LL = 68FH. For RL = 4I, LL = 33FH.
Note 4: Digital silence used for input signal.
����������������������������������������������������������������� Maxim Integrated Products 7
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
tBCLK
tBCLKH
tBCLKL
BCLK (INPUT)
tSYNCSET
tSYNCHOLD
LRCLK (INPUT)
tSETUP tHOLD
DIN (INPUT)
LSB
MSB
LSB
MSB
Figure 1. I2S Audio Interface Timing Diagram (MAX98355A)
tBCLK
tBCLKH
tBCLKL
BCLK (INPUT)
tSYNCSET
tSYNCHOLD
LRCLK (INPUT)
tSETUP tHOLD
DIN (INPUT)
LSB
MSB
LSB
MSB
Figure 2. Left-Justified Audio Interface Timing Diagram (MAX98355B)
tBCLK
tBCLK
tBCLKH
tBCLKL
tBCLKL
BCLK (INPUT)
tSYNCSET
tSYNCSET
tSYNCHOLD
LRCLK (INPUT)
tSYNCHOLD
LRCLK (INPUT)
tSETUP tHOLD
DIN (INPUT)
tBCLKH
BCLK (INPUT)
LSB
MSB
MAX98355A
tSETUP tHOLD
DIN (INPUT)
LSB
MSB
MAX98355B
Figure 3. TDM Audio Interface Timing Diagram
����������������������������������������������������������������� Maxim Integrated Products 8
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
General
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX98355A/B toc02
3.0
0.6
SHUTDOWN CURRENT (µA)
3.5
SUPPLY CURRENT (mA)
0.7
MAX98355A/B toc01
4.0
2.5
2.0
1.5
1.0
0.5
0.4
0.3
0.2
0.1
0.5
0
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
SUPPLY VOLTAGE (V)
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
Speaker Amplifier
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
-40
-50
f = 6kHz
-60
f = 1kHz
-70
-80
-30
-40
-50
f = 6kHz
-60
-70
f = 1kHz
-80
f = 100Hz
0.001
0.01
0.1
OUTPUT POWER (W)
1
10
-100
0
-10
-20
VDD = 5V
GAIN = 12dB
ZSPK = 8I + 68µH
-30
-40
-50
f = 6kHz
-60
-70
f = 1kHz
-80
f = 100Hz
-90
-90
-100
-20
VDD = 4.2V
GAIN = 12dB
ZSPK = 8I + 68µH
THD+N RATIO (dB)
-30
-10
MAX98355A/B toc04
VDD = 3.7V
GAIN = 12dB
ZSPK = 8I + 68µH
THD+N RATIO (dB)
THD+N RATIO (dB)
-20
0
MAX98355A/B toc03
0
-10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX98355A/B toc05
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
0.001
0.01
0.1
OUTPUT POWER (W)
f = 100Hz
-90
1
10
-100
0.001
0.01
0.1
1
10
OUTPUT POWER (W)
����������������������������������������������������������������� Maxim Integrated Products 9
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
f = 6kHz
-60
f = 1kHz
-70
-80
f = 100Hz
0.01
0.1
1
-50
f = 6kHz
-60
-70
f = 1kHz
1
-100
10
100
0.001
0.01
0.1
1
THD+N RATIO (dB)
-20
-30
-40
-50
-60
POUT = 100mW
-70
1k
FREQUENCY (Hz)
10k
100k
VDD = 5V
GAIN = 12dB
ZSPK = 8I + 68µH
-20
-30
-40
-50
-60
POUT = 150mW
-70
-80
POUT = 500mW
-90
-100
0
-10
10
MAX98355A/B toc11
VDD = 4.2V
GAIN = 12dB
ZSPK = 8I + 68µH
THD+N RATIO (dB)
MAX98355A/B toc09
0
-10
-80
POUT = 350mW
10
f = 100Hz
-90
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
POUT = 75mW
-90
f = 1kHz
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
-50
-80
0.1
-70
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
-40
-70
0.01
f = 6kHz
-60
OUTPUT POWER (W)
-30
-60
0.001
-50
OUTPUT POWER (W)
VDD = 3.7V
GAIN = 12dB
ZSPK = 8I + 68µH
-20
-100
10
-40
-80
f = 100Hz
-90
-30
OUTPUT POWER (W)
0
THD+N RATIO (dB)
-40
VDD = 5V
GAIN = 12dB
ZSPK = 4I + 33µH
-20
MAX98355A/B toc10
0.001
-10
-100
-30
-80
-90
-100
0
-10
THD+N RATIO (dB)
-40
-50
-20
THD+N RATIO (dB)
THD+N RATIO (dB)
-30
VDD = 4.2V
GAIN = 12dB
ZSPK = 4I + 33µH
-10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX98355A/B toc07
VDD = 3.7V
GAIN = 12dB
ZSPK = 4I + 33µH
-20
0
MAX98355A/B toc06
0
-10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX98355A/B toc08
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
10
100
POUT = 850mW
-90
1k
FREQUENCY (Hz)
10k
100k
-100
10
100
1k
10k
100k
FREQUENCY (Hz)
���������������������������������������������������������������� Maxim Integrated Products 10
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
-50
-60
POUT = 150mW
-80
-40
-50
-60
-70
POUT = 250mW
POUT = 600mW
1k
10k
-100
100k
10
1.5
THD+N = 10%
1.0
0.5
THD+N = 1%
1k
10k
LOAD (I)
POUT = 350mW
10
100
100
1k
10k
100k
OUTPUT POWER vs. LOAD RESISTANCE
2.0
THD+N = 10%
1.5
MAX98355A/B toc14
POUT = 1.5W
FREQUENCY (Hz)
1.0
4.5
VDD = 5V
GAIN = 12dB
ZSPK = RLOAD I + 68µH
4.0
3.5
3.0
2.5
THD+N = 10%
2.0
1.5
1.0
THD+N = 1%
THD+N = 1%
0.5
0
10
-70
-100
100k
VDD = 4.2V
GAIN = 12dB
ZSPK = RLOAD I + 68µH
2.5
0.5
0
1
-60
OUTPUT POWER vs. LOAD RESISTANCE
OUTPUT POWER (W)
2.0
100
3.0
MAX98355A/B toc15
VDD = 3.7V
GAIN = 12dB
ZSPK = RLOAD I + 68µH
-50
FREQUENCY (Hz)
OUTPUT POWER vs. LOAD RESISTANCE
2.5
-40
-90
OUTPUT POWER (W)
100
POUT = 850mW
-90
MAX98355A/B toc16
10
-30
-80
FREQUENCY (Hz)
OUTPUT POWER (W)
-20
-80
-90
-100
-30
VDD = 5V
GAIN = 12dB
ZSPK = 4I + 33µH
-10
THD+N RATIO (dB)
-40
-70
-20
THD+N RATIO (dB)
THD+N RATIO (dB)
-30
VDD = 4.2V
GAIN = 12dB
ZSPK = 4I + 33µH
-10
0
MAX98355A/B toc13
VDD = 3.7V
GAIN = 12dB
ZSPK = 4I + 33µH
-20
0
MAX98355A/B toc12
0
-10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX98355A/B toc17
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0
1
10
LOAD (I)
100
1
10
100
LOAD (I)
���������������������������������������������������������������� Maxim Integrated Products 11
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
OUTPUT POWER vs. SUPPLY VOLTAGE
THD+N = 10%
1.0
THD+N = 1%
0.5
0
THD+N = 10%
2.5
2.0
1.5
THD+N = 1%
1.0
3.0
3.5
4.0
4.5
5.0
3.0
4.0
4.5
5.0
50
40
30
10
0
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
OUTPUT POWER PER CHANNEL (W)
1k
10k
100k
EFFICIENCY vs. OUTPUT POWER
100
MAX98355A/B toc22
90
80
70
60
50
40
90
80
70
60
50
40
30
30
VDD = 3.7V
GAIN = 12dB
ZSPK = 8I + 68µH
100
FREQUENCY (Hz)
EFFICIENCY (%)
60
20
10
5.5
EFFICIENCY vs. OUTPUT POWER
EFFICIENCY (%)
70
3.5
100
MAX98355A/B toc21
80
-1
SUPPLY VOLTAGE (V)
EFFICIENCY vs. OUTPUT POWER
90
0
-3
2.5
SUPPLY VOLTAGE (V)
100
1
-2
0.5
5.5
MAX98355A-B toc20
3.0
ZSPK = 8I + 68µH
2
0
2.5
EFFICIENCY (%)
MAX98355A/B toc19
GAIN = 12dB
ZSPK = 4I + 33µH
3.5
NORMALIZED GAIN vs. FREQUENCY
3
MAX98355A/B toc23
1.5
OUTPUT POWER PER CHANNEL (W)
2.0
OUTPUT POWER (W)
MAX98355A/B toc18
GAIN = 12dB
ZSPK = 8I + 68µH
4.0
NORMALIZED GAIN (dB)
OUTPUT POWER vs. SUPPLY VOLTAGE
2.5
20
20
VDD = 4.2V
GAIN = 12dB
ZSPK = 8I + 68µH
10
0
0
0.2
0.4
0.6
0.8
1.0
1.2
OUTPUT POWER PER CHANNEL (W)
VDD = 5V
GAIN = 12dB
ZSPK = 8I + 68µH
10
0
1.4
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
OUTPUT POWER PER CHANNEL (W)
���������������������������������������������������������������� Maxim Integrated Products 12
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
EFFICIENCY vs. OUTPUT POWER
50
40
30
80
60
50
40
30
20
0
0
0
2.0
MAX98355A-B toc27
100
PSRR (dB)
60
40
20
20
f = 1kHz
ZSPK = 8I + 68µH
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT POWER PER CHANNEL (W)
INBAND OUTPUT SPECTRUM
40
30
VDD = 5V
GAIN = 12dB
ZSPK = 4I + 33µH
0
50
30
40
2.5
20
BCLK = 6.144MHz
LRCLK = 96kHz
ZSPK = 8I + 68µH
0
-20
AMPLITUDE (dBV)
80
60
50
VDD = 5V
ZSPK = 8I + 68µH
90
70
50
10
MAX98355A-B toc28
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
70
2.5
1.5
POWER-SUPPLY REJECTION RATIO
vs. SUPPLY VOLTAGE
80
0
1.0
OUTPUT POWER PER CHANNEL (W)
90
10
0.5
OUTPUT POWER PER CHANNEL (W)
100
60
20
VDD = 4.2V
GAIN = 12dB
ZSPK = 4I + 33µH
10
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
70
30
20
VDD = 3.7V
GAIN = 12dB
ZSPK = 4I + 33µH
10
PSRR (dB)
90
MAX98355A/B toc29
60
70
MAX98355A/B toc26
80
EFFICIENCY (%)
70
90
EFFICIENCY (%)
80
EFFICIENCY vs. OUTPUT POWER
100
MAX98355A/B toc25
90
EFFICIENCY (%)
EFFICIENCY vs. OUTPUT POWER
100
MAX98355A/B toc24
100
-40
-60
-80
-100
10
-120
0
-140
10
100
1k
FREQUENCY (Hz)
10k
100k
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
���������������������������������������������������������������� Maxim Integrated Products 13
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
-80
-20
-40
-60
-80
-40
-60
-80
-100
-100
-100
-120
-120
-120
-140
-140
8
10 12 14 16 18 20
-140
0
2
FREQUENCY (kHz)
4
6
8
10 12 14 16 18 20
0
2
FREQUENCY (kHz)
-40
-60
-80
BCLK = 3.072MHz
LRCLK = 48kHz
ZSPK = 8I + 68µH
0
-20
AMPLITUDE (dBV)
-20
8
10 12 14 16 18 20
INBAND OUTPUT SPECTRUM
20
MAX98355A/B toc33
BCLK = 3.072MHz
LRCLK = 48kHz
ZSPK = 8I + 68µH
0
6
FREQUENCY (kHz)
INBAND OUTPUT SPECTRUM
20
4
-40
-60
-80
-100
-100
-120
-120
-140
-140
0
2
4
6
8
10 12 14 16 18 20
0
2
4
6
FREQUENCY (kHz)
INBAND OUTPUT SPECTRUM
20
BCLK = 2.8224MHz
LRCLK = 44.1kHz
ZSPK = 8I + 68µH
0
10 12 14 16 18 20
INBAND OUTPUT SPECTRUM
20
-40
-60
-80
-20
-40
-60
-80
-100
-100
-120
-120
-140
BCLK = 2.8224MHz
LRCLK = 44.1kHz
ZSPK = 8I + 68µH
0
AMPLITUDE (dBV)
-20
8
FREQUENCY (kHz)
MAX98355A/B toc36
6
MAX98355A/B toc35
4
AMPLITUDE (dBV)
2
AMPLITUDE (dBV)
0
MAX98355A/B toc34
-60
BCLK = 5.6448MHz
LRCLK = 88.2kHz
ZSPK = 8I + 68µH
0
MAX98355A/B toc32
-20
20
AMPLITUDE (dBV)
-40
INBAND OUTPUT SPECTRUM
BCLK = 5.6448MHz
LRCLK = 88.2kHz
ZSPK = 8I + 68µH
0
AMPLITUDE (dBV)
-20
MAX98355A/B toc30
BCLK = 6.144MHz
LRCLK = 96kHz
ZSPK = 8I + 68µH
0
AMPLITUDE (dBV)
INBAND OUTPUT SPECTRUM
20
MAX98355A/B toc31
INBAND OUTPUT SPECTRUM
20
-140
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
���������������������������������������������������������������� Maxim Integrated Products 14
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VDD = 5V, VGND = 0V, GAIN = VDD (+6dB). BCLK = 3.072MHz, LRCLK = 48kHz, speaker loads (ZSPK) connected between OUTP
and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.)
INBAND OUTPUT SPECTRUM
-20
AMPLITUDE (dBV)
-40
-60
-80
-40
-60
-80
-100
-100
-120
-120
-140
-140
2
4
6
8
10 12 14 16 18 20
0
2
4
6
FREQUENCY (kHz)
INBAND OUTPUT SPECTRUM
fBCLK = 1.024MHz
fLRCLK = 16kHz
ZSPK = 8I + 68µH
0
-40
-60
-80
fBCLK = 1.024MHz
fLRCLK = 16kHz
ZSPK = 8I + 68µH
0
-20
AMPLITUDE (dBV)
AMPLITUDE (dBV)
-20
-40
-60
-80
-100
-100
-120
-120
-140
-140
0
2
4
6
8
10 12 14 16 18 20
0
2
4
6
FREQUENCY (kHz)
-40
-60
-80
-20
-40
-60
-80
-100
-100
-120
-120
-140
fBCLK = 512kHz
fLRCLK = 8kHz
ZSPK = 8I + 68µH
0
AMPLITUDE (dBV)
-20
10 12 14 16 18 20
INBAND OUTPUT SPECTRUM
20
MAX98355A-B toc41
fBCLK = 512kHz
fLRCLK = 8kHz
ZSPK = 8I + 68µH
0
8
FREQUENCY (kHz)
INBAND OUTPUT SPECTRUM
20
AMPLITUDE (dBV)
10 12 14 16 18 20
INBAND OUTPUT SPECTRUM
20
MAX98355A-B toc39
20
8
FREQUENCY (kHz)
MAX98355A-B toc40
0
MAX98355A-B toc42
AMPLITUDE (dBV)
-20
BCLK = 2.048MHz
LRCLK = 32kHz
ZSPK = 8I + 68µH
0
MAX98355A/B toc38
fBCLK = 2.048MHz
fLRCLK = 32kHz
ZSPK = 8I + 68µH
0
INBAND OUTPUT SPECTRUM
20
MAX98355A/B toc37
20
-140
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
���������������������������������������������������������������� Maxim Integrated Products 15
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Pin Configuration
TOP VIEW
BUMP SIDE DOWN
MAX98355A
MAX98355B
+
SD_MODE
VDD
OUTP
A1
A2
A3
DIN
GAIN
OUTN
B1
B2
B3
BCLK
GND
LRCLK
C1
C2
C3
WLP
Pin Description
PIN
NAME
A1
SD_MODE
A2
VDD
A3
OUTP
B1
DIN
FUNCTION
Shutdown and Channel Select. Determines left, right, or (left + right)/2 mix and also used for shutdown.
See Table 5.
Power-Supply Input
Positive Speaker Amplifier Output
Digital Input Signal
Amplifier Gain
B2
GAIN
Gain Connections
Gain (dB)
GND through 100kI resistor
15
GND
12
Unconnected
9
VDD
6
VDD through 100kI resistor
3
B3
OUTN
Negative Speaker Amplifier Output
C1
BCLK
Bit Clock Input Signal. BCLK must be 32, 48, or 64 x LRCLK. Valid frequency range: 256kHz–6.144MHz.
C2
GND
Ground
C3
LRCLK
Left/Right Word Clock Input. Valid frequency range: 8kHz–96kHz.
���������������������������������������������������������������� Maxim Integrated Products 16
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Detailed Description
The MAX98355A/MAX98355B are digital PCM input
Class D power amplifiers. The MAX98355A accepts
standard I2S data through DIN, BCLK, and LRCLK while
the MAX98355B accepts left justified data through the
same inputs. Both versions can accept 16-bit TDM data
with up to four slots. These devices eliminate the need
for an external MCLK signal that is typically required for
PCM data transmission.
SD_MODE selects which data word is output by the
amplifier and is used to put the IC into shutdown. The
GAIN pin offers five gain settings and allows the output of
the amplifier to be tuned to the appropriate level.
The output stage features low-quiescent current, comprehensive click-and-pop suppression, and excellent RF
immunity. The ICs offer Class AB audio performance with
Class D efficiency in a minimal board-space solution.
The Class D amplifier features spread-spectrum modulation with edge-rate and overshoot control circuitry that
offers significant improvements in 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.
Digital Audio Interface Modes
The input stage of the digital audio interface is highly
flexible, supporting 8kHz–96kHz sampling rates with
16/24/32-bit resolution for I2S/left justified data as well
as up to a 4-slot, 16-bit time division multiplexed (TDM)
format (only the first two slots can be selected by the
ICs). When LRCLK has a 50% duty cycle the data
format is determined by the part number selection
(MAX98355A/MAX98355B). When a frame sync pulse
is used for the LRCLK the data format is automatically
configured in TDM mode. The frame sync pulse indicates
the beginning of the first time slot.
MCLK Elimination
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 addition to reducing the size and pin-count of the ICs.
Jitter Tolerance
The ICs feature a very high BCLK and LRCLK jitter tolerance of 0.5ns for RMS jitter below 40kHz and 12ns for
wideband RMS jitter while maintaining a dynamic range
greater than 98dB (Table 1).
BCLK Polarity
When operating in I2S/left justified mode, incoming serial
data is always clocked-in on the rising edge of BCLK.
In TDM mode, the MAX98355A clocks-in serial data on
the rising edge of BCLK while the MAX98355B clocks in
serial data on the falling edge of BCLK (Table 2).
LRCLK Polarity
LRCLK specifies whether left-channel data or rightchannel data is currently being read by the digital audio
interface. The MAX98355A indicates the left channel
word when LRCLK is low, and the MAX98355B indicates
the left channel word when LRCLK is high (Table 3).
Table 1. RMS Jitter Tolerance
FREQUENCY
RMS JITTER TOLERANCE (ns)
< 40kHz
0.5
40kHz–BCLK
12
Table 2. BCLK Polarity
MODE
I2S/left
PART NUMBER
BCLK POLARITY
justified MAX98355A/MAX98355B
TDM
Rising edge
MAX98355A
Rising edge
MAX98355B
Falling edge
Table 3. LRCLK Polarity
PART NUMBER
LRCLK POLARITY (LEFT CHANNEL)
MAX98355A
Low
MAX98355B
High
���������������������������������������������������������������� Maxim Integrated Products 17
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
PCM Timing Characteristics
The MAX98355A follows standard I2S timing by allowing
a delay of one BCLK cycle after the LRCLK transition
before the beginning of a new data word (Figure 4 and
Figure 5). The MAX98355B follows the left justified timing
specification by aligning the LRCLK transitions with the
beginning of a new data word (Figure 6 and Figure 7).
Figure 8 and Figure 9 show TDM operation, in which a
frame-sync pulse is used for LRCLK. In TDM mode, there
must be 32, 48, or 64 BCLK cycles per LRCLK. In TDM
mode, the IC only accepts 16-bit formatted data and only
the first two TDM slots can be selected. However, if the
first 16 bits are selected (SD_MODE = logic-high), then the
bit-depth or number of channels has no effect as long as
there are 32, 48, or 64 BCLK cycles per LRCLK. All extra
bits in the frame are ignored (Figure 10 and Figure 11).
If the second 16 bits are selected (SD_MODE = logichigh through RSMALL), then the TDM data must be 16-bit
data and cannot include more than 4 channels (64 BCLK
cycles). TDM operation is available in both ICs.
I2S: 16-BIT DATA, 16 BITS/CHANNEL, SD_MODE = LOGIC-HIGH
RIGHT
LRLCK
LEFT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14
IGNORED
I2S: 16-BIT DATA, 16 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RSMALL
LRLCK
RIGHT
LEFT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14
IGNORED
IGNORED
I2S: 16-BIT DATA, 16 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RLARGE
LRLCK
RIGHT
LEFT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D15 D14
LEFT AND RIGHT AVERAGED
Figure 4. MAX98355A I2S Digital Audio Interface Timing, 16-Bit Resolution
���������������������������������������������������������������� Maxim Integrated Products 18
DIN
BCLK
LRLCK
LEFT
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
LEFT
IGNORED
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
I2S: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RLARGE
DIN
BCLK
LRLCK
LEFT
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
I2S: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RSMALL
DIN
BCLK
LRLCK
I2S: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = LOGIC-HIGH
LEFT AND RIGHT AVERAGED
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
RIGHT
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
RIGHT
IGNORED
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
RIGHT
D23 D22
IGNORED
D23 D22
D23 D22
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Figure 5. MAX98355A I2S Digital Audio Interface Timing, 24-Bit Resolution
���������������������������������������������������������������� Maxim Integrated Products 19
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
LEFT JUSTIFIED: 16-BIT DATA, SD_MODE = LOGIC-HIGH
LRCLK
RIGHT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0 D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0 D15 D14
D6
D5
D4
D3
D2
D1
D0 D15 D14
IGNORED
LEFT JUSTIFIED: 16-BIT DATA, SD_MODE = PULLUP THROUGH RSMALL
LRCLK
RIGHT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0 D15 D14 D13 D12 D11 D10 D9
D8
D7
IGNORED
IGNORED
LEFT JUSTIFIED: 16-BIT DATA, SD_MODE = PULLUP THROUGH RLARGE
LRCLK
RIGHT
LEFT
BCLK
DIN
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0 D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0 D15 D14
LEFT AND RIGHT AVERAGED
Figure 6. MAX98355B Left-Justified Digital Audio Interface Timing, 16-Bit Resolution
���������������������������������������������������������������� Maxim Integrated Products 20
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
LEFT
IGNORED
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
LEFT
DIN
BCLK
LRCLK
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
LEFT
LEFT JUSTIFIED: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RLARGE
DIN
BCLK
LRCLK
LEFT JUSTIFIED: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = PULLUP THROUGH RSMALL
DIN
BCLK
LRCLK
LEFT JUSTIFIED: 24-BIT DATA, 32 BITS/CHANNEL, SD_MODE = LOGIC-HIGH
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8
D7 D6 D5 D4 D3 D2 D1 D0
RIGHT
D7 D6 D5 D4 D3 D2 D1 D0
RIGHT
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8
LEFT AND RIGHT AVERAGED
D7 D6 D5 D4 D3 D2 D1 D0
IGNORED
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8
RIGHT
D22 D23
LEFT
IGNORED
D23 D22
LEFT
D31 D30 D29
LEFT
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Figure 7. MAX98355B Left-Justified Digital Audio Interface Timing, 24-Bit Resolution
���������������������������������������������������������������� Maxim Integrated Products 21
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = LOGIC-HIGH
R1
R0 L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
IGNORED
R8
R7
R6
R5
R4
R3
R2
R1
R0 L15 L14 L13
R6
R5
R4
R3
R2
R1
R0 L15 L14 L13
IGNORED
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = PULLUP THROUGH RSMALL
R1
R0 L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
R8
R7
IGNORED
IGNORED
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = PULLUP THROUGH RLARGE
L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
LEFT AND RIGHT AVERAGED
Figure 8. MAX98355A TDM Digital Audio Interface Timing
���������������������������������������������������������������� Maxim Integrated Products 22
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = LOGIC-HIGH
R1
R0 L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
IGNORED
R8
R7
R6
R5
R4
R3
R2
R1
R0 L15 L14 L13
R6
R5
R4
R3
R2
R1
R0 L15 L14 L13
IGNORED
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = PULLUP THROUGH RSMALL
R1
R0 L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
R8
R7
IGNORED
IGNORED
TDM: 16-BIT DATA, 32-BIT FRAME, SD_MODE = PULLUP THROUGH RLARGE
L15 L14 L13 L12 L11 L10 L9
L8
L7
L6
L5
L4
L3
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
R8
R7
R6
R5
R4
R3
R2
R1
R0
LEFT AND RIGHT AVERAGED
Figure 9. MAX98355B TDM Digital Audio Interface Timing
���������������������������������������������������������������� Maxim Integrated Products 23
Y0 L15 L14 L13 L12 L11 L10 L9
IGNORED
Y1
L8
L7
L6
L5
L4
L3
L2
Y1
L8
IGNORED
Y0 L15 L14 L13 L12 L11 L10 L9
L7
L6
L5
L4
L3
L2
DIN
BCLK
LRCLK
Y0 L15 L14 L13 L12 L11 L10 L9
IGNORED
Y1
L8
L7
L6
L5
L3
L2
L1
L1
L1
L0 R15 R14 R13 R12 R11 R10 R9
L0 R15 R14 R13 R12 R11 R10 R9
L0 R15 R14 R13 R12 R11 R10 R9
LEFT AND RIGHT AVERAGED
L4
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = PULLUP THROUGH RLARGE
DIN
BCLK
LRCLK
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = PULLUP THROUGH RSMALL
DIN
BCLK
LRCLK
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = LOGIC-HIGH
R8
R8
R8
R7
R7
R7
R6
R6
R6
R5
R5
R5
R4
R4
R4
R3
R3
R3
R2
R2
R2
R1
R1
R1
R0 X15 X14 X13 X12 X11 X10 X9
R0 X15 X14 X13 X12 X11 X10 X9
R0 X15 X14 X13 X12 X11 X10 X9
X7
X8
X8
X7
X7
IGNORED
X8
X6
X6
X6
X5
X5
X5
X4
X4
X4
X3
X3
X3
X2
X2
X2
X1
X1
X1
IGNORED
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
IGNORED
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
Y8
Y8
Y8
Y7
Y7
Y7
Y6
Y6
Y6
Y5
Y5
Y5
Y4
Y4
Y4
Y3
Y3
Y3
Y2
Y2
Y2
Y1
Y1
Y1
Y0 L15 L14
Y0 L15 L14
Y0 L15 L14
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Figure 10. MAX98355A TDM Digital Audio Interface Timing, Example of Four 16-Bit Slots
���������������������������������������������������������������� Maxim Integrated Products 24
Y1
Y0 L15 L14 L13 L12 L11 L10 L9
IGNORED
L8
L7
L6
L5
L4
L3
L2
L1
Y1
L8
IGNORED
Y0 L15 L14 L13 L12 L11 L10 L9
L7
L6
L5
L4
L3
L2
L1
DIN
BCLK
LRCLK
Y0 L15 L14 L13 L12 L11 L10 L9
IGNORED
Y1
L8
L7
L6
L5
L4
L2
L1
L0 R15 R14 R13 R12 R11 R10 R9
L0 R15 R14 R13 R12 R11 R10 R9
L0 R15 R14 R13 R12 R11 R10 R9
LEFT AND RIGHT AVERAGED
L3
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = PULLUP THROUGH RLARGE
DIN
BCLK
LRCLK
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = PULLUP THROUGH RSMALL
DIN
BCLK
LRCLK
TDM: 64-BIT DATA, 64-BIT FRAME, SD_MODE = LOGIC-HIGH
R8
R8
R8
R7
R7
R7
R6
R6
R6
R5
R5
R5
R4
R4
R4
R3
R3
R3
R2
R2
R2
R1 R0 X15 X14 X13 X12 X11 X10 X9
R1 R0 X15 X14 X13 X12 X11 X10 X9
R1 R0 X15 X14 X13 X12 X11 X10 X9
X8
X7
X8
X8
X7
X7
IGNORED
X6
X6
X6
X5
X5
X5
X4 X3
X4 X3
X4 X3
X2
X2
X2
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
X1
IGNORED
X0 Y15 Y14 Y13 Y12 Y11 Y10 Y9
IGNORED
X1
X1
Y8
Y8
Y8
Y7
Y7
Y7
Y6
Y6
Y6
Y5
Y5
Y5
Y4
Y4
Y4
Y3
Y3
Y3
Y2
Y2
Y2
Y1
Y1
Y1
Y0 L15 L14
Y0 L15 L14
Y0 L15 L14
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Figure 11. MAX98355B TDM Digital Audio Interface Timing, Example of Four 16-Bit Slots
���������������������������������������������������������������� Maxim Integrated Products 25
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
SD_MODE and Shutdown Operation
Standby Mode
If BCLK stops toggling, the ICs automatically enter
standby mode. In standby mode, the Class D speaker
is turned off and the outputs go into a high-impedance
state, ensuring that unwanted current is not transferred to
the load during this condition. Standby mode should not
be used in place of the shutdown mode, as the shutdown
mode provides the lowest power consumption and the
best power-on/off click-and-pop performance.
The ICs feature a low-power shutdown mode, drawing
less than 0.6FA (typ) of supply current. During shutdown,
all internal blocks are turned off, including setting the
output stage to a high-impedance state. Drive SD_MODE
low to put the ICs into shutdown.
The state of SD_MODE determines the audio channel
that is sent to the amplifier output (Table 5).
Drive SD_MODE high to select the left word of the stereo
input data. Drive SD_MODE high through a sufficiently
small resistor to select the right word of the stereo input
data. Drive SD_MODE high through a sufficiently large
resistor to select both the left and right words of the
stereo input data ((left + right)/2). RLARGE and RSMALL
are determined by the VDDIO voltage (logic voltage from
control interface) that is driving SD_MODE according to
the following two equations:
DAC Digital Filters
The DAC features a digital lowpass filter that is automatically configured for voice playback or music playback
based on the sample rate that is used. This filter eliminates the effect of aliasing and any other high-frequency
noise that might otherwise be present. Table 4 shows the
digital filter settings that are automatically selected.
RSMALL (kI) = 98.5 x VDDIO - 100
RLARGE (kI) = 222.2 x VDDIO - 100
Table 4. Digital Filter Settings
LRCLK FREQUENCY
-3dB CUTOFF
FREQUENCY
RIPPLE LIMIT CUTOFF
FREQUENCY
STOPBAND CUTOFF
FREQUENCY
STOPBAND
ATTENUATION (dB)
fLRCLK < 30kHz
0.446 x fLRCLK
0.443 x fLRCLK
0.464 x fLRCLK
75
30kHz < fLRCLK < 50kHz
0.47 x fLRCLK
0.43 x fLRCLK
0.58 x fLRCLK
60
fLRCLK > 50kHz
0.31 x fLRCLK
0.24 x fLRCLK
0.477 x fLRCLK
60
Table 5. SD_MODE Control
SELECTED CHANNEL
SD_MODE STATUS
High
VSD_MODE > B2 trip point (1.4V typ)
Left
Pullup through RSMALL
B2 trip point (1.4V typ) > VSD_MODE >
B1 trip point (0.77V typ)
Right
Pullup through RLARGE
B1 trip point (0.77 typ) > VSD_MODE >
B0 trip point (0.16V typ)
(Left + right)/2
Low
B0 trip point (0.16V typ) > VSD_MODE
Shutdown
Table 6. Examples of SD_MODE Pullup Resistor Values
LOGIC VOLTAGE LEVEL (VDDIO) (V)
RSMALL (kI, 1% TOLERANCE)
RLARGE (kI, 1% TOLERANCE)
1.8
76.8
300
3.3
226
634
���������������������������������������������������������������� Maxim Integrated Products 26
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
When the devices are configured in left-channel mode
(SD_MODE is directly driven to logic-high by the control interface), take care to avoid violating the Absolute
Maximum Ratings limits for SD_MODE. Ensuring that
VDD is always greater than VDDIO is one way to prevent
SD_MODE from violating the Absolute Maximum Ratings
limits. If this is not possible in the application (e.g., if VDD
< 3.0V and VDDIO = 3.3V, then it is necessary to add a
small resistance (~2kI) in series with SD_MODE to limit
the current into the SD_MODE pin. This is not a concern
when using the right channel or (left + right)/2 modes.
Figure 12 and Figure 13 show how to connect an external
resistor to SD_MODE when using an open-drain driver or
a pullup/down driver.
PROCESSOR
VDDIO
R
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
spread-spectrum modulation reduces EMI emissions
while maintaining up to 92% efficiency.
LEFT MODE
MAX98355A
MAX98355B
VSD_MODE
GPIO
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.
B2 (1.4V typ)
RIGHT MODE
100kI
±8%
B1 (0.77V typ)
(LEFT + RIGHT)/2
MODE
B0 (0.16V typ)
Figure 12. SD_MODE Resistor Connection Using Open-Drain Driver
PROCESSOR
MAX98355A
MAX98355B
VDDIO
GPIO
R
VSD_MODE
LEFT MODE
B2 (1.4V typ)
RIGHT MODE
100kI
±8%
B1 (0.77V typ)
(LEFT + RIGHT/2
MODE
B0 (0.16V typ)
Figure 13. SD_MODE Resistor Connection Using Pullup/Down Driver
���������������������������������������������������������������� Maxim Integrated Products 27
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
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 ICs’ 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 14).
Speaker Current Limit
If the output current of the speaker amplifier exceeds the
current limit (2.8A typ), the IC disables the outputs for
approximately 100Fs. At the end of the 100Fs, the outputs are re-enabled. If the fault condition still exists, the
IC continues to disable and re-enable the outputs until
the fault condition is removed.
Gain Selection
The ICs offer five programmable gain selections through
a single gain input (GAIN). Gain is referenced to the
Output signal level (dBV) = input signal level (dBFS) +
2.1dB + selected amplifier gain (dB)
where 0dBFS is referenced to 0dBV.
Click-and-Pop Suppression
The IC speaker amplifier features Maxim’s comprehensive click-and-pop suppression. During startup, the clickand-pop suppression circuitry reduces audible transient
sources internal to the device by ramping the input signal
from mute to 0dB. When entering shutdown, the differential speaker outputs immediately go into a high-impedance state without creating audible click-and-pop noise.
Table 7. Gain Selection
90
EMISSIONS LEVEL (dBµV/m)
full-scale output of the DAC, which is 2.1dBV (Table 7).
Assuming that the desired output swing is not limited by
the supply voltage rail, the IC’s output level can be calculated based on the digital input signal level and selected
amplifier gain according to the following equation:
70
50
30
10
GAIN
GAIN (dB)
Connect to GND through
100kI Q5% resistor
15
Connect to GND
12
Unconnected
9
Connect to VDD
6
Connect to VDD through
100kI Q5% resistor
3
-10
0 100 200 300 400 500 600 700 800 900 1000
FREQUENCY (MHz)
Figure 14. EMI with 12in of Speaker Cable and No Output
Filtering
���������������������������������������������������������������� Maxim Integrated Products 28
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Applications Information
2.5V TO 5.5V
2.5V TO 5.5V
10µF
0.1µF
SD_MODE
GAIN
B2
CODEC
GPIO*
BIT CLOCK
FRAME CLOCK
DATA OUT
BCLK
LRCLK
DIN
A1
C3
B1
0.1µF
SD_MODE
GAIN
B2
CODEC
VDD
A2
A3
C1
10µF
GPIO*
OUTP
BCLK
BIT CLOCK
MAX98355A
MAX98355B
B3
OUTN
FRAME CLOCK
LRCLK
DIN
DATA OUT
C2
GND
A1
VDD
A2
A3
C1
C3
B1
MAX98355A
MAX98355B
B3
OUTP
OUTN
C2
GND
*RESPONDS TO LEFT CHANNEL WHEN GPIO IS HIGH.
THE MAX98355A/MAX98355B IS SHUTDOWN WHEN GPIO IS LOW.
*RESPONDS TO LEFT CHANNEL WHEN GPIO IS HIGH.
THE MAX98355A/MAX98355B IS SHUTDOWN WHEN GPIO IS LOW.
Figure 15. Left-Channel PCM Operation with 6dB Gain
Figure 16. Left-Channel PCM Operation with 12dB Gain
2.5V TO 5.5V
10µF
CODEC
GPIO*
BIT CLOCK
FRAME CLOCK
DATA OUT
RSMALL
(76.8kI)**
0.1µF
VDD
GAIN
SD_MODE
BCLK
LRCLK
DIN
A1
B2
A2
A3
C1
C3
B1
MAX98355A
MAX98355B
B3
OUTP
OUTN
C2
GND
*RESPONDS TO RIGHT CHANNEL WHEN GPIO IS HIGH.
**76.8kI ASSUMES VGPIO = 1.8V.
THE MAX98355A/MAX98355B ARE SHUTDOWN WHEN GPIO IS LOW.
Figure 17. Right-Channel PCM Operation with 6dB Gain
���������������������������������������������������������������� Maxim Integrated Products 29
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
2.5V TO 5.5V
10µF
0.1µF
VDD
GAIN
SD_MODE
BCLK
LRCLK
DIN
A1
B2
A2
A3
C1
C3
MAX98355A
MAX98355B
B3
B1
OUTP
OUTN
C2
GND
CODEC
*RESPONDS TO LEFT CHANNEL WHEN GPIO IS HIGH.
THE MAX98355A/MAX98355B IS SHUTDOWN WHEN GPIO IS LOW.
GPIO*
BIT CLOCK
2.5V TO 5.5V
FRAME CLOCK
10µF
DATA OUT
RSMALL
(76.8kI)**
0.1µF
VDD
GAIN
SD_MODE
BCLK
LRCLK
DIN
A1
C1
C3
B1
B2
A2
A3 OUTP
MAX98355A
MAX98355B
B3
OUTN
C2
GND
*RESPONDS TO RIGHT CHANNEL WHEN GPIO IS HIGH.
**76.8kI ASSUMES VGPIO = 1.8V.
THE MAX98355A/MAX98355B IS SHUTDOWN WHEN GPIO IS LOW.
Figure 18. Stereo PCM Operation Using Two ICs
���������������������������������������������������������������� Maxim Integrated Products 30
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Filterless Class D Operation
Traditional Class D amplifiers require an output filter
to recover the audio signal from the amplifier’s output.
The filter adds cost, size, and decreases efficiency
and THD+N performance. The ICs’ filterless modulation
scheme does not require an output filter. The device relies
on the inherent inductance of the speaker coil and the
natural filtering of both the speaker and the human ear to
recover the audio component of the square-wave output.
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 > 10FH. Typical
8I speakers exhibit series inductances in the 20FH to
100FH range.
Power-Supply Input
VDD, which ranges from 2.5V to 5.5V, powers the IC,
including the speaker amplifier. Bypass VDD with a 0.1FF
and 10FF capacitor to GND. Some applications might
require only the 10FF bypass capacitor, making it possible to operate with a single external component. Apply
additional bulk capacitance at the ICs if long input traces
between VDD and the power source are used.
2.5V TO 5.5V
10µF
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 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 speaker
output to a 4I load through 100mI of total speaker
trace, 1.904W is being delivered to the speaker. If power
is delivered through 10mI of total speaker trace, 1.951W
is being delivered to the speaker. Wide output, supply,
and ground traces also improve the power dissipation of
the ICs.
The ICs are 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 the Application Note 1891: Wafer-Level
Packaging (WLP) and Its Applications. Figure 20 shows
the dimensions of the WLP balls used on the ICs.
0.1µF
0.24mm
CODEC
GPIO*
BIT CLOCK
FRAME CLOCK
DATA OUT
RLARGE
(300kI)**
SD_MODE
BCLK
LRCLK
DIN
A1
C1
C3
B1
VDD
GAIN
B2
A2
A3
MAX98355A
MAX98355B
B3
OUTP
OUTN
C2
GND
*LEFT AND RIGHT CHANNELS SUMMED WHEN GPIO IS HIGH.
**300kI ASSUMES VGPIO = 1.8V.
THE MAX98355A/MAX98355B IS SHUTDOWN WHEN GPIO IS LOW.
Figure 19. (Left + Right)/2 PCM Operation with 6dB Gain
0.21mm
Figure 20. MAX98355A/MAX98355B WLP Ball Dimensions
���������������������������������������������������������������� Maxim Integrated Products 31
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Functional Diagram
2.5V TO 5.5V
10µF
0.1µF
VDD
GAIN
A2
MAX98355A
MAX98355B
LRCLK C3
BCLK C1
DIN B1
SD_MODE A1
DIGITAL
AUDIO
INTERFACE
B2
INTERPOLATOR
DAC
CLASS D
OUTPUT
STAGE
A3 OUTP
B3 OUTN
C2
GND
Ordering Information
PART
MAX98355AEWL+
MAX98355BEWL+
TEMP RANGE
PIN-PACKAGE
-40NC to +85NC
-40NC to +85NC
9 WLP
9 WLP
+Denotes a lead(Pb)-free/RoHS-compliant package.
���������������������������������������������������������������� Maxim Integrated Products 32
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Package Information
For the latest package outline information and land patterns (footprints), 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.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
9 WLP
W91F1+1
21-0459
Refer to Application Note 1891
E
PIN 1
INDICATOR
MARKING
COMMON DIMENSIONS
A3
A1
1
AAAA
A
D
A2
0.05
0.19
0.03
0.45 REF
0.025 BASIC
A3
See Note 7
SIDE VIEW
TOP VIEW
0.64
A1
A2
A
0.05 S
S
A
E1
b
0.27
D1
0.80
E1
0.80
e
0.40 BASIC
SD
0.00 BASIC
SE
0.00 BASIC
0.03
SE
e
B
C
E
SD
B
D1
A
1
2
3
A
D
DEPOPULATED
BUMPS
PKG. CODE
MIN
MAX
MIN
MAX
W91B1+7
1.22
1.30
1.22
1.30
W91C1+1
1.56
1.63
1.38
1.45
NONE
W91F1+1
1.42
1.45
1.33
1.36
NONE
W91G1+1
1.45
1.48
1.44
1.47
NONE
NONE
b
0.05 M
S
AB
BOTTOM VIEW
NOTES:
1. Terminal pitch is defined by terminal center to center value.
2. Outer dimension is defined by center lines between scribe lines.
3. All dimensions in millimeter.
4. Marking shown is for package orientation reference only.
5. Tolerance is ± 0.02 unless specified otherwise.
6. All dimensions apply to PbFree (+) package codes only.
7. Front - side finish can be either Black or Clear.
- DRAWING NOT TO SCALE -
TITLE
APPROVAL
PACKAGE OUTLINE
9 BUMPS, WLP PKG. 0.4mm PITCH
DOCUMENT CONTROL NO.
21-0459
REV.
D
1
1
���������������������������������������������������������������� Maxim Integrated Products 33
MAX98355A/MAX98355B
PCM Input Class D Audio Power Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE
0
5/12
DESCRIPTION
Initial release
PAGES
CHANGED
—
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. 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 Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2012
Maxim Integrated Products 34
Maxim is a registered trademark of Maxim Integrated Products, Inc.