General Description
The MAX98355 evaluation kit (EV kit) is a fully assem-
bled and tested PCB that evaluates the MAX98355 PCM
digital input Class D power amplifier. The EV kit operates
from a single 2.5V to 5.5V DC power supply and is capa-
ble of delivering 3.2W into a 4I load. The device outputs
can be connected directly to a speaker load for filterless
applications. However, a filter can be added to ease eval-
uation. The MAX98355A accepts standard I2S data and
the MAX98355B accepts left-justified digital audio data.
Both ICs support time-division multiplexed (TDM) data.
Features
S 2.5V to 5.5V Single-Supply Operation
S
Only a Single External Component (VDD Capacitor)
Required in Many Applications
S I2S, Left-Justified, or TDM Input
S Five Selectable Gains (3db, 6dB, 9dB, 12dB,
and 15dB)
S No MCLK Required
S Sample Rates of 8kHz to 96kHz
S Audio Channel Select (Left, Right, or
(Left + Right)/2)
S Filterless Class D Outputs
S Optional Class D Output Filters for Ease of
Evaluation
S Low-Power Shutdown Mode
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 Proven PCB Layout
S Fully Assembled and Tested
USB AUDIO
INPUT XMOS
LRCLK
BCLK
DIN
SD_MODE
C3
C1
B1
A1
DIGITAL
AUDIO
INTERFACE
0.1µF
2.5V TO 5.5V
A2
C2
B2
10µF
GAIN
GND
V
DD
DAC CLASS D OUTPUT
STAGE
OUTP
OUTN
A3
B3
MAX98355A
MAX98355B
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
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.
19-6407; Rev 0; 7/12
Ordering Information appears at end of data sheet.
Figure 1. Simplified Block Diagram
DESIGNATION QTY DESCRIPTION
BCLK, LRCLK,
SDIN, USB5V,
XMCLK
0Not installed, test points
C1 1
10FF Q10%, 6.3V X5R
ceramic capacitor (0603)
Murata GRM188R60J106K
C2, C201, C202,
C203, C218,
C219, C220,
C222,
C225–C228,
C231–C234
16
0.1FF Q10%, 16V X7R
ceramic capacitors (0402)
Murata GRM155R71C104K
C3–C9, C73, C74,
C75 0Not installed, ceramic
capacitors (0402)
C200, C204,
C205 3
1FF Q10%, 6.3V X5R ceramic
capacitors (0402)
TDK C1005X5R0J105K
C206, C235,
C236 3
0.01FF Q10%, 50V X7R
ceramic capacitors (0603)
Murata GRM188R71H103K
C207, C208,
C213 3
1FF Q20%, 6.3V X5R ceramic
capacitors (0603)
Taiyo Yuden
JMK107B7105MA
C209, C210 2
2.2FF Q10%, 6.3V X5R
ceramic capacitors (0603)
Murata GRM188R60J225K
C212 1
1000pF Q10%, 50V X7R
ceramic capacitor (0603)
Murata GRM188R71H102K
C214–C217 4
33pF Q5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H330J
C221 1
330pF Q5%, 50V C0G
ceramic capacitor (0603)
Murata GRM1885C1H331J
C223, C224 2
4.7FF Q10%, 10V X5R
ceramic capacitors (0805)
Murata GRM219R61A475K
C229, C230 2
4.7FF Q10%, 6.3V X5R
ceramic capacitors (0603)
Murata GRM188R60J475K
D200 1 Red LED (0603)
FB1, FB2 2 0I Q5% resistors (0603)
FB200, FB201 2Ferrite beads (0603)
Murata BLM18KG331SN1
DESIGNATION QTY DESCRIPTION
FOUTN, FOUTP,
GND, VDD 4Binding posts
FOUTN, FOUTP,
GND (x3), VDD,
+3.3V
7
20G plated solid copper bus
wire, 0.25in U-shaped wire
loop
GND (x3), OUTN 4Black multipurpose test points
(63mil drill size)
J1 1 USB mini-AB receptacle
J200 1
20-pin (2 x 10) IDC right-
angle, polarized boxed
header, 0.1in centers
JU1 1 5-pin header
JU2 1 4-pin header
JU3 1 9-pin (3 x 3) header
JU4 1 2-pin header
JU5 1 3-pin header
L1, L2 0
Not installed, 22FH inductors
(6.2mm x 6.3mm)—short (PC
trace)
TOKO D63CB series part
TOKO A916CY-220M
L201 1
3.3FH, 1.1A power inductor
Sumida
CDRH3D16NP-3R3NC
LEDA, LEDB 2Green LEDs (0603)
OUTP 1 Red multipurpose test point
(63mil drill size)
Q200, Q201,
Q202 3
n-channel enhancement-
mode FETs (SOT23)
Fairchild BSS138
R1, R2 2 100kI Q5% resistors (0603)
R3 1 226kI Q1% resistor (0603)
R4 1 634kI Q1% resistor (0603)
R5, R6 0Not installed, resistors (0402)
R7, R8, R9 3 0I Q5% resistors (0402)
R10 1 2kI Q1% resistor (0603)
R200 1 27kI Q5% resistor (0603)
R201 1 100kI Q5% resistor (0603)
R203, R204,
R207, R210,
R217, R220
6 10kI Q5% resistors (0603)
R205, R213 247kI Q5% resistors (0603)
R206 1 4.7I Q5% resistor (0603)
R208 1 20kI Q5% resistor (0603)
R209 0 Not installed, resistor (0603)
R211 1 8.06kI Q1% resistor (0603)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
2
Component List
DESIGNATION QTY DESCRIPTION
R212, R219,
R233, R234 4 1kI Q5% resistors (0603)
R218, R221 2 2.2MI Q5% resistors (0603)
R222 1 470I Q5% resistor (0603)
R223, R224 2 33I Q5% resistors (0603)
U1 1
I2S input Class D audio
amplifier (9 WLP)
Maxim MAX98355AEWL+
U200 1 XMOS processor (128 TQFP)
U201 1 SPI 1Mb flash memory
(8 SO)
U202 1 USB 2.0 transceiver, ULPI
(24 QFN)
U203 1
3.3V low-noise linear regulator
(5 SOT23)
Maxim MAX8887EZK33+T
U204 1
1.8V low-noise linear regulator
(5 SC70)
Maxim MAX8511EXK18+
U205 1 Voltage detector (5 SOT23)
U206 1
TinyLogic UHS dual buffer
(6 SC70)
Fairchild NC7WZ07P6X
DESIGNATION QTY DESCRIPTION
U208 1
Dual, unbuffered inverter
(6 SC70)
Fairchild NC7WZU04P6X
U209 1 2-input multiplexer (6 SC70)
Fairchild NC7SZ157P6X
U210 1 Dual logic buffer (6 SC70)
Fairchild NC7WZ17P6X
U211 1
Microprocessor-reset circuit
(3 SC70)
Maxim MAX803TEXR+
U212 1
1A step-down regulator
(10 FMAXM)
Maxim MAX1974EUB+
Y1 1 13MHz clock oscillator
(2.5mm x 2.0mm)
Y200 1 24.576MHz crystal
(6.0mm x 3.3mm)
Y201 1 11.2896MHz crystal
(6.0mm x 3.3mm)
— 4 Shunts
— 1 PCB: MAX98355
EVALUATION KIT
DESIGNATION QTY DESCRIPTION
C3–C7 5
0.22FF Q10%, 6.3V XR5
ceramic capacitors (0402)
TDK C1005X5R0J224K
DESIGNATION QTY DESCRIPTION
L1, L2 2
22FH, 1A inductors
(6.2mm x 6.3mm)
TOKO A916CY-220M
R5, R6 222I Q5% resistors (0402)
SUPPLIER PHONE WEBSITE
Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Sumida Corp. 847-545-6700 www.sumida.com
Taiyo Yuden 800-348-2496 www.t-yuden.com
TDK Corp. 847-803-6100 www.component.tdk.com
TOKO America, Inc. 847-297-0070 www.tokoam.com
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
3
Component List (continued)
Optional Components
Component Suppliers
µMAX is a registered trademark of Maxim Integrated Products,
Inc.
Note: Indicate that you are using the MAX98355 when contacting these component suppliers.
SHUNT POSITION GAIN PIN
GAIN (dB)
RELATIVE TO A 2.1dBV
REFERENCE LEVEL
1-2 Connected to VDD through 100kI resistor R1 3
1-3 Connected to VDD 6
1-4 Connected to GND through 100kI resistor R2 15
1-5* Connected to GND 12
Not installed Unconnected 9
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
4
Quick Start
Recommended Equipment
• MAX98355EVkit
• 2.5Vto5.5V,2ADCpowersupply
• USBaudiosource(from computerthrough anaudio
media player such as iTunes
M
or Windows
M
Media
Player)
• USBcable(includedintheEVkitbox)
• 4I to 8I speaker
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation. Caution: Do not turn on
the power supply until all necessary connections are
completed.
1) Verify that shunts are installed as follows:
JU1: Pins 1-5 (12dB gain)
JU2: Pins 1-3 (left audio channel selected)
JU3: Pins 2-3 (I2S input from XMOS, MAX98355A only)
JU4: Installed (VDDIO supplied from on-board
power supply
JU5: Pins 2-3 (device in shutdown mode)
2) Set the power-supply output to 5V. Disable the power
supply.
3) Connect the power-supply ground terminal to the
GND PCB pad and the power-supply positive terminal
to the VDD PCB pad on the EV kit.
4) Connect the speaker across the OUTP and OUTN test
points.
5) Enable the power-supply output.
6) With the audio source disabled, connect the USB
audio source to J1 on the EV kit. Change the shunt on
JU5 to pins 1-2 (device enabled for normal operation).
7) Enable the audio source.
8) Verify that the speakers are playing the audio source
signal.
Detailed Description of Hardware
Filterless Output
The MAX98355 EV kit’s filterless outputs (OUTP, OUTN)
can be connected directly to a speaker load without any
filtering. Use the OUTP and OUTN test points to connect
the speaker directly to the device output.
Filtered Output
Audio analyzers typically cannot accept the Class D
amplifier’s pulse-width modulated (PWM) signals at their
inputs. Therefore, the EV kit features optional lowpass
filters at the outputs to ease evaluation. As shipped, the
EV kit’s lowpass filter RC components are unpopulated
and L1, L2 are shorted on the PCB.
To use the filtered output posts (FOUTP, FOUTN), remove
the shorts on L1 and L2 and install components L1, L2,
C3–C7, and R5, R6 (provided separately with the EV kit).
Use the output posts to connect the filtered outputs to
the audio analyzer. The default lowpass filters at the EV
kit output are optimized for a 4I speaker.
Jumper Selection
Selectable Gain (GAIN)
The EV kit features a 5-pin jumper (JU1) to control the
device’s five programmable gain settings. See Table 1
for gain-control configuration.
SD_MODE Input
The EV kit features a 4-pin jumper (JU2) to control the
audio channel that is sent to the amplifier output and a
3-pin jumper (JU5) to enable/disable the IC. JU2 is used
to select the stereo input (left channel, right channel, or the
average of the left/right channels). JU5 must be set to pins
1-2 for normal operation. See Table 2 for shunt positions.
Shutdown Mode
The device features a low-power shutdown mode that is
activated by setting jumper JU5 to pins 2-3. To exit shut-
down mode, set JU5 to pins 1-2 and select the desired
stereo input channel using jumper JU2. See Table 3 for
shunt positions.
Table 1. JU1 Jumper Selection (GAIN)
*Default position.
iTunes is a registered trademark of Apple Inc.
Windows is a registered trademark and registered service mark of Microsoft Corp.
SHUNT POSITION SD_MODE PIN DEVICE OPERATION
JU2 JU5
1-2 1-2* Connected to VDDIO through R3 (226kI resistor) Right audio channel selected
1-3* 1-2* Connected to VDDIO Left audio channel selected
1-4 1-2* Connected to VDDIO through R4 (634kI resistor) Mono mix
(left + right)/2
X 2-3 Connected to GND Shutdown
SHUNT POSITION BCLK, LRCLK, DIN DEVICE OPERATION
2-3* Connected to XMOS XMOS IC provides I2S input data to the MAX98355A.
Not installed Unconnected
Use this configuration when connecting an external digital audio source to the
MAX98355A or when evaluating the MAX98355B.
Connect external BCLK/LRCLK/DIN to column 2 and GND to column 1.
SHUNT POSITION LOGIC VOLTAGE (VDDIO)
Installed* 3.3V supplied from on-board power supply.
Not installed User-supplied external power supply applied at the +3.3V PCB pad.
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
5
External/Internal VDDIO (+3.3V)
On the EV kit, a logic voltage from a control interface is
needed for proper selection of the stereo input channel
through SD_MODE. This voltage can be applied exter-
nally at the +3.3V PCB pad or it can be provided from
on-board circuitry. See Table 4 for shunt positions.
If the USB cable is disconnected (such as when the
XMOS chip is not in use), the on-board circuitry to gener-
ate the +3.3V is not available. In this case, remove the
shunt from jumper JU4 and supply an external voltage at
the +3.3V PCB pad. Logic voltages other than +3.3V can
be used on the EV kit. If other logic voltages are used,
resistors R3 and R4 must be adjusted. See the SD_MODE
and Shutdown Operation section in the MAX98355A/
MAX98355B IC data sheet for more information.
Driving I2S Directly
The EV kit provides an on-board XMOS chip to gener-
ate the I2S signal from the USB audio source. To utilize
the XMOS chip, all positions of jumper JU3 must be set
betweens pins 2-3. To bypass the XMOS and drive the
digital audio interface directly, remove the shunts from
JU3 and apply signals at the BCLK, LRCLK, and SDIN
test points or between JU3 pins 1-2 at the appropri-
ate locations (pin 1 is signal ground). The XMOS chip
is configured for I2S output so it cannot be used with
the MAX98355B (left-justified data). To evaluate the
MAX98355B with left-justified data or the MAX98355A/
MAX98355B with TDM data, use the external data input
option by removing the shunts from JU3 pins 2-3 and
drive the digital audio interface directly.
Table 2. JU2 and JU5 Jumper Selection (SD_MODE)
Table 3. JU3 Jumper Selection (Digital Audio Interface)
Table 4. JU4 Jumper Selection (VDDIO)
*Default position.
X = Don’t care.
*Default position.
*Default position.
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
6
Figure 2a. MAX98355 EV Kit Schematic (Sheet 1 of 6)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
7
Figure 2b. MAX98355 EV Kit Schematic (Sheet 2 of 6)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
8
Figure 2c. MAX98355 EV Kit Schematic (Sheet 3 of 6)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
9
Figure 2d. MAX98355 EV Kit Schematic (Sheet 4 of 6)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
10
Figure 2e. MAX98355 EV Kit Schematic (Sheet 5 of 6)
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
11
Figure 2f. MAX98355 EV Kit Schematic (Sheet 6 of 6)
1.0”
1.0”
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
12
Figure 3. MAX98355 EV Kit Component Placement Guide—Component Side
Figure 4. MAX98355 EV Kit PCB Layout—Component Side
1.0”
1.0”
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
13
Figure 5. MAX98355 EV Kit PCB Layout—Layer 2
Figure 6. MAX98355 EV Kit PCB Layout—Layer 3
1.0”
1.0”
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
14
Figure 7. MAX98355 EV Kit PCB Layout—Solder Side
Figure 8. MAX98355 EV Kit Component Placement Guide—Solder Side
PART TYPE
MAX98355EVKIT# EV Kit
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
15
Ordering Information
#Denotes RoHS compliant.
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 7/12 Initial release —
MAX98355 Evaluation Kit
Evaluates: MAX98355A/MAX98355B
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, Inc. 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 16
© 2012 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History