MAX98357EVSYS#WLP - Maxim Integrated

Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

19-6833; Rev 2; 9/18

Ordering Information appears at end of data sheet.

General Description

The MAX98357 development board (DEV board) is a fully

assembled and tested PCB that evaluates the MAX98357

I2S digital input Class D power amplifier. The DEV board

operates from a single 2.5V to 5.5V DC power supply and

is capable of delivering 3.2W into a 4Ω load. The device

outputs can be connected directly to a speaker load for

filterless applications. However, a filter can be added to

ease evaluation. The MAX98357A accepts standard I2S

data and the MAX98357B accepts left-justified digital

audio data. Both versions also support 8-channel TDM

audio data.

The MAX98357 evaluation system (EV system) includes

the MAX98357 DEV board and Maxim Integrated’s audio

interface board (MAXAUDINT001# board).

The MAXAUDINT001# board provides an easy-to-use

USB audio-to-I2S converter. This allows for any computer

to become a digital audio source, which can be used to

evaluate the devices. The MAXAUDINT001# board can

also be used to power the MAX98357. This allows for a

complete evaluation from a single USB connection.

Features

●2.5V to 5.5V Single-Supply Operation

●Only a Single External Component (VDD Capacitor)

Required in Many Applications

●I2S, Left-Justified, or TDM Input

●Five Selectable Gains (3db, 6dB, 9dB, 12dB, and

15dB)

●Audio Channel Select (Left, Right, and Mono Mix)

●Filterless Operation

●Optional Class D Output Filters for Ease of

Evaluation

●Proven PCB Layout

●Fully Assembled and Tested

Figure 1. Simplified Block Diagram

10µF 0.1µF

VDD GAIN_SLOT

2.5V TO 5.5V

DAC

MAX98357

DIGITAL

AUDIO

INTERFACE

CLASS D

OUTPUT STAGE

OUTP

OUTN

AUDIO

INTERFACE

BOARD

LRCLK

PCM

BCLK

DIN

SD_MODE

Click here for production status of specic part numbers.

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

Quick Start

Recommended Equipment

• MAX98357 EV system

• 2.5V to 5.5V, 2A DC power supply

• USB audio source (from computer through an audio

media player such as iTunes® or Windows Media®

player)

• 4Ω or 8Ω speaker

Procedure

The EV system is fully assembled and tested. Follow the

steps below to verify board operation. Caution: Do not

turn on the power supply until all connections are

completed.

1) Verify that headers and switches are configured as

follows:

JU2: Pins 1-3 (selects left channel)

JU4: Pins 1-2 (power routed from the

MAXAUDINT001# board)

JU5: Pins 1-5 (12dB GAIN_SLOT)

U6: Pins 2-3 (power routed from external supply)

SW1: Position 1-2 (part is on)

2) Set the power-supply output to 5V. Disable the power

supply.

3) Connect the power-supply ground terminal to GND

and the power-supply positive terminal to VIN on the

DEV board.

4) With the audio source disabled, connect the USB

audio source to J1 on the DEV board.

5) Connect the MAXAUDINT001# board to J1 on the DEV

board.

6) Connect the speaker across the OUTP and OUTN test

points.

7) Enable the power-supply output.

8) Enable the audio source.

9) Verify that the speakers are playing the audio source

signal.

Detailed Description of Hardware

The MAX98357 EV system is designed to allow a thor-

ough evaluation of the MAX98357 I2S digital input Class D

power amplifier. The DEV board can be used by itself as a

stand-alone evaluation board and driven directly by audio

test equipment. The DEV board can also be used in con-

junction with the MAXAUDINT001# board, which allows for

any computer to become an I2S digital audio source.

The MAXAUDINT001# board has DC regulators that can

be used to power the device. This allows for quick evalu-

ation from a single USB connection. Note that powering

the device from the MAXAUDINT001# board does not

allow for high-power evaluation as the input current is lim-

ited and evaluation with a speaker is not recommended.

Jumpers JU4 and JU6 are used to power the device from

the MAXAUDINT001# board or external supplies con-

nected to test points VIN and VDDIO on the DEV board.

The DEV board operates from a single 2.5V to 5.5V DC

power supply and is capable of delivering 3.2W into a 4Ω

load and 1.75W into an 8Ω load. The device outputs can

be connected directly to a speaker for filterless applica-

tions. However, a filter can be added to ease evaluation.

The LRC components needed for evaluation of a filtered

output are included with the EV kit. The MAX98357A

accepts standard I2S data and the MAX98357B accepts

left-justified digital audio data. Both versions also support

8-channel TDM audio data.

Filterless Output

The DEV board filterless outputs (OUTP, OUTN) can be

connected directly to a speaker load without any filter-

ing. 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 DEV board features optional low-

pass filters at the outputs to ease evaluation. As shipped,

the DEV board’s lowpass filter LRC 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. Use the output posts to connect the filtered

outputs to the audio analyzer. The default lowpass filters at

the DEV board output are optimized for a 4Ω speaker.

iTunes is a registered trademark of Apple Inc.

Windows Media is registered trademark and registered service

mark of Microsoft Corporation.

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

EMI Considerations and Optional Ferrite

Bead Filter

In applications where speaker leads/wires are long

(exceeding approximately 12 inches), additional EMI sup-

pression can be achieved by using a filter constructed from

a ferrite bead (FB1, FB2) and a capacitor to ground (C8,

C9) (Figure 2). Use a ferrite bead with low DC resistance,

high frequency impedance (> 600MHz) between 100Ω

and 600Ω, and rated for at least 1A. The capacitor value

varies based on the ferrite bead chosen and the actual

speaker lead length. Select a capacitor less than 1nF with

the value based upon optimizing EMI performance.

Do not use the optional ferrite bead filter in conjunction

with the optional Class D Filter.

Jumper Selection

Selectable (GAIN_SLOT)

The DEV board features a 5-pin jumper (JU5) to control

the device’s five programmable gain settings. In TDM

mode, the gain is fixed at 12dB and the GAIN_SLOT pin is

repurposed for slot selection. See Table 1 for gain-control

configuration.

SD_MODE Input

The DEV board features a 4-pin jumper (JU2) to control

both the audio channel that is sent to the amplifier output,

along with shutdown mode. JU2 is used to select the

stereo input data between the left channel, right channel,

and the sum of the left/right channels. JU4 must be set to

pins 1-2 and a voltage applied to the +3.3V PCB pad for

proper operation. See Table 2 for shunt positions.

TDM Mode

In TDM mode, the device has a fixed gain of 12dB and the

GAIN_SLOT pin becomes repurposed for slot selection.

The device accepts 8-channel TDM data. The data can

be either 16 bits or 32 bits wide. The GAIN_SLOT pin and

SD_MODE are used to select which of 8 channels of TDM

data the part responds to, as shown in Table 3.

Table 1. JU5 Jumper Selection

(GAIN_SLOT)

Table 2. JU2 Jumper Selection (SD_MODE)

*Default position.

Table 3. TDM Mode Channel Selection

(JU2, JU5)

Figure 2. Optional Ferrite Bead Filter

SHUNT

POSITION

GAIN_SLOT

MAXIMUM

GAIN_SLOT (dB)

1-2 Connected to VDD

through 100kΩ resistor R1 3

1-3 Connected to VDD 6

1-4 Connected to GND

through 100kΩ resistor R2 15

1-5* Connected to GND 12

Not

installed Unconnected 9

SHUNT

POSITION SD_MODE PIN AUDIO

CHANNEL

1-2 Connected to VDDIO

through R3 (small resistor) Right

1-3* Connected to VDDIO

through a 2kΩ resistor Left

1-4 Connected to VDDIO

through R4 (large resistor)

Mono mix

(left + right)/2

JU2 JU5 CHANNEL BITS

Connected low X OFF N/A

1-3 1-5 0 16 or 32

1-3 1-3 1 16 or 32

1-3 OPEN 2 16 or 32

1-3 1-2 3 16 or 32

1-3 1-4 4 16 or 32

1-4 1-5 5 16 or 32

1-4 OPEN 6 16 or 32

1-4 1-3 7 16 or 32

MAX98357A

MAX98357B

OUTP

OUTN

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Evaluates: MAX98357A/MAX98357B

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MAX98357 Development Board/

Evaluation System (WLP)

Shutdown Mode

The device features a low-power shutdown mode that is

activated by setting jumper SW1 to pins 2-3. To exit shut-

down mode, set SW1 to pins 1-2 and select the desired

stereo input channel using jumper JU2. See Table 4 for

shunt positions.

External/Internal VDDIO (+1.8V to +3.3V)

On the DEV board, 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 VDDIO test point or it can be provided from

circuitry on the MAXAUDINT001# board. See Table 5 for

JU4 jumper selection.

Other logic voltages can be used other than +3.3V. If you

want to use other logic voltages, resistors R3 and R4

must be adjusted. Refer to the SD_MODE and Shutdown

Operation section in the MAX98357 IC data sheet for

more information.

VDD Input Supply (+2.5V to +5.5V)

The device can accept an input supply from +2.5V to

+5.5V. This voltage can be applied externally at the

VDD and GND PCB pads, or it can be provided from the

MAXAUDINT001# board. See Table 6 for JU6 jumper

selection.

Audio Interface Board

(MAXAUDINT001# Board)

The MAXAUDINT001# board provides USB-to-I2S data

conversion, as well as DC regulators that can be used

to power the devices. The USB-to-I2S converter on the

MAXAUDINT001# board allows for any computer to

become an I2S digital audio source without requiring

additional driver installation. On the MAXAUDINT001#

board, set SW1 to “demo” and set the I2S switch to con-

nected to source audio by USB. This allows for a quick

evaluation from a single USB connection. Using the

MAXAUDINT001# board as a power supply for high-pow-

er evaluation is not recommended as the input current is

limited. For high-power evaluation, use an external supply

connected to VIN.

Driving I2S Directly

To drive I2S directly, apply signals at the BCLK, LRCLK,

and SDIN test points, or on the J3 header, or between J3

pins 1-2 at the appropriate locations (signal and ground

are labeled on the board).

Evaluating the MAX98357B

The MAX98357 DEV board comes with a MAX98357A

populated on the board, but can also be used to evaluate

the MAX98357B. To evaluate the MAX98357B, carefully

remove the MAX98357A (U1) device from the board and

replace with the MAX98357BEWL+. No other component

changes are required.

Table 5. JU4 Jumper Selection (VDDIO)

Table 6. JU6 Jumper Selection (VDD)

*Default position.

Table 4. SW1 Jumper Selection

*Default position.

SHUNT

POSITION LOGIC VOLTAGE (VDDIO)

1-2* 3.3V supplied by the MAXAUDINT001#

board connected to J1 header.

2-3 User-supplied external power supply applied

at the VDDIO test point.

SHUNT

POSITION INPUT VOLTAGE (VDD)

1-2* VDD supplied from the MAXAUDINT001#

board connected to the J1 header.

2-3 User-supplied external power supply applied

at the VIN PCB pad.

SWITCH

POSITION

VDDIO

VOLTAGE

DEVICE

OPERATION

1-2*

VDDIO determined

by JU4 jumper

position

Normal

(input channel selected

through JU2 setting)

2-3 Connected to GND Shutdown

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Evaluates: MAX98357A/MAX98357B

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MAX98357 Development Board/

Evaluation System (WLP)

Note: Indicate that you are using the MAX98357 when contacting these component suppliers.

DESIGNATION QTY DESCRIPTION

BCLK, DIN,

LRCLK 3Orange multipurpose test

points

C1 1

10µF ±10%, 6.3V X5R

ceramic capacitor (0603)

Murata GRM188R60J106K

C2 1

0.1µF ±10%, 16V X7R

ceramic capacitor (0402)

Murata GRM155R71C104K

C3–C12 0 Not installed, ceramic

capacitors (0402)

FB1, FB2 2 0Ω ±5% resistors (0603)

FOUTN, FOUTP,

GND, VIN 4 Binding posts

FOUTN, FOUTP,

GND (x2), VDD 5

20G plated solid copper bus

wire, 0.25in U-shaped wire

loop

GND (x4), OUTN 5 Black multipurpose test points

(63 mil drill size)

J1 1 26-pin (2 x 13) dual-row right-

angle header, 0.1in centers

J3 1 6-pin header

JU2 1 4-pin header, 0.1 in centers

JU4, JU6 2 3-pin headers, 0.1 in centers

JU5 1 5-pin header, 0.1 in centers

L1, L2 0

Not installed, 22µH inductors

(6.2mm x 6.3mm)—short

(PC trace)

TOKO D63CB series part

TOKO A916CY-220M

OUTP 1 White multipurpose test point

(63 mil drill size)

R1, R2 2 100kΩ ±5% resistors (0603)

R3 1 226kΩ ±1% resistor (0603)

DESIGNATION QTY DESCRIPTION

R4 1 634kΩ ±1% resistor (0603)

R5, R6 0 Not installed, resistors (0402)

R7–R9 3 0Ω ±5% resistors (0603)

U1 1

I2S input Class D audio

amplier (16 WLP)

Maxim MAX98357AEWL+

VDDIO 1 Red multipurpose test point

(63 mil drill size)

SW1 1 SPDT jumper switch, 0.1in

centers

— 4 Shunts

— 1

PCB: MAX98357 WLP

EVKIT DEVELOPMENT

BOARD

OPTIONAL CLASS D FILTER COMPONENTS

C3–C7 7

0.22µF ±10%, 6.3V X5R

ceramic capacitors (0402)

TDK C1005X5R0J224K

L1, L2 2

22µH, 1A inductors

(6.2mm x 6.3mm)

TOKO A916CY-220M

R5, R6 2 22Ω ±5% resistors (0402)

OPTIONAL I2S CONDITIONING COMPONENTS

R7–R9 3 51Ω ±5% resistors (0402)

C10-C12 3 18pF ±5%, 50V, C0G ceramic

capacitors (0402)

OPTIONAL EMI FILTERING COMPONENTS

C8, C9 2

680pF ±10% 50V X54 ceramic

capacitors (0402) TDK

CGA2B1C0G2A681J050BE

FB1, FB2 2 Murata BLM18SG331TN1

(0603)

SUPPLIER PHONE WEBSITE

Murata Americas 770-436-1300 www.murataamericas.com

TDK Corp. 847-803-6100 www.component.tdk.com

TOKO America, Inc. 847-297-0070 www.tokoam.com

Component Suppliers

Component List

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

Figure 3. MAX98357 DEV Board Schematic

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

MAX98357 DEV Board Silkscreen—Top

MAX98357 DEV Board PCB Layout—Layer 2

MAX98357 DEV Board PCB Layout—Component Side

1.0”

MAX98357 EV Kit PCB Layouts

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

#Denotes RoHS compliant.

MAX98357 DEV Board PCB Layout—Solder SideMAX98357 DEV Board PCB Layout—Layer 3

Ordering Information

MAX98357 EV Kit PCB Layouts (continued)

PART TYPE

MAX98357DEV#WLP Development Board

(DEV Board only)

MAX98357EVSYS#WLP

Evaluation System Kit

(DEV + MAXAUDINT001#

Boards)

1.0”

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses

are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time.

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Evaluates: MAX98357A/MAX98357B

(WLP)

MAX98357 Development Board/

Evaluation System (WLP)

Revision History

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 10/13 Initial release —

1 4/14 Added Evaluating the MAX98357B section and updated Figures 2 and 7 4–6, 8

2 9/18 Changed all instances of “AUDINT001” to “MAXAUDINT001#,” added EMI ltering

information and new Figure 2, updated Component List table 1–9

For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.