MAX9724AEVKIT [MAXIM]

Fully Assembled and Tested;


型号：	MAX9724AEVKIT
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Fully Assembled and Tested
文件：	总4页 (文件大小：115K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

19-3203; Rev 0; 1/08

MAX9724A Evaluation Kit

Evluates:/MAX9724B

General Description

Features

The MAX9724A evaluation kit (EV kit) is a fully assem-

bled and tested printed-circuit board (PCB) that uses

the MAX9724A IC to drive a stereo headphone in

portable applications. The MAX9724A is a 60mW stereo

headphone amplifier with adjustable gain and

DirectDrive™ outputs. Maxim’s DirectDrive technology

eliminates the need for bulky DC-blocking capacitors at

the output of the amplifier.

♦ No DC-Blocking Output Capacitors Required

♦ 2.7V to 5.5V Operation

♦ Adjustable -1.5V/V Gain

♦ 60mW per Channel into a 32Ω Load

♦ 0.02% THD+N

The EV kit is configured for a -1.5V/V gain and is

designed to operate from a 2.7V to 5.5V DC power sup-

ply. The EV kit is capable of delivering up to 60mW per

channel into a 32Ω load and achieving 0.02% THD+N.

♦ Fully Assembled and Tested

The MAX9724A EV kit can also be used to evaluate the

MAX9724B fixed-gain amplifier. Contact Maxim for a

free sample of the MAX9724B IC.

Ordering Information

PART

TYPE

MAX9724AEVKIT+

EV Kit

+Denotes lead-free and RoHS-compliant.

Component List

DESIGNATION QTY

DESCRIPTION

DESIGNATION QTY

DESCRIPTION

1µF 10%, 10V X5R ceramic

capacitors (0603)

Murata GRM188R61A105K

OUTL, OUTR,

Not installed, test points

C1, C2, C4

SGND

R1, R3

R2, R4

10kΩ 1% resistors (0603)

15kΩ 1% resistors (0603)

60mW, DirectDrive, stereo headphone

amplifier (12-pin TQFN-EP*)

Maxim MAX9724AETC+

0.1µF 10%, 10V X5R ceramic

capacitor (0402)

Murata GRM155R61A104K

0.47µF 10%, 10V X5R ceramic

capacitors (0603)

Murata GRM188R61A474K

C5, C6

—

Shunt (JU1)

PCB: MAX9724A Evaluation Kit+

JU1

3-pin header

*EP = Exposed paddle.

OUT

Stereo headphone jack (3.5mm)

Component Supplier

SUPPLIER

Murata Mfg. Co., Ltd.

Note: Indicate that you are using the MAX9724A when contacting this component supplier.

PHONE

WEBSITE

770-436-1300

www.murata.com

________________________________________________________________ Maxim Integrated Products

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.

MAX9724A Evaluation Kit

Test points OUTR, OUTL, and SGND are provided to

easily measure the output signals.

Quick Start

Required Equipment

Before beginning, the following equipment is needed:

The MAX9724A EV kit can evaluate the fixed-gain

MAX9724B IC, also in a 12-pin thin QFN package. The

MAX9724B features a fixed gain of -1.5V/V. See the

Evaluating the MAX9724B section for more information.

• 2.7V to 5.5V, 500mA power supply

• 32Ω stereo headphones with a 3.5mm plug

• Audio signal source

Shutdown (SHDN)

Jumper JU1 controls the shutdown pin (SHDN) of the

MAX9724A that enables and disables the MAX9724A

IC. See Table 1 for jumper JU1 configurations.

Procedure

The MAX9724A 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

connections are completed.

Table 1. Jumper JU1 Shutdown Selection

MAX9724A

FUNCTION

1) Verify that a shunt is installed on jumper JU1, pins

2-3 (IC disabled).

SHUNT POSITION

SHDN PIN

1-2

2-3

Connected to VDD

Connected to GND

Enabled

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

3) Disable the power-supply output.

Disabled

4) Connect the power-supply ground to the PGND pad

and the power-supply positive output to the VDD pad.

Gain Setting

The default gain-setting resistors R1–R4 configure the gain

for both the left and right channels to -1.5V/V. The gain

can be changed by replacing these resistors with other

surface-mount 0603 resistors. Resistors with a tolerance of

1% or better are recommended for optimum performance.

Use Table 2 and the following equation to select new gain-

setting resistors for the corresponding channel.

5) Verify that the audio source output is disabled.

6) Connect the audio source ground, left signal, and right

signal to the SGND, INL, and INR pads, respectively.

7) Plug the headphone into the OUT headphone jack.

8) Enable the power-supply output.

9) Enable the audio source.

Table 2. Gain-Setting Resistors

10) Install a shunt on jumper JU1 across pins 1-2 (IC

enabled).

CHANNEL

Right

RIN

Evluates:/MAX9724B

11) Verify that the headphones are playing the audio

source signal.

Left

Detailed Description

RF = -A • RIN

The MAX9724A EV kit features the MAX9724A IC stereo

headphone amplifier. The MAX9724A features

adjustable gain and 60mW DirectDrive outputs.

DirectDrive generates an internal negative supply

(-VDD) from the positive supply (VDD), thus biasing the

amplifier output. Zero-voltage biasing eliminates the

need for bulky DC-blocking capacitors at the amplifier

output. The MAX9724A operates from a 2.7V to 5.5V

supply with a low quiescent current of 3.5mA. The

MAX9724A comes in a 12-pin thin QFN package suit-

able for portable applications.

where RIN ≥ 10kΩ and A is the desired negative gain.

Refer to the Output Dynamic Range and Maximum

Output Swing sections in the MAX9724A/MAX9724B IC

data sheet for limitations on setting the gain.

Evaluating the MAX9724B

The MAX9724A EV kit can evaluate the fixed-gain

MAX9724B IC after performing the following:

1) Replace U1 with the MAX9724B IC.

The EV kit’s gain for each channel is set to -1.5V/V. The

left- and right-channel gain can be adjusted by modifying

the ratio of the corresponding gain-setting resistors R1–R4.

R1 and R2 set the right-channel gain and R3 and R4 set

the left-channel gain. The IC delivers up to 60mW per

channel into a 32Ω load while achieving 0.02% THD+N.

2) Remove resistors R2 and R4.

3) Replace resistors R1 and R3 with 0Ω 0603 surface-

mount resistors.

The MAX9724B features a fixed-gain of -1.5V/V. Contact

Maxim for a free sample of the MAX9724BETC+.

_______________________________________________________________________________________

MAX9724A Evaluation Kit

Evluates:/MAX9724B

VDD

1μF

0.1μF

PGND

15kΩ

OUTR

OUTL

INR

INL

OUT

INR

OUTR

OUTL

10kΩ

0.47μF

15kΩ

OUTL

MAX9724A

INL

SGND

C1P

C1N

10kΩ

VDD

0.47μF

1μF

JU1

SGND

SHDN

1μF

Figure 1. MAX9724A EV Kit Schematic

_______________________________________________________________________________________

MAX9724A Evaluation Kit

Figure 2. MAX9724A EV Kit Component Placement Guide—

Component Side

Figure 3. MAX9724A EV Kit PCB Layout—Component Side

Evluates:/MAX9724B

Figure 4. MAX9724A EV Kit PCB Layout—Solder Side

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.

4 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

is a registered trademark of Maxim Integrated Products, Inc.

MAX9724AEVKIT [MAXIM]

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