MAX9725E [MAXIM]

Fully Assembled and Tested;


型号：	MAX9725E
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Fully Assembled and Tested
文件：	总5页 (文件大小：116K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

19-4038; Rev 0; 2/08

MAX9725E Evaluation Kit

vluates:–MAX9725E

General Description

Features

♦ No DC-Blocking Output Capacitors Required

♦ 0.9V to 1.8V Operation

The MAX9725E evaluation kit (EV kit) is a fully assem-

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

the MAX9725E IC to drive a stereo headphone in

portable applications. The MAX9725E is a low-power

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.

♦ Adjustable -1.82V/V Gain

♦ 20mW per Channel into a 32ΩΩ Load

♦ Low 0.006% THD+N

The EV kit is configured for a -1.82V/V gain and is

designed to operate from a 0.9V to 1.8V DC power sup-

ply. The EV kit is capable of delivering up to 20mW per

channel into a 32Ω load and achieves 0.006% THD+N.

♦ Fully Assembled and Tested

The MAX9725E EV kit can also be used to evaluate the

MAX9725A, MAX9725B, MAX9725C, or MAX9725D

fixed-gain amplifiers. Contact Maxim for free samples of

the MAX9725A, MAX9725B, MAX9725C, or MAX9725D.

See the Part Selection Table for IC ordering information.

The MAX9725_ IC temperature range is -40°C to +85°C.

Part Selection Table

Ordering Information

PART

TYPE

PART

GAIN

MAX9725EEVKIT+

EV Kit

MAX9725AEBC+

MAX9725BEBC+

MAX9725CEBC+

MAX9725DEBC+

MAX9725EEBC+

-2

-1.5

+Denotes lead-free and RoHS-compliant.

-1

-4

Adjustable

Component List

DESIGNATION QTY

DESCRIPTION

DESIGNATION QTY

DESCRIPTION

1µF 10%, 10V X5R ceramic

capacitors (0603)

Murata GRM188R61A105K

OUTL, OUTR,

C1, C2, C3, C5,

Not installed, test points

SGND

R1, R2, R5

R3, R4

10kΩ 1% resistors (0603)

18.2kΩ 1% resistors (0603)

4.7µF 10%, 6.3V X5R ceramic

capacitor (0603)

Murata GRM188R60J475K

Fixed-gain, stereo headphone

amplifier (12-bump UCSP™,

1.54mm x 2.02mm x 0.6mm)

Maxim MAX9725EEBC+

120Ω at 100MHz, 25mΩ DCR, 3A

ferrite beads (0603)

Murata BLM18SG121TN1

FB1, FB2, FB3

—

Shunt (JU1)

JU1

2-pin header

PCB: MAX9725E Evaluation Kit+

OUT

Stereo headphone jack (3.5mm)

Component Supplier

SUPPLIER

Murata Mfg. Co., Ltd.

PHONE

WEBSITE

770-436-1300

www.murata.com

Note: Indicate that you are using the MAX9725E when contacting this component supplier.

UCSP is a trademark of Maxim Integrated Products, Inc.

________________________________________________________________ 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.

MAX9725E Evaluation Kit

either channel can be adjusted to a minimum of |-1V/V|.

The IC delivers up to 20mW per channel into a 32Ω

load while achieving 0.006% THD+N.

Quick Start

Required Equipment

Before beginning, the following equipment is needed:

Test points OUTL, OUTR, and SGND are provided to

easily measure the output signals.

•

0.9V to 1.8V, 500mA power supply

32Ω stereo headphones with a 3.5mm plug

Audio signal source (e.g., MP3 player, CD player, etc.)

The MAX9725E EV kit can also evaluate the fixed-gain

MAX9725A, MAX9725B, MAX9725C, or MAX9725D

ICs. See the Evaluating the MAX9725A–MAX9725D

section for more information.

Procedure

The MAX9725E 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.

Shutdown (SHDN)

Jumper JU1 controls the shutdown pin (SHDN) of the

MAX9725E that enables and disables the MAX9725E

IC. See Table 1 for jumper JU1 configurations.

1) Verify that a shunt is not installed on jumper JU1 (IC

disabled).

Table 1. Jumper JU1 Shutdown Selection

2) Set the power-supply output to 1.8V.

3) Disable the power-supply output.

MAX9725E

FUNCTION

SHUNT POSITION

Installed

SHDN PIN

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

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

Connected to VDD

Enabled

Connected to GND

through R5

Not installed

Disabled

5) Verify that the audio source output is disabled.

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

right signal to the SGND, VINL, and VINR pads,

respectively.

Gain Setting

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

gain for both left and right channels to -1.82V/V. The gain

can be changed by replacing resistors R1–R4 with other

surface-mount 0603 resistors. Resistors with a tolerance

of 1% or better are recommended for optimum perfor-

mance. Use Table 2 and the equations that follow to

select new gain-setting resistors for the corresponding

channel.

7) Plug the headphone into the OUT headphone jack.

8) Enable the power-supply output.

9) Enable the audio source.

10) Install a shunt on jumper JU1 (IC enabled).

11) Verify that the headphones are playing the stereo

audio source signal.

vluates:–MAX9725E

Table 2. Component Function

Detailed Description of Hardware

The MAX9725E EV kit features the MAX9725E IC stereo

headphone amplifier in a tiny (1.54mm x 2.02mm x

0.6mm) 12-bump UCSP package for portable applica-

tions. The MAX9725E IC features adjustable gain and

low-power DirectDrive outputs. DirectDrive generates

an internal negative supply (-VDD) from the positive

supply (VDD), thus biasing the output signal at 0V DC.

Zero-voltage biasing eliminates the need for bulky DC-

blocking capacitors at the output of the amplifier. The

MAX9725E operates from a 0.9V to 1.8V supply with a

low quiescent current of 2.3mA.

CHANNEL

Right

RIN

RFB

CIN

Left

RIN >

2π ×20Hz×CIN

RFB ≥ 10kΩ

RFB

RIN =

The EV kit’s gain for each channel is set to -1.82V/V.

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

modifying the ratio of the corresponding gain-setting

resistors, R1–R4. R1 and R4 set the left-channel gain;

R2 and R3 set the right-channel gain. The gain for

−A

where A is the desired gain. The gain for either channel

can be adjusted to a minimum of |-1V/V|. Refer to the

MAX9725 IC data sheet for more details.

_______________________________________________________________________________________

MAX9725E Evaluation Kit

vluates:–MAX9725E

Evaluating the MAX9725A–MAX9725D

The MAX9725E EV kit can also evaluate the fixed-gain

MAX9725A, MAX9725B, MAX9725C, or MAX9725D ICs

after performing the following:

1) Replace U1 with the alternate MAX9725 IC.

2) Replace resistors R1 and R2 with 0Ω 0603 surface-

mount resistors.

3) Remove resistors R3 and R4.

VDD

FB3

FERRITE

VDD

4.7µF

1µF

PGND

18.2kΩ

10kΩ

1µF

OUTR

OUTL

OUTR

PGND

OUTR

OUTL

FB1

FERRITE

OUT

VINL

INL

OUTR

18.2kΩ

OUTL

SGND

10kΩ

FB2

FERRITE

1µF

MAX9725E

OUTL

VINR

INR

VDD

SGND

1µF

C1N

C1P

JU1

1µF

SHDN

10kΩ

SGND

Figure 1. MAX9725E EV Kit Schematic

_______________________________________________________________________________________

MAX9725E Evaluation Kit

Figure 2. MAX9725E EV Kit Component Placement Guide—

Component Side

Figure 3. MAX9725E EV Kit PCB Layout—Component Side

vluates:–MAX9725E

_______________________________________________________________________________________

MAX9725E Evaluation Kit

vluates:–MAX9725E

Figure 4. MAX9725E 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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5

is a registered trademark of Maxim Integrated Products, Inc.

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