MAX9820EVKIT データシートの表示（PDF） - Maxim Integrated

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MAX9820EVKIT

MAX9820 Evaluation Kit

Maxim Integrated 

MAX9820 Evaluation Kit

Quick Start

Required Equipment

• 2.7V to 5.5V, 500mA power supply

• One set of stereo headphones

• Audio signal source

Procedure

The MAX9820 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.

1) Verify that a shunt is installed on jumper JU1 (IC

disabled).

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

3) Disable the power-supply output.

4) Connect the power-supply ground to the PGND

PCB pad and the power-supply positive output to

the VDD PCB pad.

5) Verify that the audio source output is disabled.

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

right signal to the GND, VINL, and VINR PCB pads,

respectively.

7) Plug the headphone into the HPOUT headphone jack.

8) Enable the power-supply output.

9) Enable the audio source.

10) Remove the shunt from jumper JU1 (IC enabled).

11) Verify that the headphones are playing the audio

source signal.

Detailed Description of Hardware

The MAX9820 EV kit features the MAX9820 stereo

headphone amplifier, in a 10-pin TDFN package with an

exposed pad, for portable applications. The MAX9820

IC features adjustable gain and DirectDrive outputs.

DirectDrive generates an internal negative supply

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

biasing the output signal at 0V DC. Zero-voltage bias-

ing eliminates the need for bulky DC-blocking capaci-

tors at the output of the amplifier. The MAX9820 oper-

ates from a 2.7V to 5.5V, 500mA power supply.

The EV kit’s gain for each channel is set to -1V/V. The

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

ing the ratio of the corresponding gain-setting resistors

(R1–R4). R1 and R4 set the left-channel gain, while R2

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

channel can be adjusted to a minimum of -1V/V. The IC

delivers up to 95mW into a 32Ω load, while achieving

0.005% THD+N.

Test points OUTR, OUTL, and PGND are provided to

easily measure the output signals.

Shutdown (SHDN)

Jumper JU1 controls the shutdown pin (SHDN) of the

MAX9820, which enables and disables the MAX9820

IC. See Table 1 for jumper JU1 configuration.

Gain Setting

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

gain for both the left and right channels to -1V/V. The

gain can be changed by replacing these resistors with

other surface-mount 0603 resistors. Resistors with a tol-

erance of 1% or better are recommended for optimum

performance. Use Table 2 and the following equations

to select new gain-setting resistors for the correspond-

ing channel.

RIN >

1

2π × 20Hz × CIN

RFB ≥10kΩ

RIN = RFB

−A

where RIN is the respective input resistance, CIN is the

respective input capacitance, RFB is the respective

feedback resistance, A is the desired gain, and -3dB

frequency is set at 20Hz. The gain for either channel

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

MAX9820 IC data sheet for more details.

Table 1. Shutdown Selection (JU1)

SHUNT

POSITION

Installed

Not installed

SHDN PIN

Connected to PGND

Connected to VDD

through resistor R5

MAX9820

FUNCTION

Disabled

Enabled

Table 2. Component Function

CHANNEL

RIN

RFB

CIN

Right

R2

R3

C2

Left

R1

R4

C1

2 _______________________________________________________________________________________

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