Input Filter

The fully differential amplifier inputs can be biased at

voltages other than midsupply. The common-mode

feedback circuit adjusts for input bias, ensuring the

outputs are still biased at midsupply. Input capacitors

are not required as long as the common-mode input

voltage is within the specified range listed in the

Electrical Characteristics table.

removes the DC bias from an incoming signal. The AC-

coupling capacitor allows the amplifier to bias the sig-

nal to an optimum DC level. Assuming zero-source

impedance, the -3dB point of the highpass filter is

given by:

response of the amplifier. Use capacitors with

dielectrics that have low-voltage coefficients, such as

tantalum or aluminum electrolytic. Capacitors with high-

voltage coefficients, such as ceramics, can increase

distortion at low frequencies.

BIAS Capacitor

improves PSRR and THD+N by reducing power supply

and other noise sources at the common-mode bias

node, and also generates the clickless/popless startup

DC bias waveform for the speaker amplifiers. Bypass

BIAS with a 0.1µF capacitor to GND. Larger values of

and turn-off times by 10 and improves PSRR by 20dB

(at 1kHz). Do not connect external loads to BIAS.

Supply Bypassing

Proper power-supply bypassing ensures low-noise,

low-distortion performance. Connect a 1µF ceramic

capacitance as required by the application. Locate the

bypass capacitor as close to the device as possible.

Layout and Grounding

Good PC board layout is essential for optimizing perfor-

mance. Use large traces for the power-supply inputs and

amplifier outputs to minimize losses due to parasitic trace

resistance and route heat away from the device. Good

grounding improves audio performance, minimizes

crosstalk between channels, and prevents any digital

switching noise from coupling into the audio signal.

The MAX9718/MAX9719 TDFN, TQFN, TSSOP, and

µMAX packages feature exposed thermal pads on their

undersides. This pad lowers the thermal resistance of the

package by providing a direct-heat conduction path

from the die to the PC board. Connect the exposed pad

to the ground plane using multiple vias, if required.

UCSP Applications Information

For the latest application details on UCSP construction,

dimensions, tape carrier information, PC board tech-

niques, bump-pad layout, and recommended reflow

temperature profile, as well as the latest information on

reliability testing results, refer to the Application Note:

UCSP—A Wafer-Level Chip-Scale Package available

on Maxim’s website at www.maxim-ic.com/ucsp.

f

RC

dB

IN IN

−

=

3

1

2

π

Low-Cost, Mono/Stereo,

1.4W Differential Audio Power Amplifiers

12

______________________________________________________________________________________

PART

MONO

STEREO

GAIN

(dB)

SELECTABLE

SHUTDOWN

POLARITY

MAX9718A

√

—

Adjustable

√

MAX9718B

√

—

0

√

MAX9718C

√

—

3

√

MAX9718D

√

—

6

√

MAX9719A

—

√

Adjustable

—

MAX9719B

—

√

0

—

MAX9719C

—

√

3

—

MAX9719D

—

√

6

—

Selector Guide