Detailed Description

The MAX9716/MAX9717 are 1.3W BTL speaker ampli-

fiers. Both devices feature a low-power shutdown

mode, and industry-leading click-and-pop suppression.

The MAX9717 features a headphone sense input that

disables the slave BTL amplifier to drive the headphone

as a single-ended load. These devices consist of high

output-current audio amps configured as BTL ampli-

fiers (see Functional Diagrams). The closed-loop gain

of the input op amp sets the single-ended gain of the

device. Two external gain resistors set the gain of the

MAX9716 and MAX9717A (see the Gain-Setting

Resistor section). The MAX9717B/C/D feature internally

set gains of 6dB, 9dB, and 12dB, respectively.

The output of the first amplifier serves as the input of the

second amplifier, which is configured as an inverting

unity-gain follower. This results in two outputs, identical in

amplitude, but 180° out-of-phase.

BIAS

The MAX9716/MAX9717 operate from a single 2.7V to

5.5V supply and feature an internally generated, common-

provides both click-and-pop suppression and sets the DC

bias level for the audio outputs. The MAX9716 can be

configured as a single-ended or differential input. For sin-

gle-ended input, connect the noninverting input IN+ to

BIAS externally. The MAX9717 BIAS is internally connect-

ed to the amplifier noninverting input IN+.

The MAX9717 can only be used with a single-ended

input. Always bypass BIAS to ground with a capacitor.

Choose the value of the bypass capacitor as described in

the BIAS Capacitor section. Do not connect external loads

to BIAS. Any load lowers the BIAS voltage, affecting the

overall performance of the device.

BTL/SE Control Input

The MAX9717 features a headphone sense input,

BTL/SE, that enables headphone jack sensing to con-

trol the power amplifier output configuration. Driving

BTL/SE low enables the slave amplifier (OUT-). Driving

BTL/SE high disables the slave amplifier.

Shutdown Mode

The MAX9716/MAX9717 feature a low-power shutdown

mode that reduces quiescent current consumption to

10nA. Entering shutdown disables the bias circuitry,

forces the amplifier outputs to GND through an internal

20k

Ω resistor. Drive SHDN low to enter shutdown

mode; drive SHDN high for normal operation.

Click-and-Pop Suppression

The MAX9716/MAX9717 feature Maxim’s industry-leading

click-and-pop suppression circuitry. During startup, the

amplifier common-mode bias voltage ramps to the DC

bias. When entering shutdown, the amplifier outputs are

pulled to GND through an internal 20k

Ω resistor. This

scheme minimizes the energy present in the audio band.

Low-Cost, Mono, 1.4W BTL Audio Power

Amplifiers

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9

Pin Description

PIN

BUMP

TDFN/µMAX

UCSP

MAX9716

MAX9717

MAX9716

MAX9717

NAME

FUNCTION

1

1

C3

C3

SHDN

Active-Low Shutdown

2

2

C1

C1

BIAS

DC Bias Bypass Capacitor Connection. Bypass BIAS to ground with a

1µF capacitor.

3

—

A3

—

IN+

Noninverting Input

4

4

A1

A1

IN-

Inverting Input

5

5

A2

A2

OUT+

Bridge Amplifier Positive Output

6

6

B3

B3

77

B1, B2

B1, B2

GND

Ground

8

8

C2

C2

OUT-

Bridge Amplifier Negative Output. OUT- becomes high-impedance

when BTL/SE is driven high.

—3

—

A3

BTL/SE

BTL/Single-Ended Mode Input. Logic low sets the device in BTL mode.

Logic high sets the device in single-ended mode.

EP

EP

—

—

EP

Exposed Pad. Connect EP to GND.