MAX9759ETE(2005_10) View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX9759ETE
(Rev.:2005_10)

3.2W, High-Efficiency, Low-EMI, Filterless, Class D Audio Amplifier

Maxim Integrated 

3.2W, High-Efficiency, Low-EMI,

Filterless, Class D Audio Amplifier

PIN

1

2

3

4

5

6, 14

7

8

9, 12

10

11

13

15

16

EP

Pin Description

NAME

VDD

IN+

IN-

GND

SHDN

PGND

SYNC

MUTE

PVDD

OUT-

OUT+

SYNC_OUT

G2

G1

EP

FUNCTION

Analog Power Supply. Bypass to GND with a 1µF ceramic capacitor.

Noninverting Audio Input

Inverting Audio Input

Analog Ground

Active-Low Shutdown Input. Drive SHDN low to shut down the MAX9759. Connect to VDD for normal

operation.

Power Ground

Frequency Select and External Clock Input:

SYNC = GND: Fixed-frequency mode with fS = 1100kHz.

SYNC = FLOAT: Fixed-frequency mode with fS = 1500kHz.

SYNC = VDD: Spread-spectrum mode with fS = 1200kHz ±70kHz.

SYNC = Clocked: Fixed-frequency mode with fS = external clock frequency.

Active-Low Mute Function. Drive MUTE low to disable the H-bridge outputs. Connect to VDD for

normal operation.

H-Bridge Power Supply. Bypass to PGND with a 10µF ceramic capacitor.

Negative Speaker Output

Positive Speaker Output

Internal Clock Output. Connect SYNC_OUT to the clock input of cascaded Maxim Class D

amplifiers. Float SYNC_OUT if unused.

Gain Control 2 (See Table 2)

Gain Control 1 (See Table 2)

Exposed Paddle. Can be left floating or tied to GND. For optimum thermal performance, connect EP

to GND.

Detailed Description

Operating Modes

The MAX9759 filterless, Class D audio power amplifier

features several improvements to switch-mode amplifier

technology. The MAX9759 offers Class AB performance

with Class D efficiency, while occupying minimal board

space. A unique modulation scheme, synchronizable

switching frequency, and SSM mode create a compact,

flexible, low-noise, efficient audio power amplifier. The

differential input architecture reduces common-mode

noise pickup, and can be used without input-coupling

capacitors. The device can also be configured as a sin-

gle-ended input amplifier.

Comparators monitor the MAX9759 inputs and com-

pare the complementary input voltages to the sawtooth

waveform. The comparators trip when the input magni-

tude of the sawtooth exceeds their corresponding input

voltage. Both comparators reset at a fixed time after the

rising edge of the second comparator trip point, gener-

ating a minimum-width pulse tON(MIN) at the output of

the second comparator (Figure 1). As the input voltage

increases or decreases, the duration of the pulse at

one output increases (the first comparator to trip) while

the other output pulse duration remains at tON(MIN).

This causes the net voltage across the speaker (VOUT+

- VOUT-) to change.

Fixed-Frequency Modulation (FFM) Mode

The MAX9759 features two FFM modes. The FFM

modes are selected by setting SYNC = GND for a

1.1MHz switching frequency, and SYNC = FLOAT for a

1.5MHz switching frequency. In FFM mode, the fre-

quency spectrum of the Class D output consists of the

fundamental switching frequency and its associated

harmonics (see the Wideband Output Spectrum (FFM

Mode) graph in the Typical Operating Characteristics).

The MAX9759 allows the switching frequency to be

changed, should the frequency of one or more of the

harmonics fall in a sensitive band. This can be done at

any time and does not affect audio reproduction.

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