MAXIM MAX9759 User Manual

General Description

The MAX9759 mono Class D, audio power amplifier
provides Class AB amplifier audio performance with the
benefits of Class D efficiency, eliminating the need for a
heatsink and extending battery life. The MAX9759 deliv­ers up to 3.2W of continuous power into a 4Ω load while
offering greater than 90% efficiency. Maxim’s next-gen­eration, low-EMI modulation scheme allows the amplifi­er to operate without an external LC filter while still
meeting FCC EMI-radiated emission levels.

The MAX9759 offers two modulation schemes: a fixed­frequency modulation (FFM) mode and a spread-spec­trum modulation (SSM) mode. The SSM mode flattens
the wideband spectral components, reducing EMI-radi­ated emissions due to the modulation frequency.
Furthermore, the MAX9759 oscillator can be synchro­nized to an external clock through the SYNC input,
allowing the switching frequency to range from
1000kHz to 1600kHz. The SYNC input and SYNC_OUT
output of the MAX9759 allow multiple Maxim Class D
amplifiers to be cascaded and frequency locked, mini­mizing interference due to clock intermodulation. The
MAX9759 utilizes fully differential input amplifiers, a full­bridged output, comprehensive click-and-pop suppres­sion, and features four selectable gain settings (6dB,
12dB, 18dB, 24dB).

The MAX9759 features high 81dB PSRR, low 0.02%
THD+N, and SNR in excess of 90dB. Short-circuit and
thermal-overload protection prevents damage to the
device during a fault condition. The MAX9759 operates
from a single 5V supply, consumes 8.4mA of supply
current, and is available in a 16-pin thin QFN package
(4mm x 4mm x 0.8mm). The MAX9759 is fully specified
over the extended -40°C to +85°C temperature range.

Applications

Cell Phones/PDAs

Notebook PCs

Portable DVD Players

Flat-Panel PC Monitors

LCD TVs

LCD Projectors

Features

♦ 3.2W into 4Ω Load (THD+N = 10%)

♦ Filterless Amplifier Passes FCC Radiated

Emissions Standards with 7.6cm of Cable

♦ 92% Efficiency

♦ High PSRR (81dB at 1kHz)

♦ Low 0.02% THD+N

♦ External Clock Synchronization for Multiple,

Cascaded Maxim Class D Amplifiers

♦ 3.0V to 5.5V Single-Supply Operation

♦ Pin-Selectable Gain (6dB, 12dB, 18dB, 24dB)

♦ Integrated Click-and-Pop Suppression

♦ Low Quiescent Current (8.4mA)

♦ Low-Power Shutdown Mode (10µA)

♦ Mute Function

♦ Short-Circuit and Thermal-Overload Protection

♦ Available in Thermally Efficient Package

16-Pin TQFN (4mm x 4mm x 0.8mm)

MAX9759

3.2W, High-Efficiency, Low-EMI,

Filterless, Class D Audio Amplifier

________________________________________________________________ Maxim Integrated Products 1

MAX9759

DIFFERENTIAL

AUDIO INPUT

SYNC

INPUT

SYNC

OUTPUT

V

DD

OSCILLATOR

MODULATOR

AND H-BRIDGE

MONO SPEAKER
OUTPUT

GAIN

CONTROL

MUTE

CONTROL

SHDN

CONTROL

G1
G2

SHDN

MUTE

Simplified Block Diagram

Ordering Information

19-3691; Rev 1; 10/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

PART

TEMP RANGE

PIN-

PKG

CODE

MAX9759ETE+

T1644-4

Pin Configurations appear at end of data sheet.

+Denotes lead-free package.

*EP = Exposed paddle.

PACKAGE

-40°C to +85°C 16 TQFN-EP*

MAX9759

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

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VDDto GND..............................................................................6V

PV

DD

to PGND .........................................................................6V

GND to PGND .......................................................-0.3V to +0.3V

All Other Pins to GND.................................-0.3V to (V

DD

+ 0.3V)

Continuous Current Into/Out of PV

DD

/PGND/OUT+/OUT-....1.7A

Duration of OUT+ or OUT- Short Circuit to

V

DD

/GND/PVDD/PGND............................................Continuous

Duration of Short Circuit Between OUT+ and OUT- ..Continuous

Continuous Power Dissipation (T

A

= +70°C)

16-Pin TQFN (derate 16.9mW/°C above +70°C) .....1349.1mW

Junction Temperature......................................................+150°C

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ESD Protection (+IBM).........................................................±2kV

ELECTRICAL CHARACTERISTICS (VDD= 5.0V)

(VDD= PVDD= SHDN = MUTE = 5V, GND = PGND = 0V, SYNC = 0V (FFM). Gain = 12dB (G1 = 0, G2 = 1). Speaker load resistor

(R

L

) connected between OUT+ and OUT-, unless otherwise noted, RL= ∞, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical val-

ues are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

GENERAL

Supply Voltage Range V

DD

Inferred from PSRR test 3.0 5.5 V

Quiescent Current I

DD

No load 8.4 12 mA

Mute Current I

MUTE

V

MUTE

= 0V 5.5 8 mA

Shutdown Current

(

)

V

SHDN

= 0V 0.1 10 µA

Shutdown to Full Operation t

SON

40 ms

Mute to Full Operation t

MUTE

40 ms

Common-Mode Rejection Ratio CMRR f = 1kHz, input referred, VIN = 200mV

P-P

67 dB

Input DC Bias Voltage V

CM

1.3 1.5 1.7 V

Gain = +24dB 14 20 26

Gain = +18dB 25 36 47

Gain = +12dB 40 60 80

Input Resistance R

IN

Gain = +6dB 60 90 120

kΩ

G1 = 0, G2 = 0

G1 = 1, G2 = 0

G1 = 0, G2 = 1

Voltage Gain A

V

G1 = 1, G2 = 1 +4 +6 +8

dB

Output Offset Voltage V

OS

TA = +25°C

±50 mV

VDD = 4.5V to 5.5V 62 90

f

RIPPLE

= 217Hz 79

f

RIPPLE

= 1kHz 81

Power-Supply Rejection Ratio
(Note 3)

PSRR

200mV

P-P

ripple

f

RIPPLE

= 20kHz 70

dB

I

SHDN

DD

+22 +24 +26

+16 +18 +20

+10 +12 +14

±10

MAX9759

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

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (VDD= 5.0V) (continued)

(VDD= PVDD= SHDN = MUTE = 5V, GND = PGND = 0V, SYNC = 0V (FFM). Gain = 12dB (G1 = 0, G2 = 1). Speaker load resistor
(R

L

) connected between OUT+ and OUT-, unless otherwise noted, RL= ∞, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical val-

ues are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER

CONDITIONS

UNITS

RL = 3Ω 3.4

RL = 4Ω 2.6THD+N = 1%

R

L

= 8Ω 1.4

RL = 3Ω 4.3

RL = 4Ω 3.2

Output Power P

OUT

THD+N = 10%

R

L

= 8Ω 1.8

W

RL = 3Ω

RL = 4Ω

Total Harmonic Distortion Plus
Noise

fIN = 1kHz, either
FFM or SSM,
P

OUT

= 1W

R

L

= 8Ω

%

FFM 93

BW = 22Hz to
22kHz

SSM 89

FFM 96

Signal-to-Noise Ratio SNR

P

OUT

= 1W,

R

L

= 8Ω

A-weighted

SSM 92

dB

SYNC = GND (FFM mode)

SYNC = FLOAT (FFM mode)

Oscillator Frequency f

OSC

SYNC = VDD (SSM mode)

1200

kHz

SYNC Frequency Lock Range TTL-compatible clock input

kHz

Into shutdown -50

Click-and-Pop Level K

CP

Peak voltage,
A-weighted, 32 samples

-57

dBV

Efficiency η

P

OUT

= 1W, fIN = 1kHz, RL = 8Ω in series

with 68µH

92 %

DIGITAL INPUTS (SHDN, MUTE, G1, G2, SYNC)

SYNC, G1, G2 Input Voltage High

V

INH

VDD x 0.9 V

SYNC, G1, G2 Input Voltage Low

V

INL

V

SHDN, MUTE Voltage High V

INH

2V

SHDN, MUTE Voltage Low V

INL

0.8 V

SYNC Input Resistance

kΩ

SYNC Input Current ±35 µA
SHDN, MUTE, G1, G2 Input

Current

±1µA

SYNC Capacitance 10 pF

DIGITAL OUTPUTS (SYNC_OUT)

Output Voltage High V

OH

IOH = 3mA 2.4 V

Output Voltage Low V

OL

IOL = 3mA 0.4 V

SYNC_OUT Capacitive Drive TTL-compatible clock output

pF

SYMBOL

THD+N

per second (Notes 3, 4)

Out of shutdown

MIN TYP MAX

0.08

0.05

0.02

1000 1100 1200

1102 1500 1837

±70

1000 1600

200

100

VDD x 0.1

MAX9759

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

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (VDD= 3.3V)

(VDD= PVDD= SHDN = MUTE = 3.3V, GND = PGND = 0V, SYNC = GND (FFM). Gain = 12dB (G1 = 0, G2 = 1). Speaker load resis­tor (R

L

) connected between OUT+ and OUT-, unless otherwise noted. RL= ∞, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical

values are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER

CONDITIONS

UNITS

Quiescent Current I

DD

6mA

Mute Current I

MUTE

V

MUTE

= 0V 5 A

Shutdown Current I

SHDN

V

SHDN

= 0V 0.1 µA

Common-Mode Rejection Ratio CMRR f = 1kHz, input referred 67 dB

VDD = 3.0V to 5.5V 50 72 dB

f

RIPPLE

= 217Hz 79

f

RIPPLE

= 1kHz 81

Power-Supply Rejection Ratio PSRR

200mV

P-P

ripple

f

RIPPLE

= 20kHz 70

dB

RL = 3Ω 1.5

RL = 4Ω 1.1

THD+N = 1%

R

L

= 8Ω

RL = 3Ω 1.8

RL = 4Ω 1.3

Output Power P

OUT

THD+N = 10%

R

L

= 8Ω

W

RL = 3Ω

RL = 4Ω

Total Harmonic Distortion Plus
Noise

f = 1kHz, either
FFM or SSM,
P

OUT

= 500mW

R

L

= 8Ω

%

FFM 93

BW = 22Hz
to 22kHz

SSM 89

FFM 96

Signal-to-Noise Ratio SNR

P

OUT

= 500mW,

R

L

= 8Ω

SSM 92

dB

Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R

L

= 4Ω, L = 33µH.

For R

L

= 8Ω, L = 68µH.

Note 3: Inputs AC-coupled to GND.
Note 4: Testing performed with 8Ω resistive load in series with a 68µH inductive load across BTL outputs. Mode transitions are con-

trolled by the SHDN pin.

SYMBOL

MIN TYP MAX

0.65

0.78

0.06

THD+N

0.04

0.02

A-weighted

MAX9759

3.2W, High-Efficiency, Low-EMI,

Filterless, Class D Audio Amplifier

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(VDD= PVDD= SHDN = MUTE = 5V, GND = PGND = 0V, SYNC = VDD(SSM), unless otherwise noted. Gain = 12dB (G1 = 0, G2 = 1).
THD+N measurement bandwidth: 22Hz to 22kHz. Typical values are at T

A

= +25°C.) (See Typical Operating Circuit)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc01

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 5V
R

L

= 3Ω

P

OUT

= 1W

P

OUT

= 2.6W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc02

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 3.3V
R

L

= 3

Ω

P

OUT

= 500mW

P

OUT

= 1.3W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc03

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 5V
R

L

= 4

Ω

P

OUT

= 1W

P

OUT

= 2.2W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc04

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 3.3V
R

L

= 4

Ω

P

OUT

= 500mW

P

OUT

= 700mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc05

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 5V
R

L

= 8

Ω

P

OUT

= 600mW

P

OUT

= 1.2W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc06

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.001

0.1

1

10

10 100k

VDD = 3.3V
R

L

= 8

Ω

P

OUT

= 300mW

P

OUT

= 500mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

MAX9759 toc07

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

10

0.001
10 100k

VDD = 5V
R

L

= 8

Ω

P

OUT

= 1.2W

SSM

FFM

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc08

OUTPUT POWER (W)

THD+N (%)

4321

0.01

0.1

1

10

100

0.001
0

VDD = 5V
R

L

= 3

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc09

OUTPUT POWER (W)

THD+N (%)

1.51.00.5

0.01

0.1

1

10

100

0.001

02.0

VDD = 3.3V
R

L

= 3

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz

MAX9759

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

6 _______________________________________________________________________________________

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc12

OUTPUT POWER (W)

THD+N (%)

1.51.00.5

0.01

0.1

1

10

100

0.001

02.0

VDD = 5V
R

L

= 8

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc13

OUTPUT POWER (W)

THD+N (%)

0.60.40.2

0.01

0.1

1

10

100

0.001
0 0.8

VDD = 3.3V
R

L

= 8

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc14

OUTPUT POWER (W)

THD+N (%)

1.51.00.5

0.01

0.1

1

10

100

0.001

02.0

VDD = 5V
f

IN

= 1kHz

R

L

= 8

Ω

f = 1180kHz, FFM

f = 1400kHz, FFM

EFFICIENCY vs. OUTPUT POWER

MAX9759 toc15

OUTPUT POWER (W)

EFFICIENCY (%)

4321

10

20

30

40

50

60

70

80

90

100

0

05

RL = 8

Ω

RL = 4

Ω

RL = 3

Ω

VDD = 5V
f

IN

= 1kHz

EFFICIENCY vs. OUTPUT POWER

MAX9759 toc16

OUTPUT POWER (W)

EFFICIENCY (%)

1.51.00.5

10

20

30

40

50

60

70

80

90

100

0

02.0

RL = 8

Ω

RL = 4

Ω

RL = 3

Ω

VDD = 3.3V
f

IN

= 1kHz

EFFICIENCY vs. SUPPLY VOLTAGE

MAX9759 toc17

SUPPLY VOLTAGE (V)

EFFICIENCY (%)

5.55.0

4.5

4.03.5

40

50

60

70

80

90

100

30

3.0

RL = 8

Ω

RL = 4

Ω

fIN = 1kHz
THD+N = 1%

OUTPUT POWER

vs. SUPPLY VOLTAGE

MAX9759 toc18

SUPPLY VOLTAGE (V)

OUTPUT POWER (W)

5.5

5.04.54.0

3.5

1

2

3

4

5

6

0

3.0

RL = 3

Ω

f

IN

= 1kHz

THD+N = 1%

THD+N = 10%

Typical Operating Characteristics (continued)

(VDD= PVDD= SHDN = MUTE = 5V, GND = PGND = 0V, SYNC = VDD(SSM), unless otherwise noted. Gain = 12dB (G1 = 0, G2 = 1).
THD+N measurement bandwidth: 22Hz to 22kHz. Typical values are at T

A

= +25°C.) (See Typical Operating Circuit)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc10

OUTPUT POWER (W)

THD+N (%)

3

2

1

0.01

0.1

1

10

100

0.001
0

VDD = 5V
R

L

= 4

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9759 toc11

OUTPUT POWER (W)

THD+N (%)

1.00.5

0.01

0.1

1

10

100

0.001
0 1.5

VDD = 3.3V
R

L

= 4

Ω

fIN = 200Hz, 1kHz

fIN = 10kHz