MAXIM MAX9709 Technical data

General Description

The MAX9709 stereo/mono, Class D audio power amplifi­er delivers up to 2 x 25W into an 8Ω stereo mode and
1 x 50W into a 4Ω load in mono mode while offering up to
87% efficiency. The MAX9709 provides Class AB amplifi­er performance with the benefits of Class D efficiency,
eliminating the need for a bulky heatsink and conserving
power. The MAX9709 operates from a single +10V to
+22V supply, driving the load in a BTL configuration.

The MAX9709 offers two modulation schemes: a fixed-fre­quency modulation (FFM) mode, and a spread-spectrum
modulation (SSM) mode that reduces EMI-radiated emis­sions. The MAX9709 can be synchronized to an external
clock from 600kHz to 1.2MHz. A synchronized output
allows multiple units to be cascaded in the system.

Features include fully differential inputs, comprehensive
click-and-pop suppression, and four selectable-gain set­tings (22dB, 25dB, 29.5dB, and 36dB). A pin-program­mable thermal flag provides seven different thermal
warning thresholds. Short-circuit and thermal-overload
protection prevent the device from being damaged
during a fault condition.

The MAX9709 is available in 56-pin TQFN (8mm x 8mm
x 0.8mm) and 64-pin TQFP (10mm x 10mm x 1.4mm)
packages, and is specified over the extended

-40°C to +85°C temperature range.

Applications

LCD TVs PDP TVs

Automotive PC/HiFi Audio Solutions

Features

♦ 2 x 25W Output Power in Stereo Mode

(8Ω, THD = 10%)

♦ 1 x 50W Output Power in Mono Mode

(4Ω, THD = 10%)

♦ High Efficiency: Up to 87%
♦ Filterless Class D Amplifier
♦ Unique Patented Spread-Spectrum Mode
♦ Programmable Gain (+22dB, +25dB, +29.5dB,

+36dB)

♦ High PSRR (90dB at 1kHz)
♦ Differential Inputs Suppress Common-Mode

Noise

♦ Shutdown and Mute Control
♦ Integrated Click-and-Pop Suppression
♦ Low 0.1% THD+N
♦ Current Limit and Thermal Protection
♦ Programmable Thermal Flag
♦ Clock Synchronization Input and Output
♦ Available in Thermally Efficient, Space-Saving

Packages: 56-Pin TQFN and 64-Pin TQFP

MAX9709

25W/50W, Filterless, Spread-Spectrum,

Stereo/Mono, Class D Amplifier

________________________________________________________________ Maxim Integrated Products 1

Simplified Block Diagram

Ordering Information

19-3769; Rev 0; 9/05

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.

+Denotes lead-free package.
*Future product—Contact factory for availability.
**EP = Exposed paddle.

Pin Configurations appear at end of data sheet.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX9709ETN+ -40°C to +85°C 56 TQFN-EP** T5688-3

MAX9709ECB+* -40°C to +85°C 64 TQFP-EP** C64E-6

PKG

CODE

FS1, FS2

SYNC

RIGHT

CHANNEL

LEFT

CHANNEL

MONO

G1, G2

TH0, TH1,

TH2

2

CLASS D

GAIN

CONTROL

2

MODULATOR

STEREO MODE

3

MAX9709

OUTPUT

PROTECTION

SYNCOUT

TEMP

FS1, FS2

SYNC

AUDIO

INPUT

V

G1, G2

TH0, TH1,

TH2

DIGITAL

MONO

2

CLASS D

GAIN

CONTROL

2

MODULATOR

MONO MODE

MAX9709

OUTPUT

PROTECTION

3

SYNCOUT

TEMP

MAX9709

25W/50W, Filterless, Spread-Spectrum,
Stereo/Mono, Class D Amplifier

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= ∞, MONO = low (stereo

mode), SHDN = MUTE = high, G1 = low, G2 = high (A

V

= 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are

connected between OUT_+ and OUT_-, unless otherwise stated. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

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.

PVDD, VDDto PGND, GND .......................................-0.3 to +30V

PV

DD

to VDD..........................................................-0.3V to +0.3V

OUTR+, OUTR-, OUTL+,

OUTL- to PGND, GND..........................-0.3V to (PV

DD

+ 0.3V)

C1N to GND .............................................-0.3V to (PV

DD

+ 0.3V)

C1P to GND..............................(PV

DD

- 0.3V) to (CPVDD+ 0.3V)

CPV

DD

to GND ..........................................(PV

DD

- 0.3V) to +40V

All Other Pins to GND.............................................-0.3V to +12V

Continuous Input Current (except PV

DD

, VDD, OUTR+,

OUTR-, OUTL+, and OUTL-) ..........................................20mA

Continuous Power Dissipation (T

A

= +70°C)

56-Pin Thin QFN (derate 47.6mW/°C above +70°C) .....3.81W

64-Pin TQFP (derate 43.5mW/°C above +70°C)............3.48W

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

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

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

Thermal Resistance (θ

JC

)

56-Pin Thin QFN… ......................................................0.6°C/W

64-Pin TQFP…................................................................2°C/W

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage Range V

Shutdown Current I

Shutdown to Full Operation t

Mute to Full Operation t

Input Impedance R

Output Pulldown Resistance SHDN = GND 600 kΩ

Output Offset Voltage V

Power-Supply Rejection Ratio PSRR

Common-Mode Rejection Ratio CMRR

Switch On-Resistance R

Switching Frequency f

Oscillator Spread Bandwidth FS1 = FS2 = high (SSM) ±2 %

SYNCIN Lock Range Equal to fSW x 4 600 1200 kHz

DD

SHDN

SON

MUTE

IN

OS

DS

SW

Inferred from PSRR test 10 22 V
SHDN = low 0.1 1 µA

G1 = 0, G2 = 1 50 85 125

G1 = 1, G2 = 1 40 63 90

G1 = 1, G2 = 0 25 43 60

G1 = 0, G2 = 0 12 21 30

AC-coupled input, measured between
OUT_+ and OUT_-

PVDD = 10V to 22V 67 90

200mV

P-P

(Note 2)

DC, input referred 49 70

f = 20Hz to 20kHz, input referred 60

One power switch 0.3 0.6 Ω

FS1 FS2

0 0 180 200 220

1 1 (SSM) 200

1 0 160

0 1 250

= 1kHz 90

= 20kHz 52

ripple

f

RIPPLE

f

RIPPLE

100 ms

100 ms

3 ±40 mV

kΩ

dB

dB

kHz

MAX9709

25W/50W, Filterless, Spread-Spectrum,

Stereo/Mono, Class D Amplifier

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= ∞, MONO = low (stereo

mode), SHDN = MUTE = high, G1 = low, G2 = high (A

V

= 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are

connected between OUT_+ and OUT_-, unless otherwise stated. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Gain A

TEMP Flag Threshold T

TEMP Flag Accuracy From +80°C to +140°C ±6 °C
TEMP Flag Hysteresis 2°C

STEREO MODE (R

Quiescent Current

Output Power P

Total Harmonic Distortion Plus
Noise

Signal-to-Noise Ratio SNR P

Efficiency η P

Left-Right Channel Gain
Matching

= 8Ω, Note 3)

LOAD

V

FLAG

OUT

THD+N

G1 = 0, G2 = 1 21.6 22.0 22.3

G1 = 1, G2 = 1 24.9 25.0 25.6

G1 = 1, G2 = 0 29.2 29.5 29.9

G1 = 0, G2 = 0 35.9 36.0 36.6

TH2 TH1 TH0

000 80

001 90

0 1 0 100

0 1 1 110

1 0 0 120

1 0 1 129

1 1 0 139

111

MUTE = 1, R
MUTE = 0 6.5 13

f = 1kHz, THD =
10%, T

A

f = 1kHz, BW = 22Hz to 22kHz,
P

= 12W

OUT

= 10W

OUT

= 25W + 25W , f = 1kHz 87 %

OU T

R

= ∞ 0.2 %

LOAD

= 20V 25

= 22V 29

= 12V,

= 4Ω

22Hz to 22kHz 91

A-weighted 96

LOAD

= +25°C

= ∞ 20 33

P

VDD

P

VDD

P

VDD

R

LOAD

15

0.1 %

dB

°C

mA

W

dB

MAX9709

25W/50W, Filterless, Spread-Spectrum,
Stereo/Mono, Class D Amplifier

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= ∞, MONO = low (stereo

mode), SHDN = MUTE = high, G1 = low, G2 = high (A

V

= 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are

connected between OUT_+ and OUT_-, unless otherwise stated. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Inputs AC-coupled to GND.
Note 3: Testing performed with an 8Ω resistive load in series with a 68µH inductive load across the BTL outputs.
Note 4: Minimum output power is guaranteed by pulse testing.
Note 5: Testing performed with an 8Ω resistive load in series with a 68µH inductive load connected across BTL outputs. Mode tran-

sitions are controlled by SHDN.

Note 6: Testing performed with a 4Ω resistive load in series with a 33µH inductive load across the BTL outputs.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output Short-Circuit Current
Threshold

Click-and-Pop Level K

MONO MODE (R

Quiescent Current

Output Power P

Total Harmonic Distortion Plus
Noise

Signal-to-Noise Ratio SNR P

Efficiency η P

= 4Ω, MONO = HIGH) (Note 6)

LOAD

I

SC

CP

OUT

THD+N

R

LOAD

Peak voltage, 32
samples/second,
A-weighted (Notes 2, 5)

MUTE = 1, R
MUTE = 0 6.5

f = 1kHz,
THD = 10%

f = 1kHz, BW = 22Hz to 22kHz,

= 22W

P

OUT

= 10W

OUT

= 54W, f = 1kHz 86 %

OUT

= 0Ω 3A

= ∞ 20

LOAD

R

= 8Ω 25

LOAD

= 4Ω 50

R

LOAD

Into shutdown -63

Out of shutdown -55

20Hz to 20kHz 91

A-weighted 95

0.09 %

dBV

mA

W

dB

Output Short-Circuit Current
Threshold

Click-and-Pop Level K

DIGITAL INPUTS (SHDN, MUTE, G1, G2, FS1, FS2, TH0, TH1, TH2, SYNCIN, MONO)

Logic-Input Current I

Logic-Input High Voltage V

Logic-Input Low Voltage V

OPEN-DRAIN OUTPUTS (TEMP, SYNCOUT)

Open-Drain Output Low Voltage V

Leakage Current I

I

SC

CP

IN

IH

IL

OL

LEAK

R

= 0Ω 6A

LOAD

Peak voltage, 32
samples/second,
A-weighted (Notes 2, 5)

0 to 12V 1 µA

I

= 3mA 0.4 V

SINK

V

= 5.5V 0.2 µA

PULLUP

Into shutdown -60

dBV

Out of shutdown -63

2.5 V

0.8 V

MAX9709

25W/50W, Filterless, Spread-Spectrum,

Stereo/Mono, Class D Amplifier

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= 8Ω, SHDN = high, MONO

= low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (R

L

) are between OUT_+ and

OUT_-, T

A

= +25°C, unless otherwise stated.)

SHUTDOWN SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX9709 toc07

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (nA)

201812 14 16

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0

10 22

SHDN = 0

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (MONO MODE)

MAX9709 toc08

OUTPUT POWER (W)

THD+N (%)

5040302010

0.1

1

10

100

0.01
060

R

LOAD

= 4

Ω

f

IN

= 1kHz

THD+N (%)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (STEREO MODE)

100

fIN = 1kHz

10

1

0.1

0.01
035

OUTPUT POWER (W)

MAX9709 toc01

30252015105

EFFICIENCY vs. OUTPUT POWER

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (STEREO MODE)

100

PVDD = 12V

10

1

THD+N (%)

0.1

0.01
025

OUTPUT POWER vs. SUPPLY VOLTAGE

(STEREO MODE)

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

030

OUTPUT POWER (W)

252015105

MAX9709 toc04

OUTPUT POWER (W)

35

30

25

20

15

10

5

0

10 24

Ω

R

= 8

LOAD

Ω

R

= 4

LOAD

2015105

OUTPUT POWER (W)

(STEREO MODE)

THD+N = 10%

THD+N = 1%

222018161412

SUPPLY VOLTAGE (V)

MAX9709 toc02

0.1

THD+N (%)

0.01

24

22

MAX9709 toc05

20

18

16

SUPPLY CURRENT (mA)

14

12

10

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (STEREO MODE)

1

P

= 12W

OUT

10 100k

NO-LOAD SUPPLY CURRENT

vs. SUPPLY VOLTAGE (STEREO MODE)

TA = +85°C

10 22

10k1k100

FREQUENCY (Hz)

TA = +25°C

TA = -40°C

2018161412

SUPPLY VOLTAGE (V)

MAX9709 toc03

MAX9709 toc06

MAX9709

25W/50W, Filterless, Spread-Spectrum,
Stereo/Mono, Class D Amplifier

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= 8Ω, SHDN = high, MONO

= low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (R

L

) are between OUT_+ and

OUT_-, T

A

= +25°C, unless otherwise stated.)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

MAX9709 toc09

OUTPUT POWER (W)

THD+N (%)

2015105

0.1

1

10

100

0.01
025

PVDD = 12V,
MONO MODE,
f

IN

= 1kHz

R

L

= 4

Ω

WIDEBAND OUTPUT SPECTRUM

30

20

10

0

-10

-20

-30

-40

OUTPUT AMPLITUDE (dBV)

-50

-60

-70

(FFM MODE)

FREQUENCY (Hz)

10kHz RBW

10M1M100k 100M

TOTAL HARMONIC DISTORTION PLUS NOISE

1

0.1

THD+N (%)

0.01
10 100k

0

-20

MAX9709 toc12

-40

-60

-80

OUTPUT AMPLITUDE (dBV)

-100

-120
024

vs. FREQUENCY (MONO MODE)

Ω

R

= 4

LOAD

= 22W

P

OUT

10k1k100

FREQUENCY (Hz)

OUTPUT FREQUENCY SPECTRUM

(SSM MODE)

FREQUENCY (kHz)

WIDEBAND OUTPUT SPECTRUM

(SSM MODE)

30

20

MAX9709 toc10

10

0

-10

-20

-30

-40

OUTPUT AMPLITUDE (dBV)

-50

-60

-70
100k 100M

FREQUENCY (Hz)

10kHz RBW

MAX9709 toc11

10M1M

OUTPUT FREQUENCY SPECTRUM

(FFM MODE)

0

-20

MAX9709 toc13

-40

-60

-80

OUTPUT AMPLITUDE (dBV)

-100

20161284

-120
024

FREQUENCY (kHz)

MAX9709 toc14

20161284

MAX9709

25W/50W, Filterless, Spread-Spectrum,

Stereo/Mono, Class D Amplifier

_______________________________________________________________________________________ 7

Typical Operating Characteristics (continued)

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= 8Ω, SHDN = high, MONO

= low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (R

L

) are between OUT_+ and

OUT_-, T

A

= +25°C, unless otherwise stated.)

EFFICIENCY vs. OUTPUT POWER

OUTPUT POWER vs. SUPPLY VOLTAGE

(MONO MODE)

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

060

R

LOAD

Ω

= 4

OUTPUT POWER (W)

5040302010

70

60

MAX9709 toc15

50

40

30

OUTPUT POWER (W)

20

10

R

LOAD

= 1kHz

f

IN

0

10 24

OUTPUT POWER vs. LOAD RESISTANCE

(STEREO MODE)

30

25

THD+N = 10%

= 1kHz

f

IN

MAX9709 toc18

(MONO MODE)

Ω

= 4

THD+N = 10%

THD+N = 1%

222018161412

SUPPLY VOLTAGE (V)

MUTE RESPONSE

MAX9709 toc19

MAX9709 toc16

MUTE
5V/div

OUTPUT POWER vs. LOAD RESISTANCE

60

50

40

30

20

OUTPUT POWER (W)

10

0

412

(MONO MODE)

THD+N = 10%

= 1kHz

f

IN

1086

LOAD RESISTANCE (Ω)

SHUTDOWN RESPONSE

MAX9709 toc20

MAX9709 toc17

SHDN
5V/div

20

15

10

OUTPUT POWER PER CHANNEL (W)

5

0

716

LOAD RESISTANCE (Ω)

15141312111098

40ms/div

OUTPUT
50mV/div

40ms/div

OUTPUT
50mV/div

MAX9709

25W/50W, Filterless, Spread-Spectrum,
Stereo/Mono, Class D Amplifier

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(PVDD= VDD= +20V, PGND = GND = 0V, CSS= 0.47µF, C

REG

= 0.01µF, C1 = 0.1µF, C2 = 1µF, R

LOAD

= 8Ω, SHDN = high, MONO

= low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (R

L

) are between OUT_+ and

OUT_-, T

A

= +25°C, unless otherwise stated.)

Pin Description

COMMON-MODE REJECTION RATIO

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

-60
INPUT REFERRED

-65

-70

-75

-80

-85

CMRR (dB)

-90

-95

-100

-105

-110
10 100k

FREQUENCY (Hz)

10k1k100

MAX9709 toc21

-30

-40

-50

-60

-70

PSRR (dB)

-80

-90

-100

-110
10 100k

vs. FREQUENCY

MAX9709 toc22

10k1k100

FREQUENCY (Hz)

-40

-50

-60

-70

-80

-90

CROSSTALK (dB)

-100

-110

-120

CROSSTALK vs. FREQUENCY

10 100k

FREQUENCY (Hz)

10k1k100

MAX9709 toc23

35

30

25

20

15

10

OUTPUT POWER PER CHANNEL (W)

5

0

PIN

TQFP TQFN

1, 8, 13, 16,
17, 32, 33, 41,
48, 49, 50, 55,

58, 63, 64

2, 3, 4, 45, 46,

47, 56, 57

5, 6, 7,

42, 43, 44

MAXIMUM STEADY-STATE OUTPUT POWER

vs. TEMPERATURE (STEREO MODE)

fIN = 1kHz
TH0 = TH1 = 1
TH2 = 0

30 70

AMBIENT TEMPERATURE (°C)

605040

NAME FUNCTION

1, 12, 42, 43,

44, 55, 56

2, 3, 4, 39,

40, 41, 49, 50

5, 6, 7,

36, 37, 38

N.C. No Connection. Not internally connected.

PGND Power Ground

PV

Positive Power Supply. Bypass to PGND with a 0.1µF and a 47µF capacitor with the

DD

smallest capacitor placed as close to pins as possible.

MAX9709 toc24

MAXIMUM STEADY-STATE OUTPUT POWER

vs. TEMPERATURE (MONO MODE)*

70

60

50

40

30

OUTPUT POWER (W)

20

R

= 4

Ω

LOAD

f

= 1kHz

IN

10

TH0 = TH1 = 1
TH2 = 0

0

30

AMBIENT TEMPERATURE (°C)

*MEASURED WITH THE MAX9709EVKIT,
JUNCTION TEMPERATURE MAINTAINED AT +110°C.

605040

MAX9709 toc25

70