Rainbow Electronics MAX9758 User Manual

General Description

The MAX9756/MAX9757/MAX9758 combine dual, 2.3W, bridge tied load (BTL) stereo audio power amplifiers and a DirectDriveTMheadphone amplifier in a single device. These devices feature single-supply voltage operation, shutdown mode, logic-selectable gain, a headphone sense input, a 31-step analog volume control, and industry-leading click-and-pop suppression. The headphone amplifier uses Maxim’s patent-pending DirectDrive architecture that produces a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors.

The MAX9756/MAX9757 feature automatic level control (ALC) that automatically limits output power to the speaker in the event of an overpowered output.

The MAX9756/MAX9758s’ 150mA internal linear regulator provides a complete solution for DAC- or CODECbased designs.

The MAX9756/MAX9757/MAX9758 are offered in spacesaving, thermally efficient 32-pin (5mm x 5mm x 0.8mm) and 36-pin thin QFN (6mm x 6mm x 0.8mm) packages. All devices are specified over the extended -40°C to +85°C temperature range.

Features

♦ Automatic Level Control—Protects Speakers

♦ Analog Volume Control

♦ 120mW DirectDrive Headphone Amplifiers (16Ω)

♦ 150mA Adjustable LDO

♦ Class AB, 2.3W, Stereo BTL Speaker Amplifiers

(3Ω)

♦ High 95dB PSRR

♦ Low-Power Shutdown Mode

♦ Industry-Leading Click-and-Pop Suppression

♦ Short-Circuit and Thermal Protection

♦ Beep Input

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

________________________________________________________________ Maxim Integrated Products 1

VOL

ALC

SINGLE SUPPLY 4.5V TO 5.5V

SINGLE SUPPLY 4.5V TO 5.5V SINGLE SUPPLY 4.5V TO 5.5V

1.2V TO 5V

HPS

BEEP

MAX9756

LDO

ALC

VOL

ALC

HPS

BEEP

MAX9757

ALC

VOL

1.2V TO 5V

HPS

BEEP

MAX9758

LDO

Simplified Block Diagrams

Ordering Information

Applications

PART

LDO PIN-PACKAGE

MAX9756ETX+

√√36 Thin QFN-EP**

MAX9757ETJ+*

√ — 32 Thin QFN-EP**

MAX9758ETJ+*

— √ 32 Thin QFN-EP**

19-3782; Rev 0; 8/05

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

Notebook PCs Tablet PCs Portable DVD

Players

Flat-Panel TVs PC Displays LCD Projectors Portable Audio

Note: All devices specified for -40°C to +85°C operating temperature range.

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

ALC

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= PVDD= HPVDD= CPV

= IN = +5.0V, GND = PGND = CPGND = 0, SHDN = VDD, REGEN = VDD, DR = SET = GND, C

BIAS

= 1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, speaker loads terminated between OUT_+ and OUT_-, headphone load

terminated between HP_ and GND, GAIN1 = GAIN2 = GAIN3 = VOL = 0 (A

V(SP)

= 15dB, A

V(HP)

= 0dB), TA= -40°C to +85°C, unless

otherwise noted. Typical values are at T

= +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.

Supply Voltage (VDD, PVDD, HPVDD, CPVDD, IN to GND) ....+6V

PGND, CPGND to GND ......................................................±0.3V

CPVSS, C1N, VSSto GND......................................-6.0V to +0.3V

HP_ to GND ...........................................................................±3V

Any Other Pin .............................................-0.3V to (V

+ 0.3V)

Duration of OUT_ Short Circuit to GND or PVDD........Continuous

Duration of OUT_+ Short Circuit to OUT_- .................Continuous

Duration of HP_ Short Circuit to GND,

VSS, or HPVDD.........................................................Continuous

Duration of OUT Short Circuit to GND........................Continuous

Continuous Current (PVDD, OUT_, PGND) ...........................1.7A

Continuous Current (CPVDD, C1N, CPGND, C1P, CPVSS,

VSS, HPVDD, HP_, IN, OUT).............................................0.85A

Continuous Input Current (all other pins) .........................±20mA

Continuous Power Dissipation (TA= +70°C, single-layer board)

32-Pin Thin QFN (derate 18.6mW/°C above +70°C).....1490mW

36-Pin Thin QFN (derate 20.4mW/°C above +70°C).....1633mW

Continuous Power Dissipation (TA=+70°C, multilayer board)

32-Pin Thin QFN (derate 24.9mW/°C above +70°C).....1990mW

36-Pin Thin QFN (derate 27.7mW/°C above +70°C).....2180mW

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

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

GENERAL

Supply Voltage Range

Inferred from PSRR test 4.5 5.5 V

Headphone Supply Voltage HPV

Inferred from PSRR test 3.0 5.5 V

HPS = GND, speaker mode, R

= ∞

14 29

Quiescent Supply Current I

IDD = I

VDD

HPS = 5V, headphone mode, R

= ∞

713

Shutdown Supply Current I

SHDN

SHDN = REGEN = GND 0.2 5 µA

Bias Voltage V

BIAS

2.2

Switching Time t

Gain or input switching 10 µs

Input Resistance R

INL and INR 10 20 30 kΩ

Turn-On Time t

SON

25 ms

SPEAKER AMPLIFIERS (HPS = GND)

Output Offset Voltage V

Measured between OUT_+ and OUT_-, T

= +25°C

PVDD = 4.5V to 5.5V, TA = +25°C 75 95

f = 1kHz, V

RIPPLE

= 200mV

P-P

Power-Supply Rejection Ratio (Note 2)

PSRR

f = 10kHz, V

RIPPLE

= 200mV

P-P

RL = 8Ω 0.9 1.3

RL = 4Ω 2.0

Output Power (Note 3) P

OUT

THD+N = 1%, f = 1kHz (T

= +25°C)

= 3Ω 2.3

RL = 8Ω, BTL P

OUT

= 1W, f = 1kHz

Total Harmonic Distortion Plus Noise

RL = 4Ω, BTL P

OUT

= 1W, f = 1kHz

RL = 8Ω, BTL P

OUT

= 1W, BW = 22Hz to

22kHz, unweighted

Signal-to-Noise Ratio SNR

= 8Ω, BTL P

OUT

= 1W, A weighted 95

VDD, PV

HPVDD

+ I

CPVDD

THD+N

2.43 2.65

±0.4 ±15

0.009

0.015

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

= PVDD= HPVDD= CPV

= IN = +5.0V, GND = PGND = CPGND = 0, SHDN = VDD, REGEN = VDD, DR = SET = GND, C

BIAS

= 1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, speaker loads terminated between OUT_+ and OUT_-, headphone load

terminated between HP_ and GND, GAIN1 = GAIN2 = GAIN3 = VOL = 0 (A

V(SP)

= 15dB, A

V(HP)

= 0dB), TA= -40°C to +85°C, unless

otherwise noted. Typical values are at T

= +25°C.) (Note 1)

PARAMETER

CONDITIONS

UNITS

Noise V

BW = 22Hz to 22kHz, unweighted, measured at output, input at AC GND

µV

RMS

Capacitive-Load Drive C

No sustained oscillations

Crosstalk L to R, R to L, f = 10kHz 80 dB

Slew Rate SR Measured between OUT_+ and OUT_- 1.3 V/µs

GAIN3 = 0 GAIN2 = 0 GAIN1 = 0 15

GAIN3 = 0 GAIN2 = 0 GAIN1 = 1

GAIN3 = 0 GAIN2 = 1 GAIN1 = 0 18

GAIN3 = 0 GAIN2 = 1 GAIN1 = 1

GAIN3 = 1 GAIN2 = 0 GAIN1 = 0 21

GAIN3 = 1 GAIN2 = 0 GAIN1 = 1

GAIN3 = 1 GAIN2 = 1 GAIN1 = 0

Gain (Maximum Volume Settings)

(Note 4)

VMAX

(SPKR)

GAIN3 = 1 GAIN2 = 1 GAIN1 = 1

Into shutdown

Click-and-Pop Level K

Peak voltage, 32 samples/second, A weighted (Note 5)

Out of shutdown

dBV

HEADPHONE AMPLIFIERS (HPS = VDD)

Output Offset Voltage

)

TA = +25°C ±2 ±7 mV

HPVDD = 3V to 5.5V, TA = +25°C 70 90

f = 1kHz, V

RIPPLE

= 200mV

P-P

Power-Supply Rejection Ratio (Note 2)

PSRR

f = 10kHz, V

RIPPLE

= 200mV

P-P

RL = 32Ω 40 68

Output Power (Note 3) P

OUT

THD+N = 1%, f = 1kHz (T

= +25°C)

= 16Ω

RL = 32Ω, V

OUT

= 1V

RMS

, f = 1kHz

Total Harmonic Distortion Plus Noise

RL = 16Ω, V

OUT

= 1V

RMS

, f = 1kHz

RL = 32Ω, BTL P

OUT

= 65mW,

BW = 22Hz to 22kHz, unweighted

Signal-to-Noise Ratio SNR

= 32Ω, BTL P

OUT

= 65W,

BW = 22Hz to 22kHz, A weighted

Noise V

BW = 22Hz to 22kHz

µV

RMS

Capacitive-Load Drive C

No sustained oscillations

Crosstalk L to R, R to L, f = 10kHz 60 dB

Slew Rate SR 1.4 V/µs

GAIN2 = 0, HPS = 1 0

Gain (Maximum Volume Settings) (Note 6)

)

GAIN2 = 1, HPS = 1 3.0

Into shutdown 62

Click-and-Pop Level K

Peak voltage, 32 samples/second, A weighted (Note 4)

dBV

SYMBOL

MIN TYP MAX

200

16.5

19.5

22.5

24.0

25.5

38.5

OS(HP

THD+N

VMAX(HP

130

0.02

0.04

100

20.4

200

Out of shutdown

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

= PVDD= HPVDD= CPV

= IN = +5.0V, GND = PGND = CPGND = 0, SHDN = VDD, REGEN = VDD, DR = SET = GND, C

BIAS

= 1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, speaker loads terminated between OUT_+ and OUT_-, headphone load

terminated between HP_ and GND, GAIN1 = GAIN2 = GAIN3 = VOL = 0 (A

V(SP)

= 15dB, A

V(HP)

= 0dB), TA= -40°C to +85°C, unless

otherwise noted. Typical values are at T

= +25°C.) (Note 1)

PARAMETER

CONDITIONS

UNITS

CHARGE PUMP

Charge-Pump Frequency f

OSC

kHz

VOLUME CONTROL

VOL Input Impedance R

VOL

MΩ

VOL Input Hysteresis 10 mV

Full Mute Voltage (Note 7)

0.858 x V

Full Mute Attenuation fIN = 1kHz -85 dB

Input Impedance R

VOL_

Any gain setting

MΩ

AV = +15dB to 0dB

AV = -2dB to -20dB

Channel Matching

= -22dB to -56dB

BEEP INPUT

Beep Signal Amplitude Threshold

TA = +25°C, RB = 47kΩ (see BEEP Input section)

0.3 V

Beep Signal Frequency Threshold

= +25°C

AUTOMATIC LEVEL CONTROL SPEAKER AMPLIFIER (MAX9756/MAX9757)

PREF Threshold Accuracy R

PREF

= 180kΩ 5 8.1 %

Maximum Gain Compression 6.0 6.3 dB

Attack Time CT = 1µF (Note 8) 15 ms

Hold Time Time between attack and release phases 50 ms

0V < VDR < (0.3V x VDD)30

9.5Release Time (Note 9)

= 1µF, release from 6dB

0.8V < V

< V

DR INPUT (TRI-STATE INPUT)

DR Input Voltage High V

DRH

0.8 x V

DR Input Voltage Middle V

DRM

0.4 x

0.6 x V

DR Input Voltage Low V

DRL

0.3 x V

Input Leakage Current 0V ≤ VDR ≤ V

±1 µA

LOGIC INPUTS (GAIN_, SHDN, REGEN)

Input High Voltage V

Input Low Voltage V

0.8 V

Input Leakage Current I

±1 µA

SYMBOL

MIN TYP MAX

500 550 600

100

300

HPV

100

±0.2

±0.3

±1.0

0.4V < VDR < (0.6V x VDD)

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

_______________________________________________________________________________________ 5

Note 1: All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design. Note 2: PSRR is specified with the amplifier input connected to GND through R

and CIN.

Note 3: Output power levels are measured with the TQFN’s exposed paddle soldered to the ground plane. Note 4: Speaker path gain is defined as: A

VSPKR

= (V

OUT+

- V

OUT-

)/V

IN__

Note 5: Speaker mode testing performed with 8Ω resistive load connected across BTL output. Headphone mode testing per-

formed with 32Ω resistive load connected between HP_ and GND. Mode transitions are controlled by SHDN.

Note 6: Headphone path gain is defined as: A

VHP

= V

HP_/VIN__

Note 7: See Table 3 for detains on the mute levels. Note 8: Attack envelope is exponential. Attack time is defined as the 15 x 10

x CT.

Note 9: Time for the gain to return to within 10% of nominal gain setting after the input signal has fallen below the PREF threshold.

Release is linear in dB. Release time is proportional to magnitude of gain compression.

Note 10: Dropout voltage is defined as (V

- V

OUT

) when V

OUT

is 2% below the value of V

OUT

for VIN= V

OUT(NOM)

+ 1V.

ELECTRICAL CHARACTERISTICS (continued)

= PVDD= HPVDD= CPV

= IN = +5.0V, GND = PGND = CPGND = 0, SHDN = VDD, REGEN = VDD, DR = SET = GND, C

BIAS

= 1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, speaker loads terminated between OUT_+ and OUT_-, headphone load

terminated between HP_ and GND, GAIN1 = GAIN2 = GAIN3 = VOL = 0 (A

V(SP)

= 15dB, A

V(HP)

= 0dB), TA= -40°C to +85°C, unless

otherwise noted. Typical values are at T

= +25°C.) (Note 1)

PARAMETER

CONDITIONS

UNITS

LOGIC INPUT HEADPHONE (HPS)

Input High Voltage V

Input Low Voltage V

0.8 V

HPS Pullup Current 35 µA

LOW-DROPOUT LINEAR REGULATOR

Input Voltage Range V

Inferred from line regulation 3.5 5.5 V

OUT

= 0mA, SHDN = GND

Supply (Ground) Current I

OUT

= 150mA

µA

Shutdown Current I

SHDN

REGEN = 0V 0.1 3 µA

Output Current I

OUT

Fixed Output Voltage Accuracy I

OUT

= 1mA

Adjustable Output Voltage Range

SET Reference Voltage V

SET

SET Dual-Mode Threshold

SET Input Leakage Current I

SET

OUT

= 50mA 25 50

Dropout Voltage (Note 10) ΔV

OUT

= 4.65V (fixed

output operation)

OUT

= 150mA

Output Current Limit I

LIM

Startup Time 20 µs

Line Regulation

= 3.5V to 5.5V, V

OUT

= 2.5V,

OUT

= 1mA

%/V

Load Regulation V

OUT

= 4.65V, 1mA < I

OUT

< 150mA 0.5 %

f = 1kHz 60

Ripple Rejection V

RIPPLE

= 200mV

P-P

f = 10kHz 50

Output Voltage Noise

20Hz to 22kHz, C

OUT

= 2 x 1µF,

OUT

= 150mA, V

OUT

= 4.65V

µV

RMS

SYMBOL

MIN TYP MAX

100 160

350

150

SET

1.19 1.21 1.23

200

±20 ±500

100 150

-0.1 +0.01 +0.1

300

100

±1.5

4.85

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

6 _______________________________________________________________________________________

Typical Operating Characteristics

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc01

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 5V R

= 3

OUTPUT POWER = 500mW

OUTPUT POWER = 1.8W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc02

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 5V R

= 4

OUTPUT POWER = 500mW

OUTPUT POWER = 1.5W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc03

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 5V R

= 8

OUTPUT POWER = 500mW

OUTPUT POWER = 1W

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (SPEAKER MODE)

MAX9756 toc04

OUTPUT POWER (W)

THD+N (%)

3.02.52.01.51.00.5

0.01

0.1

100

0.001

03.5

VDD = 5V R

= 3

fIN = 100Hz

fIN = 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (SPEAKER MODE)

MAX9756 toc05

OUTPUT POWER (W)

THD+N (%)

3.02.52.01.51.00.5

0.01

0.1

100

0.001 0 3.5

VDD = 5V R

= 4

fIN = 100Hz

fIN = 1kHz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (SPEAKER MODE)

MAX9756 toc06

OUTPUT POWER (W)

THD+N (%)

1.51.00.5

0.01

0.1

100

0.001 0 2.0

VDD = 5V R

= 8

fIN = 100Hz

fIN = 1kHz

fIN = 10kHz

OUTPUT POWER

vs. LOAD RESISTANCE (SPEAKER MODE)

MAX9756 toc07

LOAD RESISTANCE (Ω)

OUTPUT POWER (W)

0.5

1.0

1.5

2.0

2.5

3.0

1100

VDD = 5V f = 1kHz

THD+N = 10%

THD+N = 1%

POWER DISSIPATION vs. OUTPUT POWER

(SPEAKER MODE)

MAX9756 toc08

OUTPUT POWER (W)

POWER DISSIPATION (W)

3.53.02.52.01.51.00.5

0.5

1.0

1.5

2.0

2.5

3.0

0 4.0

f = 1kHz P

OUT

= P

OUTL

+ P

OUTR

RL = 8

RL = 4

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY (SPEAKER MODE)

MAX9756 toc09

FREQUENCY (Hz)

PSRR (dB)

10k1k100

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-120 10 100k

RIPPLE

= 200mV

P-P

RL = 8

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

_______________________________________________________________________________________ 7

CROSSTALK vs. FREQUENCY

(SPEAKER MODE)

MAX9756 toc10

FREQUENCY (Hz)

CROSSTALK (dB)

10k1k100

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-110 10 100k

LEFT TO RIGHT

RIGHT TO LEFT

VIN = 200mV

P-P

TURN-ON RESPONSE (SPEAKER MODE)

MAX9756 toc11

10ms/div

SHDN 5V/div

OUT_+ 2V/div

OUT_2V/div

OUT_+ - OUT_50mV/div

TURN-OFF RESPONSE (SPEAKER MODE)

MAX9756 toc12

10ms/div

SHDN 5V/div

OUT_+ 2V/div

OUT_2V/div

OUT_+ - OUT_50mV/div

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc13

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 5V R

= 16

OUTPUT POWER = 100mW

OUTPUT POWER = 40mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc14

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 5V R

= 32

OUTPUT POWER = 20mW

OUTPUT POWER = 60mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc15

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 3.3V R

= 16

OUTPUT POWER = 80mW

OUTPUT POWER = 20mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc16

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

0.001 10 100k

VDD = 3.3V R

= 32

OUTPUT POWER = 50mW

OUTPUT POWER = 20mW

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (HEADPHONE MODE)

MAX9756 toc17

OUTPUT POWER (mW)

THD+N (%)

18016014012010080604020

0.01

0.1

100

0.001 0200

HPVDD = 5V R

= 16

fIN = 100Hz

fIN = 10kHz

fIN = 1kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (HEADPHONE MODE)

MAX9756 toc18

OUTPUT POWER (mW)

THD+N (%)

908070605040302010

0.01

0.1

100

0.001 0100

HPVDD = 5V R

= 32

fIN = 100Hz

fIN = 10kHz

fIN = 1kHz

Typical Operating Characteristics (continued)

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (HEADPHONE MODE)

MAX9756 toc19

OUTPUT POWER (mW)

THD+N (%)

10080604020

0.01

0.1

100

0.001 0120

HPVDD = 3.3V R

= 16

fIN = 100Hz

fIN = 10kHz

fIN = 1kHz

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER (HEADPHONE MODE)

MAX9756 toc20

OUTPUT POWER (mW)

THD+N (%)

80 907040 50 60

301020

0.01

0.1

100

0.001 0 100

HPVDD = 3.3V R

= 32

fIN = 100Hz

fIN = 1kHz

fIN = 10kHz

OUTPUT POWER vs. LOAD RESISTANCE

(HEADPHONE MODE)

MAX9756 toc21

LOAD RESISTANCE (Ω)

OUTPUT POWER (mW)

100

120

140

10 1000

HPVDD = 3.3V f = 1kHz

THD+N = 10%

THD+N = 1%

OUTPUT POWER vs. LOAD RESISTANCE

(HEADPHONE MODE)

MAX9756 toc22

LOAD RESISTANCE (Ω)

OUTPUT POWER (mW)

100

120

140

160

180

200

10 1000

HPVDD = 5V f = 1kHz

THD+N = 10%

THD+N = 1%

POWER DISSIPATION vs. OUTPUT POWER

(HEADPHONE MODE)

MAX9756 toc23

OUTPUT POWER (mW)

POWER DISSIPATION (mW)

225200175150125100755025

0.2

0.4

0.6

0.8

0 250

f = 1kHz P

OUT

= PHL + P

RL = 16

RL = 32

OUTPUT POWER vs. SUPPLY VOLTAGE

(HEADPHONE MODE)

MAX9756 toc24

SUPPLY VOLTAGE (V)

OUTPUT POWER (mW)

5.04.54.03.5

100

110

120

130

140

3.0 5.5

RL = 16

RL = 32

THD+N = 1%

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY (HEADPHONE MODE)

MAX9756 toc25

FREQUENCY (Hz)

PSRR (dB)

10k1k100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100 10 100k

RIPPLE

= 100mV

P-P

INPUTS AC-GROUNDED

HPVDD = 5V

HPVDD = 3.3V

CROSSTALK vs. FREQUENCY

(HEADPHONE MODE)

MAX9756 toc26

FREQUENCY (Hz)

CROSSTALK (dB)

1010.1

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-110

0.01 100

RL = 32

f = 1kHz V

= 200mV

P-P

RIGHT TO LEFT

LEFT TO RIGHT

OUTPUT POWER vs. CHARGE-PUMP CAPACITANCE (HEADPHONE MODE)

MAX9756 toc27

LOAD (Ω)

OUTPUT POWER (mW)

3025

35 40

40 30

100

120

110

130

140

150

10 50

C1 = C2 = 1μF

C1 = C2 = 2.2μF

f = 1kHz THD+N = 1%

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

_______________________________________________________________________________________ 9

TURN-ON RESPONSE (HEADPHONE MODE)

MAX9756 toc28

10ms/div

SHDN 5V/div

HPR 10mV/div

HPL 10mV/div

TURN-OFF RESPONSE (HEADPHONE MODE)

MAX9756 toc29

10ms/div

SHDN 5V/div

HPR 10mV/div

HPL 10mV/div

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX9756 toc30

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.35.14.94.7

4.5 5.5

HPS = GND

HPS = V

SHUTDOWN CURRENT

vs. SUPPLY VOLTAGE

MAX9756 toc31

SUPPLY VOLTAGE (V)

SHUTDOWN CURRENT (nA)

5.35.14.7 4.9

100

200

300

400

500

600

4.5 5.5

POWER LIMITING OF SINE BURST

(FAST ATTACK AND FAST RELEASE)

MAX9756 toc32

10ms/div

OUTPUT 2V/div

CT 1V/div

POWER LIMITING OF SINE BURST

(FAST ATTACK AND SLOW RELEASE)

MAX9756 toc33

40ms/div

OUTPUT 2V/div

CT 1V/div

POWER LIMITING OF SINE BURST

(SLOW ATTACK AND SLOW RELEASE)

MAX9756 toc33

2s/div

OUTPUT 2V/div

CT 1V/div

LDO OUTPUT VOLTAGE ACCURACY

vs. LOAD CURRENT

MAX9756 toc35

LOAD CURRENT (mA)

DEVIATION (%)

12510025 50 75

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0 0150

Typical Operating Characteristics (continued)

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

LDO OUTPUT VOLTAGE ACCURACY

vs. TEMPERATURE

MAX7956 toc37

TEMPERATURE (°C)

DEVIATION (%)

603510-15

-4

-3

-2

-1

-5

-40 85

DROPOUT VOLTAGE

vs. LOAD CURRENT

MAX9756 toc38

LOAD CURRENT (mA)

DROPOUT VOLTAGE (V)

125100755025

-200

-100

100

200

300

-300 0150

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY (LDO)

MAX9756 toc39

FREQUENCY (Hz)

PSRR (dB)

10k1k100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100 10 100k

RIPPLE

= 100mV

P-P

LDO OUTPUT NOISE

MAX9756 toc40

200μs/div

LDO_OUT 1mV/div

CROSSTALK vs. FREQUENCY

(LDO)

MAX9756 toc36

FREQUENCY (Hz)

CROSSTALK (dB)

1010.1

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-110

0.01 100

RL = 4

OUT(SPK)

= 1W

OUT

= 90mA

OUT

= 10mA

OUT

= 50mA

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 11

Typical Operating Characteristics (continued)

(VDD= PVDD= HPVDD= CPVDD= IN = +5.0V, GND = PGND = CPGND = 0V, SHDN = VDD, REGEN = DR = SET = GND, C

BIAS

1µF, C

PVSS

= 1µF, C1 = C2 = 1µF, PREF = unconnected, GAIN1 = 1, GAIN2 = GAIN3 = VOL = 0V, measurement BW = 22Hz to

22kHz, TA = +25°C, unless otherwise noted.)

OUTPUT NOISE

vs. FREQUENCY (LDO)

MAX9756 toc41

FREQUENCY (Hz)

NOISE (μV)

10k1k100

100

110

10 100k

OUT

= 2μF

10Hz TO 100kHz

LINE-TRANSIENT RESPONSE

MAX9756 toc42

40μs/div

500mV/div

4.5V

5.5V

LDO_OUT 20mV/div

LOAD-TRANSIENT RESPONSE

MAX9756 toc43

20μs/div

50V

LOAD

25mV/div

LDO_OUT = 4.65V 20mV/div

LDO SHUTDOWN RESPONSE

MAX9756 toc44

100ms/div

REGEN 5V/div

LDO_OUT 1V/div

Pin Description

MAX9756

NAME

FUNCTION

1 32 32 INL Left-Channel Audio Input

211

Gain Control Input 1

322

Gain Control Input 2

433

Gain Control Input 3

544

Audible Alert Beep Input

6, 22 5, 21 5, 21

Power Ground

766

Left-Channel Positive Speaker Output

877

Left-Channel Negative Speaker Output

9,19 8,18 8, 18

Speaker Amplifier Power Supply. Bypass with 1µF ceramic capacitor to PGND.

MAX9757 MAX9758

GAIN1

GAIN2

GAIN3

BEEP

PGND

OUTL+

OUTL-

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

12 ______________________________________________________________________________________

Pin Description (continued)

MAX9756

FUNCTION

10 9 9

Charge-Pump Power Supply. Bypass with 1µF ceramic capacitor to CPGND.

11 10 10 C1P

Charge-Pump Flying-Capacitor Positive Terminal. Connect a 1µF capacitor from C1P to C1N.

12 11 11

Charge-Pump Ground

13 12 12 C1N

Charge-Pump Flying-Capacitor Negative Terminal. Connect a 1µF capacitor from C1P to C1N.

14 13 13

Charge-Pump Negative Output. Connect to VSS.

15 14 14 V

Headphone Amplifier Negative Power Supply. Bypass with 1µF ceramic capacitor to GND.

16 15 15 HPR Right Headphone Output

17 16 16 HPL Left Headphone Output

18 17 17

Headphone Positive Power Supply. Bypass with 1µF ceramic capacitor to GND.

20 19 19

Right-Channel Negative Speaker Output

21 20 20

Right-Channel Positive Speaker Output

23 22 22 HPS

H ead p hone S ense Inp ut. Leave H P S unconnected i f autom ati c head p hone sensi ng i s not used .

24 — 23

LD O E nab l e. C onnect RE GE N to V

D D

to enab l e the LD O. C onnect to G N D to

d i sab l e LD O.

25 23 — DR

Automatic Level Control Attack to Release Time Ratio Select. Hardwired to VDD,

GND, or BIAS to set the attack to release ratio; see the ALC section.

26 24 24

Common-Mode Bias Voltage. Bypass with a 1.0µF capacitor to GND.

27 25 25

Shutdown Input. Drive SHDN low to disable the audio amplifiers. Connect SHDN to V

for normal operation.

28 26 26 VOL Analog Volume Control Input

29 27 —

P ow er - Li m i ti ng Inp ut. C onnect a r esi stor fr om P RE F to G N D to set the sp eaker outp ut cl am p i ng l evel . Leave P RE F unconnected to d i sab l e ALC ; see the ALC secti on.

30 — 27 SET

Regulator Feedback Input. Connect to GND for 4.65V fixed output. Connect to

resistor-divider for adjustable output; see the Low-Dropout Linear Regulator section.

31 28 28

Ground

32 29 — V

Power Supply

33 — — IN LDO Input. Bypass with two 1µF ceramic capacitors to GND.

34 — 30

LDO Output. Bypass with two 1µF ceramic capacitors to GND.

35 30 — CT

Automatic Level Control Attack and Release Timing Capacitor. Connect CT to GND to disable ALC; see the ALC section.

36 31 31 INR Right-Channel Audio Input

— — 29 V

Power-Supply and LDO Input. Bypass with two 1µF ceramic capacitors to GND.

EP EP EP EP

Exposed Pad. The external pad lowers the package’s thermal impedance by providing a direct-heat conduction path from the die to the PC board. Connect the

exposed thermal pad to GND.

MAX9757 MAX9758

NAME

CPV

CPGND

CPV

HPV

OUTR-

OUTR+

REGEN

BIAS

SHDN

PREF

GND

OUT

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 13

Detailed Description

The MAX9756/MAX9757/MAX9758 combine dual, 2W BTL stereo audio power amplifiers with a DirectDrive headphone amplifier in a single device. The stereo power amplifiers deliver up to 2.3W per channel into a 3Ω speaker from a 5V supply and the stereo headphone amplifiers deliver up to 130mW per channel into a 16Ω headphone from a 5V supply.

The MAX9756/MAX9757 feature ALC that automatically controls output power to the speaker, preventing loudspeaker, overload and provides optimized dynamic range.

The MAX9756/MAX9757/MAX9758 feature 31-step analog volume control and a BEEP input. The amplifier gain is pin programmable. These devices feature clickand-pop suppression, eliminating the need for discrete muting circuitry. Speaker and headphone outputs have short-circuit and thermal protection.

The MAX9756/MAX9758s’ internal LDO features Maxim’s Dual Mode™ feedback. The LDO output voltage is either fixed at 4.65V (SET = GND), or adjusted between 1.23V and 5V using a resistive divider at SET. The LDO delivers up to 150mA of continuous current, and can be enabled independently from the audio amplifiers. Short-circuit and thermal-overload protection are provided for the LDO.

All devices feature a single-supply voltage, a shutdown mode, logic-selectable gain, and a headphone sense input. Industry-leading click-and-pop suppression eliminates audible transients during power and shutdown cycles.

Each signal path consists of an input amplifier that sets the signal-path gain and feeds both the speaker and headphone amplifiers (Figure 1). The speaker amplifier uses a BTL architecture, doubling the voltage drive to the speakers and eliminating the need for DC-blocking capacitors. The output consists of two signals, identical in magnitude, but 180° out of phase.

The headphone amplifiers use Maxim’s patented DirectDrive architecture that eliminates the bulky output DC-blocking capacitors required by traditional headphone amplifiers. A charge pump inverts the positive supply (CPVDD), creating a negative supply (CPVSS). The headphone amplifiers operate from these bipolar supplies with their outputs biased about GND (Figure 2).

The amplifiers have almost twice the supply range compared to other single-supply amplifiers, nearly quadrupling the available output power. The benefit of the GND bias is that the amplifier outputs do not have a DC component (typically VDD/2). This eliminates the large DC-blocking capacitors required with conventional headphone amplifiers, conserving board space and system cost while improving frequency response.

OUT_+

OUT_-

VOLUME

CONTROL

BIAS

IN_

VOL

BIAS

HP_

GND

ALC

Figure 1. MAX9756/MAX9757 Signal Path

-V

GND

CONVENTIONAL DRIVER-BIASING SCHEME

DirectDrive BIASING SCHEME

VDD/2

GND

OUT

Figure 2. Traditional Headphone Amplifier Output Waveform vs. DirectDrive Headphone Amplifier Output Waveform

Dual Mode is a trademark of Maxim Integrated Products, Inc.

MAX9756/MAX9757/MAX9758

The MAX9756/MAX9757/MAX9758 feature an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop suppression that eliminates audible transients on startup and shutdown. The amplifiers include thermal-overload and short-circuit protection. An additional feature of the amplifiers is that there is no phase inversion from input to output.

Automatic Level Control (ALC)

Two-watt amplifiers are commonly used in notebook PCs (almost always powered from a 5V supply). With an 8Ω speaker driven from a BTL amplifier, the maximum theoretical continuous power available is:

See Figure 5 for suggested ALC component values. The ALC feature offers two benefits:

1) To limit amplifier power to protect a loudspeaker.

2) To make input signals with a wide dynamic range more intelligible by boosting low-level signals without distorting the high-level signals.

A device without ALC experiences clipping at the output when too much gain is applied to the input. ALC prevents clipping at the output when too much gain is

applied to the input, eliminating output clipping. Figure 3 shows a comparison of an overgained speaker input with and without ALC.

The MAX9756/MAX9758 control the gain to the speakers by first detecting that the output voltage to the speaker has exceeded a preset limit. The speaker amplifier gain is rapidly reduced to correct for the excessive output power. This process is known as the attack time. When the signal subsequently lowers in amplitude, the gain is held at the reduced state for a short period before slowly increasing to the normal value. This process is known as the hold and release time. The speed at which the amplifiers adjust to changing input signals is set by the external timing capacitor C

and the setting of logic input DR. The output power limit can be set by adjusting the value of the external resistor connected to PREF. Gain reduction is a function of input signal amplitude with a maximum ALC attenuation of 6dB. Figure 4 shows the effect of an input burst exceeding the preset limit, output attack, hold and release times.

This process (referred to as “limiting” in audio) limits the amplifier output power so loudspeaker overload can be prevented. If the attack and release times are configured to respond too fast, audible artifacts often, described as “pumping” or “breathing,” can occur as the gain is rapidly adjusted to follow the dynamics of the signal. For best results, adjust the time constant of the ALC to accommodate the source material. Notebook applications in which music CDs and DVDs are the main audio source, a 495µs attack time with a 990ms release time is recommended with a 1.2W output into an 8Ω load.

OUT

PEAK

SPEAKER

⎛

⎝

⎜

⎞

⎠

⎟

⎛

⎝

⎜ ⎜ ⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟ ⎟ ⎟

⎛

⎝

⎜

⎞

⎠

⎟

⎛

⎝

⎜ ⎜ ⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟ ⎟ ⎟

2 8

156

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

14 ______________________________________________________________________________________

ALC DISABLE, CLIPPING AT THE OUTPUT

INPUT

SIGNAL

10ms/div

OUTPUT

SIGNAL

ALC ENABLE, NO CLIPPING AT THE OUTPUT

Figure 3. ALC Disabled vs. ALC Enabled

Attack Time

The attack time is the time it takes to reduce the gain after the input signal has exceeded the threshold level. Suggested attack time range is from 150µs to 50ms. The gain attenuation in attack is exponential and the attack time is defined as one time constant. The time constant of the attack is given by 15,000 x C

sec-

onds (where CCTis the external timing capacitor).

• Use a short attack time for the ALC to react quickly to transient signals, such as snare drum beats (music) or gun shots (DVD). Fast attack times can lead to gain “pumping” where rapid ALC action can be heard reacting to dynamic material.

• Use a longer attack time to allow the ALC to ignore short-duration peaks and only reduce the gain when a noticeable increase in loudness occurs. Short-duration peaks are not reduced, but louder passages are.

This allows the louder passages to be reduced in volume, thereby maximizing output dynamic range. Having the attack time too long can possibly result in some damage to the loudspeaker under harsh conditions.

Hold Time

Hold time is the delay after the signal falls below the threshold level before the release phase is initiated. Hold time is internally set to 50ms and nonadjustable. The hold time is cancelled by any signal exceeding the set threshold level and attack is reinitiated.

Release Time

The release time is how long it takes for the gain to return to its normal level after the input signal has fallen below the threshold level and 50ms hold time has expired. Release time is defined as release from a 6dB gain compression to 10% of the nominal gain setting after the input signal has fallen below PREF threshold and the 50ms hold time has expired. Release time is adjustable between 95ms and 10s. The release time is set by picking an attack time using CCTand setting the attack to release time ratio by configuring DR as shown in Table 2. Release time is linear in dB with time and is inversely proportional to the magnitude of gain compression:

• Use a small ratio to maximize the speed of the ALC.

• Use a large ratio to maximize the sound quality and prevent repeated excursions above the threshold from being independently adjusted by the ALC.

Release and attack times are set by selecting the capacitance value between CT and GND, and by setting the logic state of DR (Table 1). DR is a tristate logic input that sets the attack-to-release time ratio. A fixed hold time of 50ms is internally added to the release time.

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 15

OUTPUT 2V/div

CT 1V/div

10ms/div

Figure 4. Attack, Hold, and Release Time

Table 1. Attack and Release Time

ATTACK TIME RELEASE TIME

TIMING CAPACITOR

)

DR = ‘X’ DR = V

DR = V

BIAS

DR = GND

10nF 150µs 30ms 95ms 300ms

33nF 495µs 99ms 313ms 990ms

100nF 1.5ms 300ms 950ms 3s

330nF 4.95ms 990ms 3.1s 9.9s

1µF 15ms 3s 9.5s —

2.2µF 33ms 6.6s — —

3.3µF 49.5ms 10s — —

MAX9756/MAX9757/MAX9758

The release/attack time ratio that can be achieved by programming DR is listed in Table 2.

Output Power Threshold

To set the threshold at which speaker output is clamped, an external resistor must be connected from PREF to ground. The suggested external resistor range is from 100kΩ to 200kΩ (for best results use a 1% resistor). Leaving PREF unconnected disables the ALC function. A constant current of 12µA is sourced at PREF, so that a 180kΩ resistor results in 1.2W clamp

limit on an 8Ω load and a 200kΩ resistor results in a

1.5W clamp limit on an 8Ω load (Figure 6).

Use the following equation to choose the value for R

PREF

for the desired maximum output power level

based on a sine wave input:

Gain Selection

The MAX9756/MAX9757/MAX9758 feature an internally set, selectable gain. The GAIN1, GAIN2, and GAIN3 inputs set the maximum gain for the speaker and headphone amplifiers (Table 3). The gain of the device can vary based upon the voltage at VOL but does not exceed the maximum gain listed below (see the Analog Volume (VOL) Control section).

PREF

OUT L

⎛

⎝

⎜

⎞

⎠

⎟

⎛

⎝

⎜

⎞

⎠

⎟

⎛

⎝

⎜ ⎜

⎞

⎠

⎟ ⎟

180

1 166 8

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

16 ______________________________________________________________________________________

MAX9756

MAX9757

33nF

180kΩ

VALUES SHOWN FOR AN OUTPUT POWER THRESHOLD OF 1.2W WITH AN R

= 8Ω ATTACK TIME OF 495μs AND A RELEASE TIME OF 990ms

PREF

Figure 5. Recommended Output Power Threshold, Attack, and Release Time Components

OUTPUT POWER THRESHOLD

vs. R

PREF

(kΩ)

OUTPUT POWER THRESHOLD (W)

190180170160150140130120110

0.5

1.0

1.5

2.0

2.5

3.0

100 200

RL = 4Ω

RL = 8Ω

Figure 6. Output Power Threshold vs. R

PREF

Table 2. Release to Attack Ratio

DR RELEASE/ATTACK RATIO

200

BIAS

633

GND 2000

Table 3. Maximum Gain Settings

GAIN3 GAIN2 GAIN1 SPEAKER MODE GAIN (dB) HEADPHONE MODE GAIN (dB)

0 0 0 +15 0

0 0 1 +16.5 0

0 1 0 +18 +3

0 1 1 +19.5 +3

1 0 0 +21 0

1 0 1 +22.5 0

1 1 0 +24 +3

1 1 1 +25.5 +3

Analog Volume Control (VOL)

The MAX9756/MAX9757/MAX9758 feature an analog volume control that varies the gain of the device in 31 discrete steps based upon the DC voltage applied to VOL (see Table 4). The input range of VOL is from 0 (full volume) to HPVDD(full mute), with example step sizes shown in Table 3. Connect the reference of the device driving VOL (Figure 7) to HPVDD. Connect VOL to GND (full volume) if volume control is not used.

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 17

Table 4. Volume Levels

VOL

(V) = MULTIPLIER x

HPV

SPEAKER MODE

GAIN (dB)

HEADPHONE MODE

GAIN (dB)

M U L TIPLIE R

VOL

(

)

VOL

(

)

GA I N 3 = 0

GA I N 3 = 1

0.07

15 16.5 18 19.5 21 22.5 24 25.5 0 3

0.16

14 16 17.5 19 20 22 23.5 25 -1 2.5

0.18

13 15 17 18.5 19 21 23 24.5 -2 2

0.21

12 14 16.5 18 18 20 22.5 24 -3 1.5

0.23

10 13 16 17.5 16 19 22 23.5 -5 1

0.25

812151714182123-70

0.28

6 10 14 16.5 12 16 20 22.5 -9 -1

0.30

4 8 13 16 10 14 19 22 -11 -2

0.32

2 6 12 15 8 12 18 21 -13 -3

0.35

0 4 10 14 6 10 16 20 -15 -5

0.37

-2 2 8 13 4 8 14 19 -17 -7

0.39

-4 0 6 12 2 6 12 18 -19 -9

0.42

-6 -2 4 10 0 4 10 16 -21 -11

0.44

-8 -4 2 8 -2 2 8 14 -23 -13

0.46

-10 -6 0 6 -4 0 6 12 -25 -15

0.49

-12 -8 -2 4 -6 -2 4 10 -27 -17

0.51

-14 -10 -4 2 -8 -4 2 8 -29 -19

0.54

-16 -12 -6 0 -10 -6 0 6 -31 -21

0.56

-18 -14 -8 -2 -12 -8 -2 4 -33 -23

0.58

-20 -16 -10 -4 -14 -10 -4 2 -35 -25

0.61

-22 -18 -12 -6 -16 -12 -6 0 -37 -27

0.63

-24 -20 -14 -8 -18 -14 -8 -2 -39 -29

0.65

-26 -22 -16 -10 -20 -16 -10 -4 -41 -31

0.68

-28 -24 -18 -12 -22 -18 -12 -6 -43 -33

0.70

-32 -26 -20 -14 -26 -20 -14 -8 -47 -35

0.72

-36 -28 -22 -16 -30 -22 -16 -10 -51 -37

0.75

-40 -32 -24 -18 -34 -26 -18 -12 -55 -39

0.77

-44 -36 -26 -20 -38 -30 -20 -14 -59 -41

0.79

-48 -40 -28 -22 -42 -34 -22 -15 -63 -43

0.82

-52 -44 -32 -24 -46 -38 -26 -18 -67 -47

0.84

-56 -48 -36 -26 -50 -42 -30 -20 -71 -51

0.93

MUTE

Figure 7. Volume Control Circuit

*Based on HPV

= 3.3V.

X = Don’t care.

MAX

GA I N 2 = 0

GA I N 1 = 0

MIN

0.00 0.49

0.49 0.57

0.57 0.64

0.64 0.72

0.72 0.80

0.80 0.88

0.88 0.95

0.95 1.03

1.03 1.11

1.11 1.19

1.19 1.26

1.26 1.34

1.34 1.42

1.42 1.50

1.50 1.57

1.57 1.65

1.65 1.73

1.73 1.80

1.80 1.88

1.88 1.96

1.96 2.04

2.04 2.11

2.11 2.19

2.19 2.27

2.27 2.35

2.35 2.42

2.42 2.50

2.50 2.58

2.58 2.66

2.66 2.73

2.73 2.81

2.81 3.30 MUTE MUTE

GA I N 3 = 0

GA I N 2 = 0

GA I N 1 = 1

GA I N 3 = 0

GA I N 2 = 1

GA I N 1 = 0

GA I N 3 = 0

GA I N 2 = 1

GA I N 1 = 1

MAX9756

HPV

REF

DAC

VOL

GA I N 3 = 1

GA I N 2 = 0

GA I N 1 = 0

MUTE MUTE MUTE MUTE MUTE MUTE MUTE

GA I N 2 = 0

GA I N 1 = 1

GA I N 3 = 1

GA I N 2 = 1

GA I N 1 = 0

GA I N 3 = 1

GA I N 2 = 1

GA I N 1 = 1

GA I N 3 = X

GA I N 2 = 0

GA I N 1 = X

GA I N 3 = X

GA I N 2 = 1

GA I N 1 = X

MAX9756/MAX9757/MAX9758

Since the volume control (VOL) ADC is ratiometric to HPVDD, any variations in HPVDDare negated. The gain step sizes are not constant; the step sizes are

0.5dB/step at the upper extreme, 2dB/step in the midrange, and 4dB/step at the lower extreme. Figure 8 shows the transfer function of the volume control for a

3.3V supply.

Low-Dropout Linear Regulator

The MAX9756/MAX9758s’ low-dropout linear regulator (LDO) can be used to provide a clean power supply to a CODEC or other circuitry. The LDO can be enabled independently of the audio amplifiers. REGEN enables/disables the LDO, set REGEN = VDDto enable the LDO or set REGEN = GND to disable. The LDO is capable of providing up to 150mA continuous current and features Maxim’s Dual Mode feedback. When SET is connected to GND, the output is internally set to approximately 4.65V. Adjust the output from 1.23V to 5V by connecting two external resistors, used as a voltage-divider, at SET (Figure 9).

The output voltage is set by the following equation:

where V

SET

= 1.23V.

To simplify resistor selection:

Since the input bias current at SET is nominally zero, large resistance values can be used for R1 and R2 to minimize power consumption without losing accuracy. Up to 1.5MΩ is acceptable for R2.

To minimize the current consumption, it is desirable to use high-value resistors (> 10kΩ for the external feed- back divider (R1, R2). The input capacitance at SET and the stray and wiring capacitance should be compensated by placing a small capacitor (in the 10pF range) across the upper feedback resistor R1 (see Figure 9).

This capacitor creates a zero in the feedback loop to reduce overshoot. Overcompensation can cause poor stability in the high current range.

The regulator should be compensated with two 1µF ceramic capacitors connected between IN and GND and OUT and GND. X7R dielectric with 10% tolerance is recommended.

The ESR of each capacitor should not exceed 40mΩ for good stability up to the full-rated current (150mA). Place the capacitors as close as possible to the device to limit the parasitic resistance and inductance. There is no upper limit to the amount of additional bypass capacitance.

DirectDrive Headphone Amplifier

Unlike the MAX9756/MAX9757/MAX9758, conventional single-supply headphone amplifiers typically have their outputs biased at half the supply voltage for maximum dynamic range. Large coupling capacitors are needed to block this DC bias from the headphones. Without these capacitors, a significant amount of DC current flows to the headphone, resulting in unnecessary power dissipation and possible damage to both headphone and headphone amplifier.

OUT

SET

12 1=

⎛

⎝

⎜

⎞

⎠

⎟

−

R R

OUT SET

⎛ ⎝

⎜

⎞ ⎠

⎟

1 2

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

18 ______________________________________________________________________________________

Figure 8. Volume Control Transfer Function

VOLUME CONTROL TRANSFER FUNCTION

VOL

(V)

GAIN (dB)

3.53.02.52.01.51.00.5

-60

-40

-20

-80 0 4.0

GAIN1 = GAIN2 = GAIN3 = 1 HPV

= 3.3V

SPEAKER MODE

HEADPHONE MODE

Figure 9. Adjustable Output Using External Feedback Resistors

MAX9756

MAX9758

OUT

SET

GND

1μF

10pF

Maxim’s patent-pending DirectDrive architecture uses a charge pump to create an internal negative supply voltage. This allows the MAX9756/MAX9757/MAX9758 headphone amplifier output to be biased at GND, almost doubling the dynamic range while operating from a single supply. With no DC component, there is no need for the large DC-blocking capacitors. Instead of two large capacitors (220µF, typ), the MAX9756/MAX9757/ MAX9758 charge pump requires only two small ceramic capacitors (1µF typ), conserving board space, reducing cost, and improving the frequency response of the headphone amplifier. See the Output Power vs. ChargePump Capacitance graph in the Typical Operating Characteristics for details of the possible capacitor values.

Low-Frequency Response

In addition to the cost and size disadvantages, the DCblocking capacitors limit the low-frequency response of the amplifier. The impedance of the headphone load to the DC-blocking capacitor forms a highpass filter with the -3dB point determined by:

where R

is the impedance of the headphone and

OUT

is the value of the DC-blocking capacitor.

The highpass filter is required by conventional singleended, single-supply headphone amplifiers to block the midrail DC component of the audio signal from the headphones. Depending on the -3dB point, the filter can attenuate low-frequency signals within the audio band.

Larger values of C

OUT

reduce the attenuation but are physically larger, more expensive capacitors. Figure 10 shows the relationship between the size of C

OUT

and

the resulting low-frequency attenuation. Note that the

-3dB point for a 16Ω headphone with a 100µF-blocking capacitor is 100Hz, well within the audio band.

Charge Pump

The MAX9756/MAX9757/MAX9758 feature a low-noise inverting charge pump to generate the negative rail necessary for DirectDrive headphone operation. The switching frequency is well beyond the audio range, and does not interfere with the audio signals. The switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. Limiting the switching speed of the charge pump minimizes the di/dt noise caused by the parasitic bond wire and trace inductance.

Headphone Sense Input (HPS)

The headphone sense input (HPS) monitors the headphone jack and automatically configures the MAX9756/ MAX9757/MAX9758 based upon the voltage applied at HPS. A voltage of less than 0.8V enables the speaker amplifier. A voltage of greater than 2V disables the speaker amplifiers and enables the headphone amplifiers. For automatic headphone detection, connect HPS to the control pin of a 3-wire headphone jack as shown in Figure 11. With no headphone present, the output impedance of the headphone amplifier pulls HPS low. When a headphone plug is inserted into the jack, the control pin is disconnected from the tip contact and HPS is pulled to VDDwith 35µA.

fdB

L OUT

−=3

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 19

-15.0 10 100 1k 10k 100k

LOW-FREQUENCY ROLLOFF

= 16Ω)

-12.0

-13.5

-6.0

-7.5

-9.0

-10.5

-3.0

-4.5

-1.5

FREQUENCY (Hz)

ATTENUATION (dB)

DirectDrive

330μF

220μF

100μF

33μF

Figure 10. Low-Frequency Attenuation of Common DCBlocking Capacitor Values

MAX9756/ MAX9757/

MAX9758

14kΩ

35μA

14kΩ

HPS HPL

HPR

SHUTDOWN

CONTROL

Figure 11. HPS Configuration

MAX9756/MAX9757/MAX9758

BIAS

The MAX9756/MAX9757/MAX9758 feature an internally generated, power-supply independent, common-mode bias voltage of 2.5V referenced to GND. BIAS provides both click-and-pop suppression and sets the DC bias level for the amplifiers. Choose the value of the bypass capacitor as described in the BIAS Capacitor section. No external load should be applied to BIAS. Any load lowers the BIAS voltage, affecting the overall performance of the device.

BEEP Input

The MAX9756/MAX9757/MAX9758 feature an audible alert beep input (BEEP) that accepts a mono system alert signal and mixes it into the stereo audio path. When the amplitude of V

BEEP

exceeds 300mV

P-P

and the frequency of the beep signal is greater than 300Hz, the beep signal is mixed into the active audio path (speaker or headphone). If the signal at V

BEEP

is either

< 300mV

P-P

or < 300Hz, the BEEP signal is not mixed into the audio path. The amplitude of the BEEP signal at the device output is roughly the amplitude V

BEEP

times

the gain of the selected signal path.

The input resistor (RB) sets the gain of the BEEP input amplifier, and thus the amplitude of V

BEEP

. Choose R

based on:

The total BEEP gain is given by:

where 47kΩ is the value of the BEEP amplifier feedback resistor, V

BEEP

is the BEEP amplifier output, V

IN(BEEP)

is the BEEP input amplitude, and V

OUT(BEEP)

is the total

BEEP output signal. A

V(BEEPOUT

) is given by the values

listed in Table 5. Note that V

BEEP

must be higher than

300mV

P-P

. The BEEP amplifier can be set up as either an attenuator, if the original alert signal amplitude is too large, or to gain up the alert signal if it is below 300mV

P-P

. AC-couple the alert signal to BEEP. Choose the value of the coupling capacitor as described in the Input Filtering section. Multiple beep inputs can be summed (Figure 12).

OUT BEEP

IN BEEP B

V BEEPOUT

()

⎛

⎝

⎜

⎞

⎠

⎟

47 Ω

IN BEEP

BEEP

()

≤

× 47 Ω

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

20 ______________________________________________________________________________________

MAX9756/ MAX9757/

MAX9758

47kΩ

BEEP

0.47μF

SOURCE 3

47kΩ

0.47μF

SOURCE 2

47kΩ

0.47μF

SOURCE 1

47kΩ

BIAS

WINDOW

DETECTOR

(0.3V

P-P

THRESHOLD)

FREQUENCY

DETECTOR

(300Hz THRESHOLD)

SPEAKER/HEADPHONE

AMPLIFIER INPUTS

BEEP

Figure 12. Beep Input

Table 5. BEEP Output Gain

V(BEEPOUT)

HEADPHONE *

(V/V)

SPEAKER*

(V/V)

GAIN1

1.5 8.4 0 0 0

1.5 9.4 0 0 1

1.78 10 0 1 0

1.78 10 0 1 1

1.5 15.8 1 0 0

1.5 18.8 1 0 1

1.78 20 1 1 0

1.78 20 1 1 1

*All output gains are for V

VOL

= GND.

GAIN3 GAIN2

Shutdown (

SHDN

)

The MAX9756/MAX9757/MAX9758 feature a 0.2µA, low-power shutdown mode that reduces quiescent current consumption and extends battery life. Driving SHDN low disables the drive amplifiers, bias circuitry, and charge pump, and drives BIAS and all outputs to GND. Connect SHDN to VDDfor normal operation.

Click-and-Pop Suppression

Speaker Amplifier

The MAX9756/MAX9757/MAX9758 speaker amplifiers feature Maxim’s comprehensive, industry-leading clickand-pop suppression. During startup, the click-andpop suppression circuitry eliminates any audible transient sources internal to the device. When entering shutdown, both amplifier outputs ramp to GND quickly and simultaneously.

Headphone Amplifier

In conventional single-supply headphone amplifiers, the output-coupling capacitor is a major contributor of audible clicks and pops. Since the MAX9756/MAX9757/ MAX9758 do not require output-coupling capacitors, no audible transient occurs.

Additionally, the MAX9756/MAX9757/MAX9758 feature extensive click-and-pop suppression that eliminates any audible transient sources internal to the device. The Turn-On/Turn-Off waveforms in the Typical Operating Characteristics show that there are minimal spectral components in the audible range at the output upon startup and shutdown.

Applications Information

BTL Speaker Amplifiers

The MAX9756/MAX9757/MAX9758 feature speaker amplifiers designed to drive a load differentially, a configuration referred to as bridge-tied load (BTL). The BTL configuration (Figure 13) offers advantages over the single-ended configuration, where one side of the load is connected to ground. Driving the load differentially doubles the output voltage compared to a single-ended amplifier under similar conditions.

Since the differential outputs are biased at 2.5V, there is no net DC voltage across the load. This eliminates the need for DC-blocking capacitors required for singleended amplifiers. These capacitors can be large and expensive, can consume board space, and can degrade low-frequency performance.

Power Dissipation and Heat Sinking

Under normal operating conditions, the MAX9756/ MAX9757/MAX9758 can dissipate a significant amount of power. The maximum power dissipation for each

package is given in the Absolute Maximum Ratings under Continuous Power Dissipation, or can be calculated by the following equation:

where T

J(MAX)

is +150°C, TAis the ambient temperature,

and θJAis the reciprocal of the derating factor in °C/W as specified in the Absolute Maximum Ratings section. For example, θJAof the 32-pin thin QFN package is +40.2°C/W. For optimum power dissipation, the exposed paddle of the package should be connected to the ground plane (see the Layout and Grounding section).

Output Power (Speaker Amplifier)

The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. The maximum power dissipation for a given VDDand load is given by the following equation:

If the power dissipation for a given application exceeds the maximum allowed for a given package, either reduce V

, increase load impedance, decrease the ambient temperature, or add heatsinking to the device or setting PREF to limit output power to a safe level. Large output, supply, and ground PC board traces improve the maximum power dissipation in the package. Thermal-overload protection limits total power dissipation in these devices. When the junction temperature exceeds +160°C, the thermal-protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by 15°C. This results in a pulsing output under continuous thermal-overload conditions as the device heats and cools.

DISS MAX

()

DISSPKG MAX

J MAX T

()

=−

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 21

Figure 13. Bridge-Tied Load Configuration

OUT(P-P)

2 x V

OUT(P-P)

-1

MAX9756/MAX9757/MAX9758

Output Power (Headphone Amplifier)

The headphone amplifiers have been specified for the worst-case scenario—when both inputs are in phase. Under this condition, the drivers simultaneously draw current from the charge pump, leading to a slight loss in headroom of VSS. In typical stereo audio applications, the left and right signals have differences in both magnitude and phase, subsequently leading to an increase in the maximum attainable output power. Figure 14 shows the two extreme cases for in and out of phase. In reality, the available power lies between these extremes.

Power Supplies

The MAX9756/MAX9757/MAX9758 have different supplies for each portion of the device, allowing for the optimum combination of headroom and power dissipation and noise immunity. The speaker amplifiers are powered from PVDD. PVDDranges from 4.5V to 5.5V. The headphone amplifiers are powered from HPVDDand VSS. HPVDDis the positive supply of the headphone amplifiers and ranges from 3V to 5.5V. VSSis the negative supply of the headphone amplifiers. Connect VSSto CPVSS. The charge pump is powered by CPVDD. CPVDDranges from 3V to 5.5V and should be the same potential as HPVDD. The charge pump inverts the voltage at CPVDD, and the resulting voltage appears at CPVSS. The remainder of the device is powered by VDD.

Component Selection

Input Filtering

The input capacitor (C

), in conjunction with the amplifier input resistance (RIN), forms a highpass filter that removes the DC bias from an incoming signal (see the Typical Application Circuit). The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero source impedance, the -3dB point of the highpass filter is given by:

RINis the amplifier’s internal input resistance value given in the Electrical Characteristics. Choose CINsuch that f

-3dB

is well below the lowest frequency of interest.

Setting f

-3dB

too high affects the amplifier’s low-frequency response. Use capacitors with low-voltage coefficient dielectrics, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low frequencies.

BIAS Capacitor

BIAS is the output of the internally generated DC bias voltage. The BIAS bypass capacitor, C

BIAS

, improves PSRR and THD+N by reducing power supply and other noise sources at the common-mode bias node, and also generates the startup/shutdown DC bias waveforms for the speaker amplifiers. Bypass BIAS with a 1µF capacitor to GND.

Charge-Pump Capacitor Selection

Use capacitors with an ESR less than 100mΩ for optimum performance. Low-ESR ceramic capacitors minimize the output resistance of the charge pump. For best performance over the extended temperature range, select capacitors with an X7R dielectric. Table 6 lists suggested manufacturers.

IN IN

−

2π

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

22 ______________________________________________________________________________________

OUTPUT POWER (mW)

THD+N (%)

160140100 12060

0.01

0.1

100

0.001 0 200

180

HPVDD = 5V R

= 16Ω

OUTPUTS 180° OUT OF PHASE

OUTPUTS IN PHASE

Figure 14. Total Harmonic Distortion Plus Noise vs. Output Power with Inputs In/Out of Phase (Headphone Mode)

Table 6. Suggested Capacitor Manufacturers

SUPPLIER PHONE FAX WEBSITE

Taiyo Yuden 800-384-2496 800-925-0899 www.t-yuden.com

TDK 807-803-6100 847-390-4405 www.component.tdk.com

Flying Capacitor (C1)

The value of the flying capacitor (C1) affects the load regulation and output resistance of the charge pump. A C1 value that is too small degrades the device’s ability to provide sufficient current drive, which leads to a loss of output voltage. Increasing the value of C1 improves load regulation and reduces the charge-pump output resistance to an extent. See the Output Power vs. ChargePump Capacitance graph in the Typical Operating Characteristics. Above 2.2µF, the on-resistance of the switches and the ESR of C1 and C2 dominate.

Output Capacitor (C2)

The output capacitor value and ESR directly affect the ripple at CPVSS. Increasing the value of C2 reduces output ripple. Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. Lower capacitance values can be used in systems with low maximum output power levels. See the Output Power vs. Charge-Pump Capacitance graph in the Typical Operating Characteristics.

CPVDDBypass Capacitor

The CPVDDbypass capacitor (C3) lowers the output impedance of the power supply and reduces the impact of the MAX9756/MAX9757/MAX9758’s charge-pump switching transients. Bypass CPVDDwith C3, the same value as C1, and place it physically close to CPVDDand PGND (refer to the MAX9756/MAX9757/MAX9758 Evaluation Kit for a suggested layout).

Powering Other Circuits

from a Negative Supply

An additional benefit of the MAX9756/MAX9757/ MAX9758 is the internally generated negative supply voltage (CPVSS). CPVSSis used by the MAX9756/ MAX9757/MAX9758 to provide the negative supply for the headphone amplifiers. It can also be used to power other devices within a design. Current draw from CPVSSshould be limited to 5mA; exceeding this affects the operation of the headphone amplifier. A typical application is a negative supply to adjust the contrast of LCD modules.

When considering the use of CPVSSin this manner, note that the charge-pump voltage of CPVSSis roughly proportional to CPVDDand is not a regulated voltage.

Layout and Grounding

Proper layout and grounding are essential for optimum performance. Use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance, as well as route heat away from the device. Good grounding improves audio performance, minimizes crosstalk between channels, and prevents any switching noise from coupling into the audio signal. Connect CPGND, PGND, and GND together at a single point on the PC board. Route CPGND and all traces that carry switching transients away from GND, PGND, and the traces and components in the audio signal path.

Connect all components associated with the charge pump (C2 and C3) to the CPGND plane. Connect V

and CPVSStogether at the device. Place the chargepump capacitors (C1, C2, and C3) as close to the device as possible. Bypass HPV

and PVDDwith a 1µF capacitor to GND. Place the bypass capacitors as close to the device as possible.

Use large, low-resistance output traces. As load impedance decreases, the current drawn from the device outputs increase. At higher current, the resistance of the output traces decrease the power delivered to the load.

For example, when compared to a 0Ω trace, a 100mΩ trace reduces the power delivered to a 4Ω load from

2.1W to 2W. Large output, supply, and GND traces also improve the power dissipation of the device. The MAX9756/MAX9757/MAX9758 thin QFN package features an exposed thermal pad on its underside. This pad lowers the package’s thermal resistance by providing a direct-heat conduction path from the die to the PC board. Connect the exposed thermal pad to GND by using a large pad and multiple vias to the GND plane.

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 23

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

24 ______________________________________________________________________________________

MAX9756 Block Diagram

HPV

HPS

INR

BIAS

VOL

GAIN1

GAIN2

BEEP

3V TO 5.5V

CPV

C1P

C1N

1μF

BIAS

1μF

0V TO

HPV

1μF

0.47μF

1μF

CPGND

INL

CPV

REGEN

31 6, 22

OUT

4.65V OUTPUT TO CODEC

SET

PREF

1μF

3V TO 5.5V

HPL

HPR

MAX9756

0.1μF0.1

GAIN/

VOLUME

CONTROL

BTL

AMPLIFIER

RIGHT-

CHANNEL

AUDIO INPUT

OUTR+

OUTR-

CHARGE

PUMP

VOLUME AND GAIN CONTROL

HEADPHONE

DETECTION

SHUTDOWN

CONTROL

BEEP

DETECTION

GAIN/

VOLUME

BTL

AMPLIFIER

LEFT-CHANNEL

AUDIO INPUT

OUTL+

4.5V TO 5.5V

OUTL-

PEAK

DETECT

GAIN3

SHDN

9, 19

100μF

4.5V TO 5.5V

47k

FIGURE SHOWN WITH AN ATTACK TIME = 495μs, RELEASE TIME = 990ms AND AN OUTPUT POWER LIMIT SET TO 1.2W, SPKR GAIN = 25.5dB, LDO SHOWN IN FIXED OUTPUT MODE, HPGAIN = 3dB.

0.033μF

1μF

GND PGND

LDO

C3, C4

1μF

1μF1μF

180k

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 25

MAX9757 Block Diagram

HPV

HPS

INR

BIAS

VOL

GAIN1

GAIN2

BEEP

3V TO 5.5V

CPV

C1P

C1N

1μF

BIAS

1μF

0V TO

HPV

1μF

0.47μF

1μF

CPGND

INL

CPV

28 5, 21

1μF

3V TO 5.5V

HPL

HPR

MAX9757

0.1μF 0.1μF

GAIN/

VOLUME

CONTROL

BTL

AMPLIFIER

RIGHT-

CHANNEL

AUDIO INPUT

OUTR+

OUTR-

CHARGE

PUMP

VOLUME

AND GAIN

CONTROL

HEADPHONE

DETECTION

SHUTDOWN

CONTROL

BEEP

DETECTION

GAIN/

VOLUME

BTL

AMPLIFIER

LEFT-CHANNEL

AUDIO INPUT

OUTL+

4.5V TO 5.5V

OUTL-

PEAK

DETECT

GAIN3

SHDN

8, 18

100μF

4.5V TO 5.5V

47k

FIGURE SHOWN WITH AN ATTACK TIME = 495μs, RELEASE TIME = 990ms AND AN OUTPUT POWER LIMIT SET TO 1.2W, SPKR GAIN = 25.5dB, HP GAIN = 3dB.

100μF

180k

1μF

GND PGND

PREF

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

26 ______________________________________________________________________________________

MAX9758 Block Diagram

HPV

HPS

INR

BIAS

VOL

GAIN1

GAIN2

BEEP

3V TO 5.5V

CPV

C1P

C1N

1μF

BIAS

1μF

0V TO

HPV

1μF

0.47μF

1μF

CPGND

INL

CPV

REGEN

28 5, 21

OUT

SET

1μF

3V TO 5.5V

HPL

HPR

MAX9758

0.1μF0.1

VOLUME

BTL

AMPLIFIER

RIGHT-CHANNEL

AUDIO INPUT

OUTR+

OUTR-

CHARGE

PUMP

VOLUME AND GAIN CONTROL

HEADPHONE

DETECTION

SHUTDOWN

CONTROL

BEEP

DETECTION

VOLUME

BTL

AMPLIFIER

LEFT-CHANNEL

AUDIO INPUT

OUTL+

4.5V TO 5.5V

OUTL-

GAIN3

SHDN

8, 18

100μF

4.5V TO 5.5V

FIGURE SHOWN WITH SPKR GAIN = 25.5dB, LDO SHOWN IN ADJUSTABLE OUTPUT MODE SET TO 3.3V, HP GAIN = 3dB.

1μF

GND PGND

LDO

1μF

82k

47kΩ

1μF

3.3V OUTPUT TO CODEC

10pF

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 27

System Diagram

CODEC

3V TO 5.5V

MAX9756

INR

4.5V TO 5.5V 3V TO 5.5V

INL

CPV

REGEN

OUT

BEEP

1μF

180kΩ

1μF

0.033μF

0.1μF

1μF

μC

C1P

C1N

PREF

BIAS

GND PGND

SHDN

OUTL+

OUTL-

VOL

CPV

SET

BIAS

OUTR+

GAIN1

GAIN2

OUTR-

HPL

HPS HPR

HPV

10μF

CPGND

HPV

1μF

47kΩ

GAIN3

1μF

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

28 ______________________________________________________________________________________

Pin Configurations

242322

20 19

HPV

HPL

CPV

C1P

CPV

C1N CPGND

HPR

SET

GND

OUT

INR

VOL

BEEP

PGND

OUTL+

GAIN3

GAIN2

GAIN1

INL

BIASDRREGEN

HPS

PGND

OUTR+

OUTR-

SHDN

TQFN

6mm x 6mm

MAX9756

TOP VIEW

456

OUTL-

PREF

MAX9757

THIN QFN

5mm x 5mm

GAIN2

BEEP

PGND

OUTL+

OUTL-

GAIN1

PGND

OUTR+

BIAS

OUTR-

GND

4567

2324 22 20 19 18

CPV

C1N

CPGND

GAIN3

HPS

INR

C1P

INL

CPV

PREF

HPR

VOL

HPL

HPV

SHDN

MAX9758

THIN QFN

5mm x 5mm

GAIN2

BEEP

PGND

OUTL+

OUTL-

GAIN1

REGEN

PGND

OUTR+

BIAS

OUTR-

GND

4567

2324 22 20 19 18

OUT

CPV

C1N

CPGND

GAIN3

HPS

INR

C1P

INL

CPV

SET

HPR

VOL

HPL

HPV

SHDN

Chip Information

PROCESS: BICMOS

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

______________________________________________________________________________________ 29

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages

QFN THIN.EPS

(ND-1) X e

PIN # 1 I.D.

(NE-1) X e

E/2

0.08 C

0.10 C

DETAIL A

E2/2

0.10 M C A B

PIN # 1 I.D.

0.35x45°

D/2

D2/2

e e

DETAIL B

AAAAA

MARKING

21-0140

PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm

-DRAWING NOT TO SCALE-

e/2

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive Headphone Amplifiers with Automatic Level Control

30 ______________________________________________________________________________________

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages

COMMON DIMENSIONS

MAX.

EXPOSED PAD VARIATIONS

NOM.MIN.

MIN.

NOM. MAX.

PKG. CODES

1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.

2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.

3. N IS THE TOTAL NUMBER OF TERMINALS.

4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.

5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN

0.25 mm AND 0.30 mm FROM TERMINAL TIP.

6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.

7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.

8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.

9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR T2855-3 AND T2855-6.

NOTES:

SYMBOL

PKG.

10. WARPAGE SHALL NOT EXCEED 0.10 mm.

JEDEC

0.70 0.800.75

4.90

0.25

0.250--

WHHB

0.350.30

5.10

5.105.00

0.80 BSC.

5.00

0.05

0.20 REF.

0.02

MIN. MAX.NOM.

16L 5x5

0.30 0.500.40

---

WHHC

5.00

0.30

0.55

0.65 BSC.

0.45

0.25

4.90

0.25

0.65

5.10

0.35

20L 5x5

0.20 REF.

0.75

0.02

NOM.

0.70

MIN.

0.05

0.80

MAX.

---

WHHD-1

5.00

0.25

0.55

0.50 BSC.

0.45

0.25

4.90

0.20

0.65

5.10

0.30

28L 5x5

0.20 REF.

0.75

0.02

NOM.

0.70

MIN.

0.05

0.80

MAX.

---

WHHD-2

5.00

0.40

0.50 BSC.

0.30

0.25

4.90

0.50

5.10

32L 5x5

0.20 REF.

0.75

0.02

NOM.

0.70

MIN.

0.05

0.80

MAX.

0.20 0.25 0.30

DOWN BONDS

ALLOWED

YES3.103.00 3.203.103.00 3.20T2055-3

3.103.00 3.203.103.00 3.20

T2055-4

T2855-3 3.15 3.25 3.35 3.15 3.25 3.35

T2855-6

3.15 3.25 3.35 3.15 3.25 3.35

T2855-4 2.60 2.70 2.80 2.60 2.70 2.80 T2855-5 2.60 2.70 2.80 2.60 2.70 2.80

T2855-7 2.60 2.70

2.80

2.60 2.70 2.80

3.20

3.00 3.10T3255-3 3 .203.00 3.10

3.203.00 3.10T3255-4 3 .203.00 3.10

NO NO

YES YES

YES

3.203.00T1655-3 3.10 3.00 3.10 3.20 NO NO3.203.103.003.10T1655N-1 3.00 3.20

3.353.15T2055-5 3.25 3.15 3.25 3.35

YES

3.35

3.15

T2855N-1

3.25 3.15 3.25 3.35

3.353.15T2855-8 3.25 3.15 3.25 3.35

YES

3.203.10T3255N-1 3.00

3.203.103.00

0.40

** **

** ** ** ** **

** **

SEE COMMON DIMENSIONS TABLE

±0.15

11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.

21-0140

PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm

-DRAWING NOT TO SCALE-

12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY.

3.30T4055-1 3.20 3.40 3.20 3.30 3.40

YES

0.050 0.02

0.600.40 0.50

-----

0.30 40 10

0.40 0.50

5.10

4.90 5.00

0.25 0.35 0.45

0.40 BSC.

0.15

4.90

0.250.20

5.00 5.10

0.20 REF.

0.70

MIN.

0.75 0.80

NOM.

40L 5x5

MAX.

13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", ±0.05.

T1655-2

YES3.203.103.003.103.00 3.20

T3255-5 YES3.003.103.00

3.20

3.203.10

exceptions

MAX9756/MAX9757/MAX9758

2.3W Stereo Speaker Amplifiers and DirectDrive

Headphone Amplifiers with Automatic Level Control

Quijano

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

31 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages

(NE-1) X

D/2

A1 A2

(ND-1) X

E2/2

e e

PACKAGE OUTLINE 36, 40, 48L THIN QFN, 6x6x0.8m

21-0141

QFN THIN.EPS

D2/2

NOTES:

1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.

2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.

3. N IS THE TOTAL NUMBER OF TERMINALS.

5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP.

6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.

7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.

8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.

9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT FOR 0.4mm LEAD PITCH PACKAGE T4866-1.

10. WARPAGE SHALL NOT EXCEED 0.10

11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.

12. NUMBER OF LEADS SHOWN FOR REFERENCE

mm.

ONLY.

PACKAGE OUTLINE 36, 40, 48L THIN QFN, 6x6x0.8m

21-0141

Rainbow Electronics MAX9758 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual