MAXIM MAX9723 Technical data

General Description

The MAX9723 stereo DirectDrive®headphone amplifier
with BassMax and volume control is ideal for portable
audio applications where space is at a premium and per­formance is essential. The MAX9723 operates from a sin­gle 1.8V to 3.6V power supply and includes features that
reduce external component count, system cost, board
space, and improves audio reproduction.

The headphone amplifier uses Maxim’s patented
DirectDrive architecture that produces a ground-refer­enced output from a single supply, eliminating the need
for large DC-blocking capacitors. The headphone ampli­fiers deliver 62mW into a 16Ω load, feature low 0.006%
THD+N, and high 90dB PSRR. The MAX9723 features
Maxim’s industry-leading click-and-pop suppression.

The BassMax feature boosts the bass response of the
amplifier, improving audio reproduction when using
inexpensive headphones. The integrated volume con­trol features 32 discrete volume levels, eliminating the
need for an external potentiometer. BassMax and the
volume control are enabled through the I2C/SMBus™­compatible interface. Shutdown is controlled through
either the hardware or software interfaces.

The MAX9723 consumes only 3.7mA of supply current
at 1.8V, provides short-circuit and thermal-overload
protection, and is fully specified over the extended

-40°C to +85°C temperature range. The MAX9723 is
available in a tiny (2mm x 2mm x 0.62mm) 16-bump
chip-scale package (UCSP™) or 16-pin thin QFN (4mm
x 4mm x 0.8mm) package.

Applications

Features

♦ 62mW, DirectDrive Headphone Amplifier

Eliminates Bulky DC-Blocking Capacitors

♦ 1.8V to 3.6V Single-Supply Operation

♦ Integrated 32-Level Volume Control

♦ High 90dB PSRR at 1kHz

♦ Low 0.006% THD+N

♦ Industry-Leading Click-and-Pop Suppression

♦ ±8kV HBM ESD-Protected Headphone Outputs

♦ Short-Circuit and Thermal-Overload Protection

♦ Low-Power Shutdown Mode (5µA)

♦ Software-Enabled Bass Boost (BassMax)

♦ I2C/SMBus-Compatible Interface

♦ Available in Space-Saving, Thermally Efficient

Packages:

16-Bump UCSP (2mm x 2mm x 0.62mm)
16-Pin Thin QFN (4mm x 4mm x 0.8mm)

MAX9723

Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I2C

________________________________________________________________ Maxim Integrated Products 1

I2C INTERFACE

VOLUME

CONTROL

BassMax

BassMax

1.8V TO 3.6V SUPPLY

SCL

BBL

OUTL

BBR

OUTR

SDA

INL

INR

MAX9723

Σ

Σ

Block Diagram

Ordering Information

19-3509; Rev 2; 8/08

EVALUATION KIT

AVAILABLE

PART**

PIN­PACKAGE

PKG
CODE

MAX9723_EBE-T*

B16-1

MAX9723_ETE+

16 TQFN

T1644-4

DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.

SMBus is a trademark of Intel Corp.

UCSP is a trademark of Maxim Integrated Products, Inc.

**Replace the ‘_’ with the one-letter code that denotes the
slave address and maximum programmable gain. See the
Selector Guide.

+Denotes a lead-free/RoHS-compliant package.
*Future product—contact factory for availability.

Pin Configurations appear at end of data sheet.

PDA Audio
Portable CD Players
Mini Disc Players
Automotive Multimedia

MP3-Enabled Cellular
Phones

MP3 Players

PART

SLAVE ADDRESS

MAXIMUM GAIN (dB)

MAX9723A

1001100 0

MAX9723B

1001101 0

MAX9723C

1001100 +6

MAX9723D

1001101 +6

Selector Guide

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

TEMP RANGE

-40°C to +85°C

-40°C to +85°C

16 UCSP-16

MAX9723

Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I2C

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.

SGND to PGND .....................................................-0.3V to +0.3V

V

DD

to PGND............................................................-0.3V to +4V

PV

SS

to SVSS.........................................................-0.3V to +0.3V

C1P to PGND..............................................-0.3V to (V

DD

+ 0.3V)

C1N to PGND............................................(PV

SS

- 0.3V) to +0.3V

PV

SS

, SVSSto PGND ................................................+0.3V to -4V

IN_ to SGND ..................................(SV

SS

- 0.3V) to (VDD+ 0.3V)

SDA, SCL to PGND ..................................................-0.3V to +4V

SHDN to PGND ..........................................-0.3V to (VDD+ 0.3V)

OUT_ to SGND ............................................................-3V to +3V

BB_ to SGND...............................................................-2V to +2V

Duration of OUT_ Short Circuit to _GND ....................Continuous

Continuous Current Into/Out of:

V

DD

, C1P, PGND, C1N, PVSS, SVSS, or OUT_ ..............±0.85A

Any Other Pin.................................................................±20mA

Continuous Power Dissipation (T

A

= +70°C)

4 x 4 UCSP (derate 8.2mW/°C above +70°C) ...........659.2mW

16-Pin Thin QFN (derate 16.9mW/°C above +70°C) ....1349mW

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

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

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

Bump Temperature (soldering)

Reflow ...........................................................................+230°C

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

ELECTRICAL CHARACTERISTICS

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V. gain = 0dB, maximum volume, BassMax disabled. Load connect-
ed between OUT_ and SGND where specified. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

PARAMETER

CONDITIONS

UNITS

GENERAL

Supply Voltage Range V

DD

1.8 3.6 V

Quiescent Supply Current I

DD

No load 4 6.5 mA

Shutdown Supply Current

V

SHDN

= 0V 5 8.5 µA

Turn-On Time t

ON

µs

Turn-Off Time t

OFF

35 µs

Thermal Shutdown Threshold T

THRES

°C

Thermal Shutdown Hysteresis T

HYST

12 °C

HEADPHONE AMPLIFIER

Gain = 0dB,
MAX9723A/
MAX9723B

Output Offset Voltage V

OS

M easur ed b etw een
OU T_ and S GN D
( N ote 2)

Gain = +6dB,
MAX9723C/
MAX9723D

±5

mV

Input Resistance R

IN

All volume levels 10 17 27 kΩ

BBR, BBL Input Bias Current

nA

DC, VDD = 1.8V to 3.6V 73 90

f = 217Hz, 100mV

P-P

ripple,

V

DD

= 3.0V

87

f = 1kHz, 100mV

P-P

ripple,

V

DD

= 3.0V

86

Power-Supply Rejection Ratio PSRR (Note 2)

f = 20kHz, 100mV

P-P

ripple,

V

DD

= 3.0V

61

dB

SYMBOL

MIN TYP MAX

I

DD_SHDN

200

I

BIAS_BB

+143

±0.7 ±4.5

±0.8

±10 ±100

MAX9723

Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I2C

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V. gain = 0dB, maximum volume, BassMax disabled. Load connect-
ed between OUT_ and SGND where specified. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

PARAMETER

CONDITIONS

UNITS

RL = 32Ω 59

Output Power P

OUT

THD+N = 1%,
f

IN

= 1kHz

R

L

= 16Ω (Note 5) 38 60

mW

RL = 16Ω, P

OUT

= 35mW, fIN = 1kHz

Total Harmonic Distortion Plus
Noise

RL = 32Ω, P

OUT

= 45mW, fIN = 1kHz

%

Gain range bit 5 = 1 0

MAX9723A/
MAX9723B

Gain range bit 5 = 0 -5

dB

Gain range bit 5 = 1 +6

Maximum Gain A

MAX

MAX9723C/
MAX9723D

Gain range bit 5 = 0 +1

dB

BW = 22Hz to 22kHz 99

Signal-to-Noise Ratio SNR

R

L

= 32Ω,

V

OUT

= 1V

RMS A-weighted

dB

Slew Rate SR

V/µs

Capacitive Drive No sustained oscillations

pF

Output Resistance in Shutdown

V

SHDN

= 0V, measured from OUT_ to

SGND

20 kΩ

Output Capacitance in Shutdown

V

SHDN

= 0V, measured from OUT_ to

SGND

60 pF

Into
shutdown

-69

MAX9723A/
MAX9723B

Out of
shutdown

-71

Into
shutdown

-70

Click/Pop Level K

CP

RL = 32Ω,
peak voltage,
A-weighted,
32 samples
per second
(Notes 2, 4)

MAX9723C/
MAX9723D

Out of
shutdown

-69

dB

Charge-Pump Switching
Frequency

f

CP

700 kHz

Crosstalk XTALK

L to R or R to L, f = 10kHz,
V

OUT

= 1V

P-P

, RL = 32Ω, both channels

loaded

80 dB

DIGITAL INPUTS (SHDN, SDA, SCL)

Input High Voltage V

IH

0.7 x
V

Input Low Voltage V

IL

0.3 x
V

Input Leakage Current ±1µA

DIGITAL OUTPUTS (SDA)

Output Low Voltage V

OL

IOL = 3mA 0.4 V

Output High Current I

OH

V

SDA

= V

DD

1µA

SYMBOL

R

OUT_SHDN

C

OUT_SHDN

THD+N

MIN TYP MAX

0.006

0.004

100

0.35

300

505 600

V

DD

V

DD

MAX9723

Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I2C

4 _______________________________________________________________________________________

TIMING CHARACTERISTICS

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load connect-
ed between OUT_ and SGND where specified. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C, see

Timing Diagram.) (Notes 1, 3)

PARAMETER

CONDITIONS

UNITS

Serial Clock Frequency f

SCL

0

kHz

Bus Free Time Between a STOP
and a START Condition

t

BUF

1.3 µs

START Condition Hold Time

0.6 µs

Low Period of the SCL Clock t

LOW

1.3 µs

High Period of the SCL Clock t

HIGH

0.6 µs

Setup Time for a Repeated
START Condition

t

SU:STA

0.6 µs

Data Hold Time

0 0.9 µs

Data Setup Time

ns

Maximum Rise Time of SDA and
SCL Signals

t

r

ns

Maximum Fall Time of SDA and
SCL Signals

t

f

ns

Setup Time for STOP Condition

0.6 µs

Pulse Width of Suppressed Spike

t

SP

ns

Maximum Capacitive Load for
Each Bus Line

pF

Note 1: All specifications are 100% tested at TA= +25°C. Temperature limits are guaranteed by design.
Note 2: Inputs AC-coupled to SGND.
Note 3: Guaranteed by design.
Note 4: Headphone mode testing performed with a 32Ω resistive load connected to GND. Mode transitions are controlled by

SHDN. The K

CP

level is calculated as: 20 x log [(level peak voltage during mode transition, no input signal)/(peak voltage

under normal operation at rated power)]. Units are expressed in dB.

Note 5: Output power MIN is specified at T

A

= +25°C.

SYMBOL

MIN TYP MAX

400

t

HD:STA

t

HD:DAT

t

SU:DAT

t

SU:STO

C

L_BUS

100

300

300

100

400

MAX9723

Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I2C

_______________________________________________________________________________________ 5

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. FREQUENCY

MAX9723 toc01

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

0.001
10 100k

VDD = 2.4V
R

L

= 16

Ω

P

OUT

= 10mW

P

OUT

= 25mW

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. FREQUENCY

MAX9723 toc02

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

0.001
10 100k

VDD = 2.4V
R

L

= 32

Ω

P

OUT

= 23mW

P

OUT

= 10mW

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. FREQUENCY

MAX9723 toc03

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

0.001
10 100k

VDD = 3V
R

L

= 16

Ω

P

OUT

= 37mW

P

OUT

= 20mW

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. FREQUENCY

MAX9723 toc04

FREQUENCY (Hz)

THD+N (%)

10k1k100

0.01

0.1

1

0.001
10 100k

VDD = 3V
R

L

= 32

Ω

P

OUT

= 30mW

P

OUT

= 10mW

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. OUTPUT POWER

MAX9723 toc05

OUTPUT POWER (mW)

THD+N (%)

4020

0.01

0.1

1

10

100

0.001

060

VDD = 2.4V
R

L

= 16

Ω

fIN = 1kHz

fIN = 20Hz

fIN = 10kHz

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. OUTPUT POWER

MAX9723 toc06

OUTPUT POWER (mW)

THD+N (%)

4020

0.01

0.1

1

10

100

0.001

060

VDD = 2.4V
R

L

= 32

Ω

fIN = 1kHz

fIN = 10kHz

fIN = 20Hz

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. OUTPUT POWER

MAX9723 toc07

OUTPUT POWER (mW)

THD+N (%)

80604020

0.01

0.1

1

10

100

0.001

0 100

VDD = 3V
R

L

= 16

Ω

fIN = 10kHz

fIN = 1kHz

fIN = 20Hz

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. OUTPUT POWER

MAX9723 toc08

OUTPUT POWER (mW)

THD+N (%)

80604020

0.01

0.1

1

10

100

0.001

0100

VDD = 3V
R

L

= 32

Ω

fIN = 10kHz

fIN = 1kHz

fIN = 20Hz

0

40

60

80

100

120

140

160

180

0 20406080

POWER DISSIPATION

vs. OUTPUT POWER

MAX9723 toc09

OUTPUT POWER (mW)

POWER DISSIPATION (mW)

20

VDD = 2.4V
f

IN

= 1kHz

P

OUT

= P

OUTL

+ P

OUTR

OUTPUTS IN PHASE

RL = 32Ω

RL = 16Ω

Typical Operating Characteristics

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load con­nected between OUT_ and SGND where specified. Outputs in phase, both channels loaded. T

A

= +25°C, unless otherwise noted.)

(See Functional Diagram/Typical Operating Circuit)

MAX9723

Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I2C

6 _______________________________________________________________________________________

0

100

50

200

150

250

300

0406020 80 100 120

POWER DISSIPATION

vs. OUTPUT POWER

MAX9723 toc10

OUTPUT POWER (mW)

POWER DISSIPATION (mW)

RL = 16Ω

VDD = 3V
f

IN

= 1kHz

P

OUT

= P

OUTL

+ P

OUTR

OUTPUTS IN PHASE

RL = 32Ω

OUTPUT POWER

vs. LOAD RESISTANCE

MAX9723 toc11

LOAD RESISTANCE (Ω)

OUTPUT POWER (mW)

100

10

20

30

40

50

60

70

80

0

10 1k

VDD = 2.4V
f

IN

= 1kHz

THD+N = 10%

THD+N = 1%

OUTPUT POWER

vs. LOAD RESISTANCE

MAX9723 toc12

LOAD RESISTANCE (Ω)

OUTPUT POWER (mW)

100

10

20

30

40

50

60

70

80

90

100

0

10 1k

VDD = 3V
f

IN

= 1kHz

THD+N = 10%

THD+N = 1%

OUTPUT POWER

vs. SUPPLY VOLTAGE

MAX9723 toc13

SUPPLY VOLTAGE (V)

OUTPUT POWER (mW)

3.43.22.8 3.02.2 2.4 2.62.0

10

20

30

40

50

60

70

80

90

100

0

1.8 3.6

THD+N = 10%

THD+N = 1%

fIN = 1kHz
R

L

= 16

Ω

20

40

60

80

100

120

140

0

OUTPUT POWER

vs. SUPPLY VOLTAGE

MAX9723 toc14

SUPPLY VOLTAGE (V)

OUTPUT POWER (mW)

3.43.22.8 3.02.2 2.4 2.62.01.8 3.6

THD+N = 10%

THD+N = 1%

fIN = 1kHz
R

L

= 32Ω

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

MAX9723 toc15

FREQUENCY (Hz)

PSRR (dB)

10k1k100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

-100
10 100k

RL = 32

Ω

Typical Operating Characteristics (continued)

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load con­nected between OUT_ and SGND where specified. Outputs in phase, both channels loaded. T

A

= +25°C, unless otherwise noted.)

(See Functional Diagram/Typical Operating Circuit)

MAX9723

Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I2C

_______________________________________________________________________________________ 7

CROSSTALK

vs. FREQUENCY

-100

-80

-60

-40

-20

0

-120

MAX9723 toc16

FREQUENCY (Hz)

CROSSTALK (dB)

10k1k10010 100k

VIN = 1V

P-P

RL = 32

Ω

A = 0dB

LEFT TO RIGHT

A = 0dB

RIGHT TO LEFT

A = 0dB

CROSSTALK

vs. FREQUENCY

-100

-80

-60

-40

-20

0

-120

MAX9723 toc17

FREQUENCY (Hz)

CROSSTALK (dB)

10k1k10010 100k

VIN = 1V

P-P

RL = 32

Ω

A = -10dB

LEFT TO RIGHT

A = -10dB

RIGHT TO LEFT

A = -10dB

BASS BOOST FREQUENCY

RESPONSE

-5

0

5

10

15

20

-10

MAX9723 toc18

FREQUENCY (Hz)

AMPLITUDE (dB)

10k1k10010 100k

NO LOAD
R1 = 47k

Ω

BassMax DISABLED

R2 = 36k

Ω

C3 = 0.068μF

R2 = 22k

Ω

C3 = 0.1μF

R2 = 10k

Ω

C3 = 0.22μF

GAIN FLATNESS
vs. FREQUENCY

-6

-5

-4

-3

-2

-1

0

1

-7

MAX9723 toc19

FREQUENCY (Hz)

AMPLITUDE (dB)

10k1k10010 100k

OUTPUT SPECTRUM

vs. FREQUENCY

MAX9723 toc20

FREQUENCY (kHz)

AMPLITUDE (dBV)

15105

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-140
020

RL = 32

Ω

V

DD

= 3V

f

IN

= 1kHz

CHARGE-PUMP OUTPUT VOLTAGE

vs. OUTPUT CURRENT

MAX9723 toc21

OUTPUT CURRENT (mA)

OUTPUT VOLTAGE (V)

175150125100755025

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0

-3.5
0200

NO HEADPHONE LOAD
CHARGE-PUMP LOAD
CONNECTED
BETWEEN PV

SS

AND PGND

Typical Operating Characteristics (continued)

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load con­nected between OUT_ and SGND where specified. Outputs in phase, both channels loaded. T

A

= +25°C, unless otherwise noted.)

(See Functional Diagram/Typical Operating Circuit)

MAX9723

Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I2C

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= SHDN = 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load con­nected between OUT_ and SGND where specified. Outputs in phase, both channels loaded. T

A

= +25°C, unless otherwise noted.)

(See Functional Diagram/Typical Operating Circuit)

OUTPUT POWER vs. CHARGE-PUMP

CAPACITANCE AND LOAD RESISTANCE

MAX9723 toc22

LOAD RESISTANCE (Ω)

OUTPUT POWER (mW)

403020

40

45

50

55

60

65

70

75

35

10 50

C1 = C2 = 2.2μF

C1 = C2 = 0.68μF

C1 = C2 = 1μF

VDD = 3V
f

IN

= 1kHz

THD+N = 1%

POWER-UP/POWER-DOWN

WAVEFORM

MAX9723 toc23

20ms/div

V

DD

2V/div

V

OUT

10mV/div

EXITING SHUTDOWN

MAX9723 toc24

40μs/div

V

OUT_

200mV/div

V

SHDN

2V/div

ENTERING SHUTDOWN

MAX9723 toc25

20μs/div

V

OUT_

200mV/div

V

SHDN

2V/div

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX9723 toc26

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

3.43.23.02.82.62.42.22.0

2.5

3.0

3.5

4.0

4.5

2.0

1.8 3.6

NO LOAD
INPUTS GROUNDED

SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE

SHUTDOWN CURRENT (μA)

1

2

3

4

5

6

7

8

0

MAX9723 toc27

SUPPLY VOLTAGE (V)

3.43.23.02.82.62.42.22.01.8 3.6

NO LOAD
INPUTS GROUNDED