Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - Audio amplifier Headphones (2-channel, stereo) Class AB TQFN 16 (4x4)

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 DirectDrive archi-

tecture that produces a ground-referenced output from a

single supply, eliminating the need for large DCblocking

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 I

C/SMBus™-compatible

interface. Shutdown is controlled through either the hard-

ware 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 tem-

perature 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)

● I

C/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)

Pin Configurations appears at end of data sheet.

19-3509; Rev 3; 7/14

● PDA Audio

● Portable CD Players

● Mini Disc Players

● MP3-Enabled Cellular

● Phones

● MP3 Players

**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.

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.

PART SLAVE ADDRESS MAXIMUM GAIN (dB)

MAX9723A 1001100 0

MAX9723B 1001101 0

MAX9723C 1001100 +6

MAX9723D 1001101 +6

PART** TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX9723_EBE-T* -40°C to +85°C 16 UCSP-16 B16-1

MAX9723_ETE+ -40°C to +85°C 16 TQFN T1644-4

C INTERFACE

VOLUME

CONTROL

BassMax

1.8V TO 3.6V SUPPLY

SCL

BBL

OUTL

BBR

OUTR

SDA

INL

INR

∑

MAX9723

MAX9723 Stereo DirectDrive Headphone Amplifier

with BassMax, Volume Control, and I

Block Diagram

Ordering Information

Selector Guide

EVALUATION KIT AVAILABLE

Summary of content (26 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C 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.
PAGE 2
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Absolute Maximum Ratings SGND to PGND .....................................................-0.3V to +0.3V VDD to PGND...........................................................-0.3V to +4V PVSS to SVSS.......................................................-0.3V to +0.3V C1P to PGND.............................................-0.3V to (VDD + 0.3V) C1N to PGND...........................................(PVSS - 0.3V) to +0.
PAGE 3
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Electrical 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. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Timing 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. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, see Timing Diagram.
PAGE 5
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C 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. TA = +25°C, unless otherwise noted.) (See Functional Diagram/Typical Operating Circuit) POUT = 10mW 0.01 0.1 POUT = 10mW 0.01 100 1k 0.
PAGE 6
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C 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. TA = +25°C, unless otherwise noted.
PAGE 7
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C 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. TA = +25°C, unless otherwise noted.
PAGE 8
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C 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. TA = +25°C, unless otherwise noted.) (See Functional Diagram/Typical Operating Circuit) C1 = C2 = 2.
PAGE 9
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Pin Description PIN BUMP THIN QFN UCSP 1 D1 2 3 NAME FUNCTION VDD Power-Supply Input. Bypass VDD to PGND with a 1µF capacitor. C1 C1P Charge-Pump Flying Capacitor Positive Terminal B1 PGND 4 A1 C1N Charge-Pump Flying Capacitor Negative Terminal 5 B2 SCL Serial Clock Input. Connect a 10kI pullup resistor from SCL to VDD. 6 A2 PVSS Charge-Pump Output. Connect to SVSS.
PAGE 10
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C VDD VDD/2 GND CONVENTIONAL AMPLIFIER BIASING SCHEME +VDD SGND -VDD DirectDrive BIASING SCHEME Figure 1. Traditional Amplifier Output vs. MAX9723 DirectDrive Output MAX9723A and MAX9723B have a maximum amplifier gain of 0dB while the MAX9723C and MAX9723D have a maximum gain of +6dB. Amplifier volume is digitally programmable to any one of 32 levels.
PAGE 11
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Click-and-Pop Suppression The output-coupling capacitor is a major contributor of audible clicks and pops in conventional single-supply headphone amplifiers. The amplifier charges the coupling capacitor to its output bias voltage at startup. During shutdown the capacitor is discharged. This charging and discharging results in a DC shift across the capacitor, which appears as an audible transient at the speaker.
PAGE 12
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C SDA tBUF tSU, STA tSU, DAT tHD, STA tHD, DAT tLOW tSP tSU, STO SCL tHIGH tHD, STA tR tF START CONDITION REPEATED START CONDITION STOP CONDITION START CONDITION Figure 3. 2-Wire Serial-Interface Timing Diagram master, typically a microcontroller, generates SCL and initiates data transfer on the bus. A master device communicates to the MAX9723 by transmitting the proper address followed by the data word.
PAGE 13
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C S Sr P CLOCK PULSE FOR ACKNOWLEDGMENT START CONDITION SCL SCL 1 2 8 9 NOT ACKNOWLEDGE SDA SDA ACKNOWLEDGE Figure 4. START, STOP, and REPEATED START Conditions Figure 5. Acknowledge Table 1. MAX9723 Address Map Table 3.
PAGE 14
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Table 5. MAX9723A and MAX9723B Maximum Gain Control COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION B7 B6 B5 B4 B3 B2 B1 B0 ACKNOWLEDGE FROM MAX9723 S SLAVE ADDRESS 0 ACK COMMAND BYTE ACK P ACKNOWLEDGE FROM MAX9723 R/W Figure 6. Write Data Format Example The MAX9723A and MAX9723B have a maximum gain setting of -5dB or 0dB, while the MAX9723C and MAX9723D have a maximum gain setting of +1dB or +6dB.
PAGE 15
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Table 7. MAX9723A and MAX9723B Gain Settings (B5 = 1, Max Gain = 0dB) Table 8. MAX9723A and MAX9723B Gain Settings (B5 = 0, Max Gain = -5dB) B4 B3 B2 B1 B0 (LSB) GAIN (dB) B4 B3 B2 B1 B0 (LSB) GAIN (dB) 1 1 1 1 1 0 1 1 1 1 1 -5 1 1 1 1 0 -0.5 1 1 1 1 0 -6 1 1 1 0 1 -1 1 1 1 0 1 -7 1 1 1 0 0 -1.
PAGE 16
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Table 9. MAX9723C and MAX9723D Gain Settings (B5 = 1, Max Gain = +6dB) Table 10. MAX9723C and MAX9723D Gain Settings (B5 = 0, Max Gain = +1dB) B4 B3 B2 B1 B0 (LSB) GAIN (dB) B4 B3 B2 B1 B0 (LSB) GAIN (dB) 1 1 1 1 1 6 1 1 1 1 1 1 1 1 1 1 0 5.5 1 1 1 1 0 0 1 1 1 0 1 5 1 1 1 0 1 -1 1 1 1 0 0 4.5 1 1 1 0 0 -3 1 1 0 1 1 4 1 1 0 1 1 -5 1 1 0 1 0 3.
PAGE 17
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C MAX9723A AND MAX9723B TRANSFER FUNCTION (B5 = 1) 10 10 6 AV (dB) -20 -30 2 0 -2 -6 -8 0 6 12 18 24 -10 30 10 1 CODE -20 -10 -30 -20 GAIN (dB) 0 -40 -50 -30 -40 -60 -50 -70 -60 -80 -70 6 12 18 10k 24 MAX9723C AND MAX9723D TRANSFER FUNCTION (B5 = 0) 10 -10 0 1k Figure 9.
PAGE 18
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C GAIN PROFILE WITH AND WITHOUT BassMax 10 fPOLE 8 6 fZERO WITH BassMax 4 AV (dB) is disabled, can have an on-resistance as high as 300Ω. Choose a value for R1 that is greater than 40kΩ to ensure that positive feedback is negligible when BassMax is disabled. Table 12 contains a list of R2 values, with R1 = 47kΩ, and the corresponding lowfrequency gain.
PAGE 19
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C MAX9723 10 R 9 8 R 7 OUT_ CA RA BassMax ENABLE AV (dB) AUDIO INPUT FREQUENCY RESPONSE OF FIGURE 12 6 5 MAX9723A CMD REGISTER CODE = 0xFF RA = 47kΩ RB = 22kΩ CA = 0.33mF 4 3 2 BB_ 1 RB 0 0.1 1 10 100 1k 10k FREQUENCY (Hz) Figure 12. Using BassMax to Increase MAX9723’s Maximum Gain Table 12. BassMax Gain Examples (R1 = 47kΩ) Figure 13.
PAGE 20
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Functional Diagram/Typical Operating Circuit 1.8V TO 3.6V ANALOG INPUT R5 10kΩ C5 1µF VDD SCL R6 10kΩ SDA CIN 0.47µF INR R VDD I2C INTERFACE R SHDN VDD OUTR R3 47kΩ SVSS SVSS MAX9723 VDD BBR R4 22kΩ VDD VDD BBL C1P C1 1µF C1N CHARGE PUMP SGND PGND SVSS PVSS SVSS C2 1µF INL CIN 0.47µF R SVSS R2 22kΩ C4 0.1µF C3 0.1µF R1 47kΩ OUTL R BASS BOOST CIRCUIT TUNED FOR +8.8dB AT 106Hz.
PAGE 21
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C System Diagram 1.8V TO 3.6V R6 10kΩ R5 10kΩ C5 1µF VDD SDA I2C MASTER SCL CIN 0.47µF CIN 0.47µF CODEC OUTL INL BBL MAX9723 R4 22kΩ INR C4 0.1µF OUTR C1P C1 1µF R3 47kΩ C1N BBR C2 1µF PVSS SVSS PGND SGND R1 47kΩ C3 0.
PAGE 22
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
PAGE 23
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. www.maximintegrated.
PAGE 24
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. www.maximintegrated.
PAGE 25
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. www.maximintegrated.
PAGE 26
MAX9723 Stereo DirectDrive Headphone Amplifier with BassMax, Volume Control, and I2C Revision History REVISION REVISION NUMBER DATE PAGES CHANGED DESCRIPTION 2 8/08 Updated TQFN pin configuration, and corrected Typical Operating Circuit and System Diagram pin names 3 7/14 Removed automotive reference in Applications section 20, 21 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.