Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - Audio amplifier 1-channel (mono) Class D TDFN 10 EP (3x3)

General Description

The MAX9705 3rd-generation, ultra-low EMI, mono, Class

D audio power amplifier provides Class AB performance

with Class D efficiency. The MAX9705 delivers 2.3W into

a 4Ω load and offers efficiencies above 85%. Active

emissions limiting (AEL) circuitry greatly reduces EMI by

actively controlling the output FET gate transitions under

all possible transient output-voltage conditions. AEL pre-

vents high-frequency emissions resulting from conven-

tional Class D free-wheeling behavior in the presence of

an inductive load. Zero dead time (ZDT) technology

maintains state-of-the-art efficiency and THD+N perfor-

mance by allowing the output FETs to switch simultane-

ously without cross-conduction. A spread-spectrum

modulation scheme eliminates the need for output filter-

ing found in traditional Class D devices. These design

concepts reduce an application’s component count and

extend battery life.

The MAX9705 offers two modulation schemes: a fixed-

frequency (FFM) mode and a spread-spectrum (SSM)

mode that further reduces EMI-radiated emissions due to

the modulation frequency. The MAX9705 oscillator can

be synchronized to an external clock through the SYNC

input, allowing the switching frequency to be externally

defined. The SYNC input also allows multiple MAX9705s

to be cascaded and frequency locked, minimizing inter-

ference due to clock intermodulation. The device utilizes

a fully differential architecture, a full-bridged output, and

comprehensive click-and-pop suppression. The gain of

the MAX9705 is set internally (MAX9705A: 6dB,

MAX9705B: 12dB, MAX9705C: 15.6dB, MAX9705D:

20dB), further reducing external component count.

The MAX9705 is available in 10-pin TDFN (3mm x 3mm x

0.8mm), and 12-bump UCSP™ (1.5mm x 2mm x 0.6mm)

packages. The MAX9705 is specified over the extended

-40°C to +85°C temperature range.

Applications

Features

♦ Filterless Amplifier Passes FCC-Radiated

Emissions Standards with 24in of Cable

♦ Unique Spread-Spectrum Mode and Active

Emissions Limiting (AEL) Achieves Better than

20dB Margin Under FCC Limits

♦ Zero Dead Time (ZDT) H-Bridge Maintains State-

of-the-Art Efficiency and THD+N

♦ Simple Master-Slave Setup for Stereo Operation

♦ Up to 90% Efficiency

♦ 2.3W into 4Ω (1% THD+N)

♦ Low 0.02% THD+N (P

OUT

= 1W, V

= 5.0V)

♦ High PSRR (75dB at 217Hz)

♦ Integrated Click-and-Pop Suppression

♦ Low Quiescent Current (5.4mA)

♦ Low-Power Shutdown Mode (0.3µA)

♦ Short-Circuit and Thermal-Overload Protection

♦ Available in Thermally Efficient, Space-Saving

Packages

10-Pin TDFN (3mm x 3mm x 0.8mm)

12-Bump UCSP (1.5mm x 2mm x 0.6mm)

♦ Pin-for-Pin Compatible with the MAX9700 and

MAX9712

MAX9705

2.3W, Ultra-Low-EMI, Filterless,

Class D Audio Amplifier

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-3405; Rev 3; 5/09

EVALUATION KIT

AVAILABLE

Cellular Phones

PDAs

MP3 Players

Portable Audio

PART

TEMP RANGE

PIN-

PACKAGE

TOP

MARK

MAX9705AETB+T

-40

C to +85

10 TDFN ACY

MAX9705AEBC+T

-40

C to +85

12 UCSP

ACH

MAX9705BETB+T

-40

C to +85

10 TDFN ACX

MAX9705BEBC+T

-40

C to +85

12 UCSP

ACG

Ordering Information continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

Selector Guide appears at end of data sheet.

30.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

FREQUENCY (MHz)

AMPLITUDE (dBμV/m)

FCC EMI LIMIT

MAXIM'S NEW ULTRA-LOW

OUTPUT SPECTRUM

EMI Spectrum Diagram

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.

Summary of content (18 pages)

PAGE 1
9-3405; Rev 3; 5/09 KIT ATION EVALU LE B A IL A AV 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier The MAX9705 3rd-generation, ultra-low EMI, mono, Class D audio power amplifier provides Class AB performance with Class D efficiency. The MAX9705 delivers 2.3W into a 4Ω load and offers efficiencies above 85%. Active emissions limiting (AEL) circuitry greatly reduces EMI by actively controlling the output FET gate transitions under all possible transient output-voltage conditions.
PAGE 2
MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 10-Pin TDFN (derate 24.4mW/°C above +70°C) .....1951.2mW 12-Bump UCSP (derate 6.1mW/°C above +70°C)........484mW Junction Temperature ......................................................+150°C Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .........
PAGE 3
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier (VDD = PVDD = V SHDN = 3.3V, VGND = VPGND = 0, SYNC = GND (FFM), RL = ∞, RL connected between OUT+ and OUT-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
Typical Operating Characteristics (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted. Typical Operating Characteristics for 4Ω load condition apply to the MAX9705_ETB+T only.) 0.1 0.01 1 0.1 0.2 0.4 0.6 0.8 1.0 1.2 0.5 1.0 1.5 0 2.0 0.4 0.6 0.8 OUTPUT POWER (W) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 0.01 1 0.
PAGE 5
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier VDD = 3.3V RL = 4Ω VDD = 5.0V RL = 4Ω VDD = 3.3V RL = 8Ω POUT = 450mW 10 POUT = 100mW 1 POUT = 800mW THD+N (%) 10 THD+N (%) POUT = 250mW 1 0.01 0.01 0.01 100 10k 1k 100k 10 100 10k 1k 10 100k 100 10k 1k FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. COMMON-MODE VOLTAGE EFFICIENCY vs. OUTPUT POWER EFFICIENCY vs. OUTPUT POWER 0.1 RL = 4Ω 50 40 80 30 0.5 1.0 1.5 2.0 2.
PAGE 6
Typical Operating Characteristics (continued) (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted. Typical Operating Characteristics for 4Ω load condition apply to the MAX9705_ETB+T only.) OUTPUT POWER vs. SUPPLY VOLTAGE 1.6 THD+N = 10% 1.0 THD+N = 1% 0.6 THD+N = 10% 2.0 1.5 3.0 THD+N = 1% 1.0 2.0 3.3V 1.5 1.0 0.4 0.5 fIN = 1kHz RL = 8Ω 0.2 0 fIN = 1kHz RL = 4Ω 0.5 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0 2.5 3.0 SUPPLY VOLTAGE (V) 3.5 4.0 4.5 5.0 5.
PAGE 7
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier WIDEBAND OUTPUT SPECTRUM SPREAD-SPECTRUM MODE WIDEBAND OUTPUT SPECTRUM FIXED-FREQUENCY MODE -60 -80 -40 -60 -80 -100 -100 RL = 8Ω VDD = 5.0V INPUTS AC GROUNDED -120 RL = 8Ω VDD = 5.0V INPUTS AC GROUNDED -120 -140 -140 100 10 0 1000 100 10 FREQUENCY (MHz) FREQUENCY (MHz) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 7.00 MAX9705 toc28 10 9 SUPPLY CURRENT (mA) SYNC = VDD (SSM) 8 7 6 SYNC = GND (FFM) 5 6.
PAGE 8
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 Functional Diagram 2.5V TO 5.5V 1µF 5 (B2) SHDN 1 (A1) 10 (B4) 6 (A3) VDD PVDD SYNC UVLO/POWER MANAGEMENT CLICK-AND-POP SUPPRESSION OSCILLATOR PVDD LOW-EMI DRIVER 1µF 2 (B1) IN+ 1µF 3 (C1) IN- 8 OUT+ (A4) PGND CLASS D MODULATOR PVDD OUT- 9 (C4) LOW-EMI DRIVER MAX9705 PGND PGND 7 (B3) GND 4 (C2) ( ) UCSP BUMP. FIGURE SHOWS MAX9705 CONFIGURED FOR SPREAD-SPECTRUM OPERATION.
PAGE 9
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier PIN BUMP TDFN UCSP NAME FUNCTION 1 A1 VDD Analog Power Supply 2 B1 IN+ Noninverting Audio Input Inverting Audio Input 3 C1 IN- 4 C2 GND Analog Ground 5 B2 SHDN Active-Low Shutdown Input. Connect to VDD for normal operation. A3 SYNC Frequency Select and External Clock Input. SYNC = GND: Fixed-frequency mode with fS = 1100kHz. SYNC = VDD: Spread-spectrum mode with fS = 1220kHz ±120kHz.
PAGE 10
MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier tSW VIN- VIN+ OUT- OUT+ tON(MIN) VOUT+ - VOUT- Figure 1. MAX9705 Outputs with an Input Signal Applied Table 1. Operating Modes SYNC INPUT MODE GND FFM with fS = 1100kHz VDD SSM with fS = 1220kHz ±120kHz Clocked FFM with fS = external clock frequency Spread-Spectrum Modulation (SSM) Mode The MAX9705 features a unique spread-spectrum mode that flattens the wideband spectral components, improving EMI emissions by 5dB.
PAGE 11
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier tSW tSW MAX9705 tSW tSW VIN- VIN+ OUT- OUT+ tON(MIN) VOUT+ - VOUT- Figure 2. MAX9705 Output with an Input Signal Applied (SSM Mode) Filterless Modulation/Common-Mode Idle The MAX9705 uses Maxim’s unique modulation scheme that eliminates the LC filter required by traditional Class D amplifiers, improving efficiency, reducing component count, and conserving board space and system cost.
PAGE 12
MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier EFFICIENCY vs. OUTPUT POWER VIN = 0V 100 MAX9705 90 EFFICIENCY (%) 80 OUT- 70 60 50 CLASS AB 40 30 OUT+ 20 VDD = 3.3V fIN = 1kHz RL = 8Ω 10 0 0 Figure 3. MAX9705 Outputs with No Input Signal Click-and-Pop Suppression The MAX9705 features comprehensive click-and-pop suppression that eliminates audible transients on startup and shutdown. While in shutdown, the H-bridge is in a high-impedance state.
PAGE 13
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier DC-Coupled Input The input amplifier can accept DC-coupled inputs that are biased within the amplifier’s common-mode range (see the Typical Operating Characteristics). DC coupling eliminates the input-coupling capacitors, reducing component count to potentially one external component (see the System Diagram). However, the low-frequency rejection of the capacitors is lost, allowing low-frequency signals to feed through to the load.
PAGE 14
MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier VDD 1µF VDD IN+ RIGHT-CHANNEL DIFFERENTIAL AUDIO INPUT PVDD MAX9705 IN- OUT+ OUTSYNC 1µF VDD IN+ LEFT-CHANNEL DIFFERENTIAL AUDIO INPUT IN- PVDD MAX9705 OUT+ OUTSYNC Figure 6. Master-Slave Stereo Configuration TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER VDD = 3.3V SLAVE DEVICE fIN = 1kHz SYNC = GND (FFM) RL = 8Ω VDD = 3.
PAGE 15
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 1µF CW 22kΩ 1µF IN- 50kΩ IN- CW 50kΩ MAX9705 1µF IN+ MAX9705 IN+ 22kΩ 1µF Figure 9a. Single-Ended Drive of MAX9705 Plus Volume Figure 9b. Improved Single-Ended Drive of MAX9705 Plus Volume Pin Configurations Selector Guide PART 6 10 TDFN 12 MAX9705BEBC+T 12 UCSP 12 MAX9705CETB+T 10 TDFN 15.6 MAX9705CEBC+T 12 UCSP 15.
PAGE 16
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 System Diagram VDD 1µF VDD 0.1µF AUX_IN OUT 2.2kΩ OUT BIAS VDD PVDD IN+ OUT+ MAX9705 IN- OUT- SHDN SYNC CODEC/ BASEBAND PROCESSOR 2.2kΩ MAX4063 0.1µF IN+ VDD IN0.
PAGE 17
2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier PROCESS: BiCMOS For the latest package outline information and land patterns, go to www.maxim-ic.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 DOCUMENT NO.
PAGE 18
MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier Revision History REVISION NUMBER REVISION DATE 2 8/08 Removed µMAX package option 3 5/09 Removed SYNC unconnected mode DESCRIPTION PAGES CHANGED 1–7, 9, 10, 15 3, 7, 9, 10, 14 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.