Filterless, High Efficiency, Mono 2.5 W Class-D Audio Amplifier SSM2377 The SSM2377 operates with 92% efficiency at 1.4 W into 8 FEATURES from a 5.0 V supply and has an SNR of >100 dB. Filterless, Class-D amplifier with spread-spectrum - modulation Spread-spectrum pulse density modulation (PDM) is used to 2.5 W into 4 load and 1.4 W into 8 load at 5.0 V supply provide lower EMI-radiated emissions compared with other with <1% total harmonic distortion plus noise (THD + N) Class-D architectures. The inherent randomized nature of 92% efficiency at 5.0 V, 1.4 W into 8 speaker spread-spectrum PDM eliminates the clock intermodulation >100 dB signal-to-noise ratio (SNR) (beating effect) of several amplifiers in close proximity. High PSRR at 217 Hz: 80 dB The SSM2377 produces ultralow EMI emissions that signifi- Ultralow EMI emissions cantly reduce the radiated emissions at the Class-D outputs, Single-supply operation from 2.5 V to 5.5 V particularly above 100 MHz. The SSM2377 passes FCC Class B Gain select function: 6 dB or 12 dB radiated emission testing with 50 cm, unshielded speaker cable Fixed input impedance of 80 k without any external filtering. The ultralow EMI emissions of the 100 nA shutdown current SSM2377 are also helpful for antenna and RF sensitivity problems. Short-circuit and thermal protection with autorecovery The device is configured for either a 6 dB or a 12 dB gain setting Available in a 9-ball, 1.2 mm 1.2 mm WLCSP by connecting the GAIN pin to the VDD pin or the GND pin, Pop-and-click suppression respectively. Input impedance is a fixed value of 80 k, indepen- APPLICATIONS dent of the gain select operation. Mobile phones The SSM2377 has a micropower shutdown mode with a typical MP3 players shutdown current of 100 nA. Shutdown is enabled by applying Portable electronics SD a logic low to the pin. GENERAL DESCRIPTION The device also includes pop-and-click suppression circuitry, which minimizes voltage glitches at the output during turn-on The SSM2377 is a fully integrated, high efficiency, Class-D audio amplifier. It is designed to maximize performance for mobile and turn-off, reducing audible noise on activation and deactivation. phone applications. The application circuit requires a minimum Built-in input low-pass filtering is also included to suppress out- of external components and operates from a single 2.5 V to 5.5 V of-band noise interference to the PDM modulator. supply. It is capable of delivering 2.5 W of continuous output power The SSM2377 is specified over the industrial temperature range with <1% THD + N driving a 4 load from a 5.0 V supply. of 40 C to +85 C. It has built-in thermal shutdown and output The SSM2377 features a high efficiency, low noise modulation short-circuit protection. It is available in a halide-free, 9-ball, 0.4 mm scheme that requires no external LC output filters. The modu- pitch, 1.2 mm 1.2 mm wafer level chip scale package (WLCSP). lation operates with high efficiency even at low output power. FUNCTIONAL BLOCK DIAGRAM POWER SUPPLY 10F 2.5V TO 5.5V 0.1F VDD SSM2377 22nF 80k OUT+ AUDIO IN MODULATOR FET IN+ 80k OUT ( -) DRIVER AUDIO IN+ IN 22nF INTERNAL POP/CLICK BIAS SHUTDOWN OSCILLATOR AND EMI SD SUPPRESSION GND GAIN GAIN SELECT GAIN = 6dB OR 12dB Figure 1. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. 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Trademarks and registered trademarks are the property of their respective owners. 09824-001SSM2377 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation ...................................................................... 13 Applications ....................................................................................... 1 Overview ..................................................................................... 13 General Description ......................................................................... 1 Gain Selection ............................................................................. 13 Functional Block Diagram .............................................................. 1 Pop-and-Click Suppression ...................................................... 13 Revision History ............................................................................... 2 EMI Noise .................................................................................... 13 Specif icat ions ..................................................................................... 3 Output Modulation Description .............................................. 13 Absolute Maximum Ratings ............................................................ 5 Layout .......................................................................................... 14 Thermal Resistance ...................................................................... 5 Input Capacitor Selection .......................................................... 14 ESD Caution .................................................................................. 5 Power Supply Decoupling ......................................................... 14 Pin Configuration and Function Descriptions ............................. 6 Outline Dimensions ....................................................................... 15 Typical Performance Characteristics ............................................. 7 Ordering Guide .......................................................................... 15 Typical Application Circuits .......................................................... 12 REVISION HISTORY 5/11Revision 0: Initial Version Rev. 0 Page 2 of 16