Filterless, High Efficiency, Mono 3 W Class-D Audio Amplifier Data Sheet SSM2375 Spread-spectrum pulse density modulation (PDM) is used to FEATURES provide lower EMI-radiated emissions compared with other Filterless Class-D amplifier with spread-spectrum Class-D architectures. The inherent randomized nature of - modulation spread-spectrum PDM eliminates the clock intermodulation 3 W into 3 load and 1.4 W into 8 load at 5.0 V supply (beating effect) of several amplifiers in close proximity. with <1% total harmonic distortion (THD + N) 93% efficiency at 5.0 V, 1.4 W into 8 speaker The SSM2375 includes an optional modulation select pin >100 dB signal-to-noise ratio (SNR) (ultralow EMI emissions mode) that significantly reduces the High PSSR at 217 Hz: 80 dB radiated emissions at the Class-D outputs, particularly above Flexible gain adjustment pin: 0 dB to 12 dB in 3 dB steps 100 MHz. In ultralow EMI emissions mode, the SSM2375 Fixed input impedance: 80 k can pass FCC Class B radiated emission testing with 50 cm, User-selectable ultralow EMI emissions mode unshielded speaker cable without any external filtering. Single-supply operation from 2.5 V to 5.5 V The device also includes a highly flexible gain select pin that 20 nA shutdown current allows the user to select a gain of 0 dB, 3 dB, 6 dB, 9 dB, or Short-circuit and thermal protection with autorecovery 12 dB. The gain selection feature improves gain matching Available in 9-ball, 1.5 mm 1.5 mm WLCSP between multiple SSM2375 devices within a single application Pop-and-click suppression as compared to using external resistors to set the gain. APPLICATIONS The SSM2375 has a micropower shutdown mode with a typical Mobile phones shutdown current of 20 nA. Shutdown is enabled by applying MP3 players SD a logic low to the pin. Portable electronics The device also includes pop-and-click suppression circuitry. GENERAL DESCRIPTION This suppression circuitry minimizes voltage glitches at the The SSM2375 is a fully integrated, high efficiency, Class-D audio output during turn-on and turn-off, reducing audible noise amplifier. It is designed to maximize performance for mobile on activation and deactivation. phone applications. The application circuit requires a minimum Other features that simplify system-level integration of the of external components and operates from a single 2.5 V to 5.5 V SSM2375 include input low-pass filtering to suppress out-of-band supply. It is capable of delivering 3 W of continuous output power DAC noise interference to the PDM modulator and fixed-input with <1% THD + N driving a 3 load from a 5.0 V supply. impedance to simplify component selection across multiple The SSM2375 features a high efficiency, low noise modulation platform production builds. scheme that requires no external LC output filters. The modulation The SSM2375 is specified over the industrial temperature range continues to provide high efficiency even at low output power. of 40 C to +85 C. It has built-in thermal shutdown and output The SSM2375 operates with 93% efficiency at 1.4 W into 8 short-circuit protection. It is available in a halide-free, 9-ball, or with 85% efficiency at 3 W into 3 from a 5.0 V supply and 1.5 mm 1.5 mm wafer level chip scale package (WLCSP). has an SNR of >100 dB. FUNCTIONAL BLOCK DIAGRAM POWER SUPPLY 10F 2.5V TO 5.5V 0.1F VDD SSM2375 22nF OUT+ IN+ GAIN MODULATOR FET IN+ CONTROL OUT (-) DRIVER IN IN 22nF EDGE INTERNAL EDGE EMISSION BIAS SHUTDOWN OSCILLATOR CONTROL CONTROL SD GND GAIN R GAIN GAIN SELECT GAIN = 0dB, 3dB, 6dB, 9dB, OR 12dB Figure 1. Rev. A Document Feedback 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. No Tel: 781.329.4700 20102013 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com 09011-001SSM2375 Data Sheet 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 Specifications ..................................................................................... 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 4/13Rev. 0 to Rev. A Changes to Figure 33 and Figure 34 ............................................. 12 Changes to Gain Selection Section and Table 5 ......................... 13 Updated Outline Dimensions ....................................................... 15 9/10Revision 0: Initial Version Rev. A Page 2 of 16