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ADI SSM2356: 2 × 2W Filterless Class-D Stereo Audio Amplifier


What is it?
The SSM2356 is a fully integrated, high efficiency, stereo Class-D audio amplifier. It is designed to maximize performance for mobile phone applications. The application circuit requires a minimum of external components and operates from a single 2.5 V to 5.5 V supply. It is capable of delivering 2 × 2W of contin-uous output power with <1% THD + N driving a 4 Ω load from a 5.0 V supply. The SSM2356 features a high efficiency, low noise modulation scheme that requires no external LC output filters. The modulation continues to provide high efficiency even at low output power. It operates with 92% efficiency at 1.4 W into 8 Ω or 85% efficiency at 2.0 W into 4 Ω from a 5.0 V supply and has an SNR of >103 dB. Spread-spectrum pulse density modulation is used to provide lower EMI-radiated emissions compared with other Class-D architectures. The SSM2356 includes an optional modulation select pin (ultralow EMI emission mode) that significantly reduces the radiated emissions at the Class-D outputs, particularly above 100 MHz. The SSM2356 has a micropower shutdown mode with a typical shutdown current of 20 nA. Shutdown is enabled by applying a logic low to the SDNR and SDNL pins. The device also includes pop-and-click suppression circuitry that minimizes voltage glitches at the output during turn-on and turn-off, reducing audible noise on activation and deactivation. The fully differential input of the SSM2356 provides excellent rejection of common-mode noise on the input. Input coupling capacitors can be omitted if the dc input common-mode voltage is approximately VDD/2. The preset gain of SSM2356 can be selected between 6 dB and 18 dB with no external components and no change to the input impedance. Gain can be further reduced to a user-defined setting by inserting series external resistors at the inputs. The SSM2356 is specified over the commercial temperature range (−40°C to +85°C). It has built-in thermal shutdown and output short-circuit protection. It is available in a 16-ball, 1.66 mm × 1.66 mm wafer level chip scale package (WLCSP).

How is it used?
Handset and other handheld devices

What are the key features and customer benefits?
* Emission control pin for extra low EMI option
* Smallest Stereo classD amp 1.6mmx1.6mm
* 2x 2W into 4 Ω load and 1.4 W into 8 Ω load at 5.0 V supply with <1% total
* harmonic distortion (THD + N)
* 90% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
* >103 dB signal-to-noise ratio (SNR)
* Single-supply operation from 2.5 V to 5.5 V
* 20 nA ultralow shutdown current
* Short-circuit and thermal protection
* Pop-and-click suppression
* Built-in resistors reduce board component count

End Market:
Comms - Broadband; Comms - Other; Consumer - Audio;
Comms - WireLess; Comp - Peripherals; Comp - Mobile; Comp - Other