ALLGEMEINE BESCHREIBUNG

The SSM3302 is a fully integrated, high efficiency, stereo Class-D audio amplifier. The application circuit requires minimal external components and operates from a single 7 V to 18 V supply. The device is capable of delivering 2 × 10 W of continuous output power into a 4 Ω load (or 2 × 8 W into 8 Ω) with <1% THD + N from a 12 V supply. In addition, while mono mode is activated, the user can drive a load as small as 2 Ω up to 20 W continuous output power by stacking the stereo output terminals.

The SSM3302 features a high efficiency, low noise modulation scheme that requires no external LC output filters. This scheme continues to provide high efficiency even at low output power.  The SSM3302 operates with 90% efficiency at 7 W into an 8 Ωload or with 82% efficiency at 10 W into 4 Ω from a 12 V supply, and it has an SNR of >98 dB.

Spread spectrum pulse density modulation (PDM) is used to provide lower EMI radiated emissions compared with other Class-D architectures. The SSM3302 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 SSM3302 can pass FCC Class-B emissions testing with an unshielded 20 inch cable using common-mode choke-based filtering.

The fully differential input of the SSM3302 provides excellent rejection of common-mode noise on the input. The device also includes a highly flexible gain select pin that only requires one series resistor to choose a gain between 9 dB and 24 dB, with no change to the input impedance. The benefit of this is to improve gain matching between multiple SSM3302 devices within a single application compared with using external resistors to set gain.

The SSM3302 includes an integrated voltage regulator that generates a 5 V rail.

The SSM3302 has a micropower shutdown mode with a typical shutdown current of 10 µA. Shutdown is enabled by applying a logic low to the SD pin. 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 during activation and deactivation.

Other included features to simplify system level integration of the SSM3302 are input low-pass filtering to suppress out-of band DAC noise interference to the pulse density modulator, fixed input impedance to simplify component selection across multiple platform production builds,and a thermal warning indicator pin.

The SSM3302 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 halide-free, 40-lead, 6 mm × 6 mm lead frame chip scale package (LFCSP).

 

FEATURES

Filterless stereo Class-D amplifier with Σ-Δ modulation

2 × 10 W into 4 Ω load and 2 × 8 W into 8 Ω load at 12 V supply with <1% total harmonic distortion plus noise (THD + N)

91% efficiency at 12 V, 8 W into 8 Ω speaker

98 dB signal-to-noise ratio (SNR)

Single-supply operation from 7 V to 18 V

Flexible gain adjustment pin from 9 dB to 24 dB

Fixed input impedance of 40 kΩ

Mono output mode pin for 1 × 20 W output power into 2 Ω

10 µA shutdown current

Short-circuit and thermal protection

Available in a 40-lead, 6 mm × 6 mm LFCSP

Pop-and-click suppression

User-selectable ultralow EMI emissions mode

Thermal warning indicator

Power-on reset

 

ANWENDUNGEN

Mobile computing

Flat panel televisions

Media docking stations

Portable electronics

Sound bars

 

ANWENDUNGSINFORMATIONEN

OVERVIEW

The SSM3302 stereo Class-D audio amplifier features a filterless modulation scheme that greatly reduces the external component count, conserving board space and reducing system cost. The SSM3302 does not require an output filter; it relies on the inherent inductance of the speaker coil and the natural filtering of the speaker and human ear to recover the audio component of the square wave output.