ADI SSM2377ACBZ-R7

The SSM2377 is a highly integrated, high-efficiency Class-D audio amplifier designed for maximum performance in mobile phone applications. The application circuit requires minimal external components and operates from a single supply of 2.5 V to 5.5 V. With a 5.0 V supply, it delivers 2.5 W of continuous output power into a 4 Ω load with THD+N less than 1%.

The SSM2377 employs a high-efficiency, low-noise modulation scheme that eliminates the need for external LC output filters. This modulation scheme maintains high efficiency even at low output power levels.

With a 5.0 V supply, the SSM2377 drives 1.4 W into an 8 Ω load at 92% efficiency with SNR greater than 100 dB.

Compared to other Class-D architectures, spread-spectrum PDM provides lower EMI emissions. The inherently random nature of spread-spectrum PDM prevents clock intermodulation (beat frequency effects) among multiple closely spaced amplifiers.

The SSM2377 produces extremely low EMI emissions, significantly reducing radiated emissions from the Class-D output, particularly above 100 MHz. The SSM2377 passes FCC Class B radiated emissions testing using a 50 cm unshielded speaker cable with no external filtering. The ultra-low EMI characteristics also help address antenna and RF sensitivity issues.

The device can be configured for 6 dB or 12 dB gain by connecting the GAIN pin to the VDD pin or GND pin. The input impedance is a fixed 80 kΩ, independent of gain selection.

The SSM2377 features a micropower shutdown mode with a typical shutdown current of 100 nA. Applying a logic low to the SD pin enables shutdown mode.

The device also incorporates pop and click suppression circuitry to minimize output voltage transients during power-up and power-down, reducing audible noise during startup and shutdown. An integrated input low-pass filter suppresses out-of-band noise interference to the PDM modulator.

The SSM2377 is rated for the -40°C to +85°C industrial temperature range. It features integrated thermal shutdown and output short-circuit protection, housed in a 9-ball, 0.4 mm pitch, 1.2 mm × 1.2 mm halogen-free WLCSP.

• Filterless, Class-D amplifier with Σ-Δ modulation spread-spectrum technology; delivers 2.5 W into 4 Ω and 1.4 W into 8 Ω loads from a 5.0 V supply with THD+N < 1%
• Efficiency: 92% (5.0 V, 1.4 W into 8 Ω speaker)
• SNR: >100 dB
• High PSRR (at 217 Hz): 80 dB
• Ultra-low EMI emissions
• Single supply: 2.5 V to 5.5 V
• Selectable gain: 6 dB or 12 dB
• Fixed input impedance: 80 kΩ
• Shutdown current: 100 nA
• Short-circuit and thermal protection with auto-recovery
• Available in 9-pin 1.2 mm x 1.2 mm WLCSP package
• Pop and click suppression

• Mobile phones
• MP3 players
• Portable electronic devices