ADI SSM4567ACBZ-R7

The SSM4567 is a digital input Class D power amplifier with an integrated boost converter that delivers higher output power than a standard battery supply. This means the maximum output power remains constant across the battery voltage range. The SSM4567 is ideal for power-sensitive applications where system noise can corrupt small analog signals transmitted to the amplifier, such as mobile phones, tablets, and portable multimedia players.

The SSM4567 integrates an audio DAC, a power amplifier, and a PDM or PCM (I²S/TDM) digital audio interface on a single chip. With the SSM4567, audio can be transmitted digitally to the audio amplifier, significantly reducing the impact of noise sources on the transmitted audio without requiring input coupling capacitors. Powered by a 3.6 V supply, the SSM4567 delivers 2.5 W continuous output power into a 4 Ω load with THD+N less than 1%.

The SSM4567 can be controlled via I2C, PDM mode code control, or TDM control. It can also operate in standalone mode without a control interface.

The SSM4567 features built-in sense circuitry for output current, output voltage, and VBAT supply voltage monitoring. Current sensing is achieved using an on-chip sense resistor connected between the output pin and the load. Output current and voltage are fed to ADCs, whose outputs are available through a digital serial output port. The VBAT supply voltage can be used in conjunction with a fully configurable AGC circuit. The AGC limits the maximum output at low battery voltages to prevent excessive current draw from the battery, thereby extending battery life.

The SSM4567 employs a high-efficiency, low-noise modulation scheme that eliminates the need for an external LC output filter. The closed-loop five-level modulator design preserves the advantages of a purely digital amplifier while delivering excellent PSRR and audio performance. This modulation maintains high efficiency at low power consumption with an SNR of 104 dB (A-weighted). Spread-spectrum pulse density modulation provides lower EMI compared to other Class D architectures.

The SSM4567 features an ultralow-power shutdown mode with a typical shutdown current of 0.2 μA from the VBAT supply. Shutdown is triggered automatically by gating the input clock and data signals.

The SSM4567 is rated for the -40°C to +85°C industrial temperature range. It includes thermal shutdown and short-circuit protection for both the amplifier and boost outputs, and is housed in a 19-ball, 1.74 mm × 2.1 mm WLCSP.

• Filterless Class-D amplifier with spread-spectrum Σ-Δ modulation, integrated boost regulator (5.1 V)
• Digital readback of output voltage, output current, and VBAT supply voltage
• Integrated boost regulator
• Multiple serial data formats: PDM input/output; TDM slave supporting up to 8 devices on a single bus; I2S or left-justified slave supporting up to 4 devices on a single I2S bus for multi-chip configurations
• 8 kHz to 192 kHz PCM sample rate
• 2.048 to 6.14 MHz PDM input sample rate
• Configuration via I2C control, TDM control, or PDM mode codes
• Standalone control mode
• Drives 4 Ω load at 2.5 W and 8 Ω load at 1.42 W from 3.6 V supply, THD+N < 7%
• 19-ball, 1.74 mm × 2.1 mm, 0.4 mm pitch WLCSP package
• System efficiency: 89.7% (1 W output, VBAT = 3.6 V)
• Output noise: 21.7 μV rms (A-weighted)
• THD+N: 0.025% (1 kHz, 500 mW output power)
• PSRR: 90 dB (217 Hz, injected input)
• Output current sense SNR: 72 dB; voltage sense SNR: 77 dB
• Quiescent power consumption: 19.8 mW
• Pop and click suppression
• Flexible battery-tracking AGC
• Short-circuit protection on boost and Class-D output, plus thermal protection with auto-recovery
• Smart shutdown upon PDM stop condition or missing clock detection
• DC-blocking HPF and static input DC protection on PDM input
• Selectable ultra-low EMI and low-latency modes

• Mobile phones
• Tablets
• Portable media players