TAS2557

• Ultra low-noise mono boosted class-D amplifier
  • 5.7 W at 1% THD+N and 6.9 W at 10% THD+N into 4-Ω load from 4.2-V supply
  • 3.8 W at 1% THD+N and 4.5 W at 10% THD+N into 8-Ω load from 4.2-V supply
• Output noise for DAC + class-D (ICN) is 15.9 µV
• DAC + class-D SNR 111 dB at 1%THD+N/8 Ω
• THD+N –90 dB at 1 W / 8 Ω with flat frequency response
• Post-filter feedback (PFFB)
• PSRR 110 dB for 200 mV_pp ripple at 217 Hz
• Input sample rates from 8 kHz to 96 kHz
• Built-in speaker sense
  • Measures speaker current and voltage
  • Measures VBAT voltage, chip temperature
• Dedicated real-time dual-core DSP for speaker protection
  • Thermal and excursion protection
  • Detects speaker leaks and damage
• High efficiency class-H boost converter with multi-level tracking
  • 86% at 500 mW in 8 Ω with 3.6 V V_BAT
  • 87% at 700 mW in 8 Ω with 4.2 V V_BAT
• Configurable automatic gain control (AGC)
  • Limits battery current consumption
• Adjustable class-D switching edge-rate control
• Thermal, short-circuit, and under-voltage protection
• I²S, Left-justified, right-justified, DSP, and TDM input and output interface,
• I²C or SPI interface for register control
• Stereo configuration using two TAS2557 devices
• Power supplies
  • Boost input: 2.9 V to 5.5 V
  • Analog/digital: 1.65 V to 1.95 V
  • Digital I/O: 1.62 V to 3.6 V
• 42-ball, 0.5-mm pitch, DSBGA package

The TAS2557 device is a state-of-the-art Class-D audio amplifier which is a full system on a Chip (SoC). The device features a ultra low-noise audio DAC and Class-D power amplifier which incorporates speaker voltage and current sensing feedback. An on-chip, low-latency DSP supports Texas Instruments SmartAmp speaker protection algorithms to maximizes loudness while maintaining safe speaker conditions.

The device can be used easily with any processor with an I2S output and stereo implementations are possible when using two TAS2557 devices. Separate tuning for different speakers is supported allowing customers to add value while maintaining form factor designs. Additionally, the TAS2557 supports separate voice and audio tuning dynamically with ultra-low 15.9 µV ICN regardless of mode of operation making receiver/speaker implementations possible.

A Class-H boost converter generates the Class-D amplifier supply rail. When the audio signal only requires a lower Class-D output power, the boost improves system efficiency by deactivating and connecting V_BAT directly to the Class-D amplifier supply. When higher audio output power is required, the multi-level boost quickly activates tracking the signal to provide the additional voltage to the load.