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New Class-D Amplifier for High-Definition Automotive Audio from ST


The HFDA801A 4 x 80W Amplifier with high-performance DAC offers hi-fi quality sound under any load condition


The HFDA801A from STMicroelectronics is a high-resolution audio amplifier that is specifically designed for compact, cost-effective automotive applications.

Click for Larger Image - New Class-D Amplifier for High-Definition Automotive Audio from ST The HFDA801A is a 2MHz switching pulse-width modulation (PWM) Class-D amplifier with a quad-bridge configuration. An integrated high-performance digital-to-analog converter (DAC) ensures hi-fi quality sound under any load condition, with noiseless turn-on/turn-off and without creating any output artifacts. With a signal-to-noise ratio of 121dB, 120dB dynamic range, and only 10µV output noise, the HFDA801A delivers an extraordinary level of audio performance from an inexpensive small form-factor component.

The feedback configuration with integrated L-C low-pass filter provides an ultra-wide flat frequency response up to 80kHz and minimizes dependence on external components. The wide bandwidth allows use in high-definition (HD) audio applications, letting designers rely on excellent linearity and low distortion that are independent of the inductor and capacitor quality.

The specific architecture implemented derives all required voltages internally, enabling the HFDA801A to draw its supply from the vehicle battery without the need for additional power converters. The amplifier benefits from a wide range of load capabilities, ensuring stable performance even while driving high power on low-impedance loads of 2Ω on all four channels.

In addition, by integrating in-play diagnostics as well as a digital impedance meter and real-time load-current monitor, the HFDA801A can be used in safety-related audio applications that must demonstrate ASIL compliance, such as Acoustic Vehicle Alerting Systems (AVAS).

Features of the HFDA801A 4x80W Digital Input Class-D Audio Amplifier include

  • Integrated 120 dB D/A conversion
  • I²S and TDM digital input (up to 16 CH TDM)
  • Selectable input sample rate frequency (44.1/48/96/192 kHz)
  • Wide supply operating range: 4.5 V - 2518 V
  • PWM 2 MHz switching PWM:
    • Reduced size and cost of output LC
  • High Resolution Bandwidth support:
    • Up to 40 kHz (I²S 96 kHz) with attenuation [0 dB, -2 dB]
    • Up to 80 kHz (I²S 192 kHz) with attenuation [0 dB, -2 dB]
  • 4 x I²C addresses
  • 4Ω, 2Ω, 1Ω driving with output channels parallelization
  • MOSFET power outputs allowing high output power capability:
    • Typ 4 x 30 W /4 Ω @ 14.4 V, 1 kHz THD = 10%
    • Typ 4 x 25 W /4 Ω @ 14.4 V, 1 kHz THD = 1%
    • Typ 4 x 50 W /2 Ω @ 14.4 V, 1 kHz THD = 10%
    • Typ 4 x 80 W /4 Ω @ 25V V, 1 kHz THD = 10%
  • I²C full configurability and diagnostic:
    • 4 x Thermal warning and average junction temperature measurement on I²C (8 bits)
    • AC and DC diagnostic (independent of channel)
    • OCP protection scheme configurable (4 x OCP limit selectable)
    • Mute time configuration
    • DIM (digital impedance meter)
    • Feedback after filter configuration
  • Capability to run complete diagnostic in play:
    • Short to GND/VCC
    • DC offset detector
  • Extremely Low noise:
    • 13 µV A-weighted; 20 kHz (high gain) typ
  • Very low THD:
    • 0.02% at 1 W 1 kHz on 4 and 2 Ω loads typ
    • 0.08% 20-20 kHz (full audio band) on 4 and 2 Ω loads (1 W)
  • CD/Diag pin (3 selectable CD thresholds)
  • Synchronization output pin
  • Channel independent Mute/Play/Gain selection/Diagnostic
  • Real Time current monitor
  • Open Load in play
  • Battery load dump compatible (40 V)
  • Immune to pop/tick noise at turn on /off, battery variations (inside the operative range), during diagnostic
  • EMI compliance evaluated according to CISPR25
  • Legacy (no I²C mode)
  • Integrated short circuit protections
  • ESD integrated protections (2 kV HBM, 500 V / 750 V corner CDM)

More information on the HFDA801A 4x80W Class-D Audio Amplifier is available on the ST Web site at HFDA801A 4x80W Class-D Audio Amplifier product page.


The company's Web site address is www.st.com.
[Reprinted with kind permission from STMicroelectronics - Release Date, 2nd March, 2021]