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SSM2804:  Audio Subsystem with Class-D Speaker and Capless Headphone Driver

Product Details

Product Status:Recommended for New Designs

The SSM2804 is an audio subsystem designed specifically for mobile phones and portable multimedia devices. This highly flexible subsystem includes three input channels that can be configured as single-ended stereo or monaural differential for multimedia audio sources.

Each set of inputs is independently adjustable with the 2-wire I2C interface and features an adjustable gain over a 30 dB range in steps of 1 dB. Each set of input channels also offers the choice of variable input impedance PGA mode or fixed input impedance boost mode. The input signals are then mixed and routed to the desired set of outputs. This configuration is set using the 2-wire I2C control interface.

The SSM2804 includes three selectable output modes.

The first output mode is a stereo Class-D speaker driver capable of delivering 2 × 1.4 W of continuous power to an 8 Ω bridge-tied load (BTL) with 1% THD + N when using a 5 V supply. This Class-D amplifier incorporates three-level Σ-Δ output modulation designed to increase battery life and improve EMI performance. The Class-D amplifier offers an I2C-adjustable volume control with a gain range from +12 dB to −63 dB in 31 steps.

The second output mode is a pair of high performance head-phone drivers capable of delivering 20 mW per channel into stereo 32 Ω single-ended loads with 1% THD + N. The stereo headphone drivers use a highly efficient, true ground centered Class-G architecture. The headphone outputs incorporate I2C-adjustable volume control with a gain range from 0 dB to −75 dB in 32 steps.

The third output mode is an integrated receiver path bypass switch for passing voice signals from the audio baseband.

The SSM2804 is specified over the industrial temperature range of −40°C to +85°C. It has built-in thermal shutdown and output short-circuit protection. The SSM2804 is available in a 30-ball, 2.5 mm × 3.0 mm wafer level chip scale package (WLCSP).


  • Mobile phones
  • Portable multimedia devices


  • 3 single-ended stereo audio inputs with optional differential mode
  • Stereo, 1.4 W, filterless Class-D amplifiers with Σ-Δ modulation
  • Integrated receiver path bypass switch
  • Configurable, high performance capless headphone output with true ground Class-G technology
  • Optional hardware-based headphone level limiter
  • I2C control interface
    - Volume control
    - Flexible input/output mixing
    - Output mode control
    - EMI emissions control
    - Automatic level control (ALC)
    - Adjustable headphone level limiter
  • Low shutdown current
  • Short-circuit and thermal protection
  • Pop-and-click suppression
  • Available in a 30-ball,
    2.5 mm × 3.0 mm WLCSP

Functional Block Diagram for SSM2804

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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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