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 I2 C 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 I2 C 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 Ohms bridge-tied load (BTL) with 1% THD + N when using a 5 V supply. This Class-D amplifier incorporates three-level sigma-delta output modulation designed to increase battery life and improve EMI performance. The Class-D amplifier offers an I2 C-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 headphone drivers capable of delivering 20 mW per channel into stereo 32W 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 I 2 C-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).