Filterless High Efficiency Mono 3 W Class-D Audio Amplifier
The SSM2317 features a high efficiency, low noise modulation scheme that does not require any external LC output filters. The modulation continues to provide high efficiency even at low output power. It operates with 93% efficiency at 1.4 W into 8 Ω or 85% efficiency at 3 W into 3 Ω from a 5.0 V supply and has an SNR of >93 dB. Spread-spectrum pulse density modulation is used to provide lower EMI radiated emissions compared with other Class-D architectures.
Automatic level control (ALC) can be activated to suppress clipping and improve dynamic range. This feature only requires one external resistor tied to GND via the VTH pin and an activation voltage on the ALC_EN pin. The SSM2317 has a micropower shutdown mode with a typical shutdown current of 20 nA. Shutdown is enabled by applying a logic low to the SD pin. The device also includes pop-and-click suppression circuitry. This minimizes voltage glitches at the output during turn-on and turn-off, reducing audible noise on activation and deactivation.
The default gain of the SSM2317 is 18 dB, but users can reduce the gain by using a pair of external resistors (see the Gain section). The SSM2317 is specified over the commercial temperature range of −40°C to +85°C. It has built-in thermal shutdown and output short-circuit protection. It is available in a 9-ball, 1.5 mm × 1.5 mm wafer level chip scale package (WLCSP).
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