The SSM2305 features a high efficiency, low noise modulation scheme that does not require external LC output filters. The modu-lation provides high efficiency even at low output power. The SSM2305 operates with 90% efficiency at 1.3 W into 8 Ω or 83% efficiency at 2.2 W into 4 Ω from a 5.0 V supply and has an SNR of >98 dB. Spread-spectrum pulse density modulation is used to provide lower EMI-radiated emissions compared with other Class-D architectures.
The SSM2305 has a micropower shutdown mode with a maximum shutdown current of 30 nA. Shutdown is enabled by applying a Logic 0 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, thus reducing audible noise on activation and deactivation.
The fully differential input of the SSM2305 provides excellent rejection of common-mode noise on the input. Input coupling capacitors can be omitted if the dc input common-mode voltage is approximately VDD/2.
The SSM2305 has excellent rejection of power supply noise, including noise caused by GSM transmission bursts and RF rectification. PSRR is typically 60 dB at 217 Hz.
The default gain of the SSM2305 is 18 dB, but users can reduce the gain by using a pair of external resistors.
The SSM2305 is specified over the commercial temperature range (−40°C to +85°C). It is available in both an 8-lead, 3 mm × 3 mm lead frame chip scale package (LFCSP) and an 8-lead mini small outline package (MSOP).
Applications
- Mobile phones
- MP3 players
- Portable gaming
- Portable electronics
- Educational toys
