The SSM2305RMZ-REEL is a fully integrated, high efficiency, Class-Daudio amplifier designed to maximize performance for mobilephone applications. The application circuit requires a minimumof external components and operates from a single 2.5 V to 5.5 Vsupply. It is capable of delivering 2.2 W of continuous outputpower with less than 1% THD + N driving a 4 Ω load from a5.0 V supply. It has built-in thermal shutdown and output short-circuitprotection.
The SSM2305RMZ-REEL features a high efficiency, low noise modulationscheme that does not require external LC output filters. The modulationprovides high efficiency even at low output power. TheSSM2305RMZ-REEL 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 toprovide lower EMI-radiated emissions compared with otherClass-D architectures.
The SSM2305RMZ-REEL has a micropower shutdown mode with a maximumshutdown current of 30 nA. Shutdown is enabled by applyinga Logic 0 to the SD pin. The device also includes pop-and-clicksuppression circuitry. This minimizes voltage glitches at theoutput during turn-on and turn-off, thus reducing audible noiseon activation and deactivation.
The fully differential input of the SSM2305RMZ-REEL provides excellentrejection of common-mode noise on the input. Input couplingcapacitors can be omitted if the dc input common-mode voltageis approximately VDD/2.
The SSM2305RMZ-REEL has excellent rejection of power supply noise,including noise caused by GSM transmission bursts and RFrectification. PSRR is typically 60 dB at 217 Hz.The default gain of the SSM2305RMZ-REEL is 18 dB, but users can reduce thegain by using a pair of external resistors.
The SSM2305RMZ-REEL is specified over the commercial temperature range(−40°C to +85°C). It is available in both an 8-lead, 3 mm × 3 mmlead frame chip scale package (LFCSP) and an 8-lead mini smalloutline package (MSOP).
Feature
- Filterless Class-D amplifier with Σ-Δ modulation
- No sync necessary when using multiple Class-D amplifiers from Analog Devices, Inc.
- 2.8 W into 4 Ω load and 1.6 W into 8 Ω load at 5.0 V supply with <10% total harmonic distortion (THD)
- 89% efficiency at 5.0 V, 1.3 W into 8 Ω speaker
- >98 dB signal-to-noise ratio (SNR)
- Single-supply operation from 2.5 V to 5.5 V
- 20 nA ultralow shutdown current
- Short-circuit and thermal protection
- Available in 8-lead, 3 mm × 3 mm LFCSP and MSOP
- Pop-and-click suppression
- Built-in resistors reduce board component count
- Fixed and user-adjustable gain configurations
Applications
- Mobile phones
- MP3 players
- Portable gaming
- Portable electronics
- Educational toys
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