LM4946_07 Datasheet, PDF (1/34 Pages) National Semiconductor (TI) – Output Capacitor-Less Audio Subsystem with Programmable National 3D

June 2007
LM4946
Output Capacitor-Less Audio Subsystem with
Programmable National 3D
General Description
The LM4946 is an audio power amplifier capable of delivering
540mW of continuous average power into a mono 8Ω
bridged-tied load (BTL) with 1% THD+N, 35mW per channel
of continuous average power into stereo 32Ω single-ended
(SE) loads with 1% THD+N, or an output capacitor-less (OCL)
configuration with identical specifications as the SE configu-
ration, from a 3.3V power supply.
The LM4946 has three input channels: one pair for a two-
channel stereo signal and the third for a differential single-
channel mono input. The LM4946 features a 32-step digital
volume control and eight distinct output modes. The digital
volume control, 3D enhancement, and output modes (mono/
SE/OCL) are programmed through a two-wire I²C or a three-
wire SPI compatible interface that allows flexibility in routing
and mixing audio channels.
The LM4946 is designed for cellular phone, PDA, and other
portable handheld applications. It delivers high quality output
power from a surface-mount package and requires only sev-
en external components in the OCL mode (two additional
components in SE mode).
Key Specifications
■ THD+N at 1kHz, 540mW
 into 8Ω BTL (3.3V)
■ THD+N at 1kHz, 35mW
 into 32Ω SE (3.3V)
■ Single Supply Operation (V_DD)
■ I²C/SPI Single Supply Operation
  LLP
  micro SMD
1.0% (typ)
1.0% (typ)
2.7 to 5.5V
2.2 to 5.5V
1.7 to 5.5V
Features
■ ^{I2C/SPI Control Interface}
■ ^{I2C/SPI programmable National 3D Audio}
■ ^{I2C/SPI controlled 32 step digital volume control (-54dB to}
+18dB)
■ ^{Three independent volume channels (Left, Right, Mono)}
■ ^{Eight distinct output modes}
■ ^{LLP and microSMD surface mount packaging}
■ ^{“Click and Pop” suppression circuitry}
■ ^{Thermal shutdown protection}
■ ^{Low shutdown current (0.02uA, typ)}
■ ^{RF immunity topology}
Applications
■ ^{Mobile Phones}
■ ^PDAs
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