LM4845 Datasheet, PDF (1/29 Pages) National Semiconductor (TI) – Output Capacitor-less Audio Subsystem with Programmable National 3D

March 2005
LM4845
Output Capacitor-less Audio Subsystem with
Programmable National 3D
General Description
The LM4845 is an audio power amplifier capable of deliver-
ing 500mW of continuous average power into a mono 8Ω
bridged-tied load (BTL) with 1% THD+N, 25mW 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 specification as the SE
configuration, from a 3.3V power supply.
The LM4845 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 pro-
grammed through a two-wire I²C or a three-wire SPI com-
patible interface that allows flexibility in routing and mixing
audio channels. The LM4845 has three input channels: one
pair for a two-channel stereo signal and the third for a
single-channel mono input.
The LM4845 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
seven external components in the OCL mode (two additional
components in SE mode).
Key Specifications
j THD+N at 1kHz, 500mW
into 8Ω BTL (3.3V)
j THD+N at 1kHz, 25mW
into 32Ω SE (3.3V)
j Single Supply Operation (V_DD)
j I²C/SPI Single Supply Operation
1.0% (typ)
1.0% (typ)
2.7 to 5.5V
2.2 to 5.5V
Features
n I²C/SPI Control Interface
n I²C/SPI programmable National 3D Audio
n I²C/SPI controlled 32 step digital volume control (-54dB
to +18dB)
n Three independent volume channels (Left, Right, Mono)
n Eight distinct output modes
n microSMD surface mount packaging
n “Click and Pop” suppression circuitry
n Thermal shutdown protection
n Low shutdown current (0.1uA, typ)
Applications
n Moblie Phones
n PDAs
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© 2005 National Semiconductor Corporation DS201059
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