LM49200 Datasheet, PDF (1/26 Pages) National Semiconductor (TI) – Stereo Class AB Audio Subsystem with a True Ground Headphone Amplifier

LM49200
May 21, 2009
Stereo Class AB Audio Subsystem with a True Ground
Headphone Amplifier
General Description
The LM49200 is a fully integrated audio subsystem with a
stereo power amplifier capable of delivering 500mW of con-
tinuous average power per channel into 8Ω with 1% THD+N
using a 3.3V supply. The LM49200 includes a separate stereo
headphone amplifier that can deliver 35mW per channel into
32Ω.
The LM49200 has three input channels. A pair of single-end-
ed inputs and a fully differential input channel. The LM49200
features a 32-step digital volume control on the input stage
and an 8-step digital volume control on the headphone output
stage.
The digital volume control and output modes are programmed
through a two-wire I²C compatible interface that allows flexi-
bility in routing and mixing audio channels.
The LM49200 is designed for cellular phone, PDA, and other
portable handheld applications. The high level of integration
minimizes external components. The True Ground head-
phone amplifier eliminates the physically large DC blocking
output capacitors reducing required board space and reduc-
ing cost.
Key Specifications
■ Supply Voltage (V_DD)
■ I²C Supply Voltage
■ Output power at V_DD = 5V,
  1% THD+N
R_L = 8Ω speaker
R_L = 32Ω headphone
■ Output power at V_DD = 3.3V,
  1% THD+N
2.7V ≤ V_DD ≤ 5.5V
1.7V ≤ I²CV_DD ≤ 5.5V
1.25W (typ)
38mW (typ)
R_L = 8Ω speaker
R_L = 32Ω headphone
■ PSRR:
  V_DD = 3.3V, 217Hz ripple, Mono In
■ Shutdown power supply current
520W (typ)
38mW (typ)
95dB (typ)
0.02μA (typ)
Features
■ ^{Differential mono input and stereo single-ended input}
■ ^{32-step digital volume control (-80 to +18dB)}
■ ^{Three independent volume channels (Left, Right, Mono)}
■ ^{Separate headphone volume control}
■ ^{Flexible output for speaker and headphone output}
■ ^{True Ground headphone amplifier eliminates large DC}
blocking capacitors reducing PCB space and cost
■ ^{Receiver pass-through capability}
■ ^{Soft enable function}
■ ^{RF immunity topology}
■ ^{“Click and Pop” suppression circuitry}
■ ^{Thermal shutdown protection}
■ ^{Micro-power shutdown}
■ ^{I2C control interface}
■ ^{Available in space-saving microSMD package}
Applications
■ ^{Portable electronic devices}
■ ^{Mobile Phones}
■ ^PDAs
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