LM49101 Datasheet, PDF (1/30 Pages) National Semiconductor (TI) – Mono Class AB Audio Subsystem with a True Ground Headphone Amplifier and Earpiece Switch

LM49101
March 23, 2009
Mono Class AB Audio Subsystem with a True Ground
Headphone Amplifier and Earpiece Switch
General Description
The LM49101 is a fully integrated audio subsystem with a
mono power amplifier capable of delivering 540mW of con-
tinuous average power into an 8Ω BTL speaker load with 1%
THD+N using a 3.3V supply. The LM49101 includes a sepa-
rate stereo headphone amplifier that can deliver 44mW per
channel into 32Ω loads using a 2.75V supply.
The LM49101 has four input channels. A pair of single-ended
inputs and a fully differential input channel with volume control
and amplification stages. Additionally, a bypass differential
input is available that connects directly to the mono speaker
outputs through an analog switch without any amplification or
volume control stages. The LM49101 features a 32–step dig-
ital 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, programmed
through a two-wire I²C compatible interface, allows flexibility
in routing and mixing audio channels.
The LM49101 is designed for cellular phones, PDAs, and
other portable handheld applications. The high level of inte-
gration minimizes external components. The True Ground
headphone amplifier eliminates the physically large DC block-
ing output capacitors reducing required board space and
reducing cost.
Key Specifications
■ Supply Voltage (V_DDLS)
■ Supply Voltage (V_DDHP)
■ I²C Supply Voltage
■ Output power
  V_DDLS = 5V, V_DDHP = 2.75V
   1% THD+N
R_L = 8Ω speaker
R_L = 32Ω headphone
2.7V ≤ V_DDLS ≤ 5.5V
1.8V ≤ V_DDHP ≤ 2.9V
1.7V ≤ I²CV_DD ≤ 5.5V
1.3W (typ)
45mW (typ)
■ Output Power
  V_DDLS = 3.3V, V_DDHP = 2.75V
  1% THD+N
R_L = 8Ω speaker
R_L = 32Ω headphone
■ PSRR:
  V_DD = 3.3V, 217Hz ripple, Mono In
■ Shutdown power supply current
540W (typ)
40mW (typ)
90dB (typ)
0.01μA (typ)
Features
■ ^{Differential mono input and stereo single-ended input}
■ ^{Separate earpiece (receiver) differential input}
■ ^{Analog switch for a separate earpiece path}
■ ^{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.
■ ^{Hardware reset 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
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2009 National Semiconductor Corporation 300862
www.national.com