LM49150 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – Mono Class D Audio Subsystem with Earpiece Driver and Stereo Ground Referenced Headphone Amplifiers

LM49150
March 4, 2009
Mono Class D Audio Subsystem with Earpiece Driver and
Stereo Ground Referenced Headphone Amplifiers
General Description
The LM49150 is a fully integrated audio subsystem designed
for portable handheld applications such as cellular phones.
Part of National's Power Wise® product family, the LM49150
consumes very low power in the various modes of operation
and still providing great audio performance. The LM49150
combines a 1.25W mono E²S (Enhanced Emission Suppres-
sion) class D amplifier, 135mW Class AB earpiece amplifier,
42mW/channel stereo ground reference headphone ampli-
fiers, volume control, and mixing circuitry into a single device.
The filterless class D amplifier delivers 1.25W into an 8Ω load
with <1% THD+N with a 5V supply. The E²S class D amplifier
features a patented, ultra low EMI PWM architecture that sig-
nificantly reduces RF emissions while preserving audio qual-
ity. The 42mW/channel headphone drivers feature National’s
ground referenced architecture that creates a ground-refer-
enced output from a single supply, eliminating the need for
bulky and expensive DC-blocking capacitors, saving space
and minimizing cost.
The LM49150 features a fully differential mono input, and two
single-ended stereo inputs. The three inputs can be mixed/
multiplexed to either the speaker or headphone amplifiers.
Each input channel has an independent, 32-step digital vol-
ume control. The headphone output stage features an addi-
tional, 8-step gain control, while the speaker output stage has
a selectable 6dB or 12dB gain. The mixer, volume control and
device mode select are controlled through an I²C compatible
serial interface.
The LM49150’s superior click and pop suppression elimi-
nates audible transients on power-up/down and during shut-
down. The LM49150 is available in a ultra-small 20-bump
micro SMD package (2.225mm X 2.644mm).
Key Specifications
■ Output power at V_DD = 5V:
 Speaker:
  R_L = 8Ω BTL, THD+N ≤ 1%
 Headphone:
  R_L = 32Ω SE, THD+N ≤ 1%
 Earpiece:
  R_L = 8Ω SE, THD+N ≤ 1%
■ Output power at V_DD = 3.3V:
 Speaker:
  R_L = 8Ω BTL, THD+N ≤ 1%
 Headphone:
  R_L = 32Ω BTL, THD+N ≤ 1%
 Earpiece:
  R_L = 8Ω SE, THD+N ≤ 1%
■ Output Offset
LS Mode
HP Mode
Earpiece
■ Single Supply Operation (V_DD)
■ I²C Single Supply Operation
1.25W (typ)
42mW (typ)
135mW (typ)
520mW (typ)
42mW (typ)
35mW (typ)
9mV (typ)
1mV (typ)
1mV (typ)
2.7 to 5.5V
1.7 to 5.5V
Features
■ ^{E2S class D amplifier}
■ ^{Ground referenced headphone outputs — eliminates}
output coupling capacitors
■ ^{I2C volume and mode control}
■ ^{Mono earpiece amplifier}
■ ^{Flexible output for speaker and headphone output}
■ ^{20–bump micro SMD package}
■ ^{Soft enable function}
■ ^{“Click and Pop” suppression circuitry}
■ ^{Thermal shutdown protection}
■ ^{Low supply current}
■ ^{Micro-power shutdown}
Applications
■ ^{Mobile Phones}
■ ^PDAs
■ ^{Portable Electronics}
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www.national.com