Semiconductor Corp.'s stereo analog
with integrated Class G headphone amplifier and automatic level control (ALC)
is for smartphones and feature phones. The PowerWise LM49251's Class G
headphone amp reduces the supply voltage to lower power consumption and extend
audio (MP3, movies, etc.) playback time. The loudspeaker's ALC provides
designers with options to control audio distortion levels and prevent speaker
National's LM49251stereo analog subsystem combines a 1.4W Class
D speaker amplifier, 20 mW Class G headphone amplifier and ALC in a 2.55 by
3.02 mm package. The LM49251 offers low power consumption, consuming less than
7 mA of quiescent current at 3.3V for the loudspeaker and headphone. The
LM49251's ALC feature provides designers with a programmable output power
limiter for speaker protection and clip level select.
Offered in a 30-bump micro SMD package, the LM49251 provides enhanced Emission Suppression
(E2S) and a Class D amplifier featuring a patented, ultra-low EMI pulse-width
modulation (PWM) architecture that significantly reduces RF emissions while
preserving audio quality. The LM49251's Class G headphone architecture
significantly increases audio playback time with its adaptive power supply
approach, enabling low supply rails.
no-clip ALC feature prevents distortion as battery voltages drop, allowing
small signals to be amplified at high gains while preventing clipping of
high-level signals. Its multiple inputs provide configurability for addressing
different system requirements, and the LM49251's mode selection, shutdown and
volume are controlled through an I2C compatible interface. The IC's
click-and-pop suppression eliminates audible transients on power up and during
introduced the LM49153 mono audio subsystem,
which includes the same features as the LM49251, while integrating noise gate
functionality onto the Class D amplifier. The noise gate feature prevents noise
from being amplified when the volume is turned up. The LM49153 is offered in a
25-bump, 2.30 by 2.42 mm, micro SMD package.
During a teardown of the iPad Air and Microsoft Surface Pro 3 at the Medical Design & Manufacturing Show in Schaumburg, Ill., an engineer showed this "inflammatory" video about the dangers of maliciously mishandling lithium-ion batteries.
The Window Watcher stops the burglar before he does damage or enters the house. House alarm service companies set off alarms and call the service only after the burglar has damaged and entered the house.
If you’re designing a handheld device or industrial machine that will employ a user interface, then you’ll want to check out the upcoming Design News Continuing Education Center course, "Engineering Principles Behind Advanced User Interface Technologies.”
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.