LP3950 Datasheet, PDF (1/31 Pages) National Semiconductor (TI) – Color LED Driver with Audio Synchronizer

February 2005
LP3950
Color LED Driver with Audio Synchronizer
General Description
The LP3950 is a color LED driver with a built-in audio
synchronization feature for any analog audio input such as
polyphonic ring tones and MP3 music. LEDs can be syn-
chronized to an audio signal with two methods - amplitude
and frequency. Also several fine tuning options are available
for differentiation purposes. The chip also has an unique
AGC (Automatic Gain Control) feature which tracks the input
signal level and automatically adjusts the gain to an optimal
value.
The LP3950 has a high efficiency magnetic DC/DC con-
verter with programmable output voltage and switching fre-
quency. The converter has high output current capability so it
is also able to drive flash LEDs in camera phone applica-
tions.
The LP3950 is similar to LP3933 and LP3936 in that the
color LEDs (or RGB LEDs) can also be programmed to
generate light patterns (programmable color, intensity, on/off
timing, slope and blinking cycle).
All functions are software controllable through a SPI or I²C
compatible interface but the device also supports one pin
control for enabling predefined (default) audio synchroniza-
tion mode.
Features
n Audio synchronization for color LEDs with two modes:
Amplitude and Frequency
n Programmable frequency and amplitude response with
tracking speed control
n Automatic gain control or selectable gain for input signal
optimization
n RGB pattern generator similar to LP3933/LP3936
n Magnetic DC-DC boost converter with programmable
boost output voltage
n Selectable SPI or I²C compatible interface
n One pin default enable for non-serial interface users.
One pin selector for synchronization mode
n Space efficient 32-pin thin CSP laminate package
Applications
n Cellular phones
n MP3/CD/minidisc players
n Toys
Typical Application
© 2005 National Semiconductor Corporation DS201293
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