LM4970 Datasheet, PDF (1/15 Pages) National Semiconductor (TI) – Audio Synchronized Color LED Driver

February 2005
LM4970
Audio Synchronized Color LED Driver
General Description
The LM4970 is a LED driver with an audio synchronization
mode that virtually eliminates the need for real time software
processing for LED lighting effects. The LM4970 includes
three individual PWM color LED drivers that provide up to
42mA of current drive for each PWM LED output.
The LM4970 features an audio synchronization mode where
the audio input signal that is mixed in from three audio inputs
is filtered into three frequency bands, with each frequency
band assigned to a specific PWM LED driver.
The PWM LED drivers can also be directly programmed
through an I²C compatible interface for applications where
user defined LED pattern, color, and intensity programmabil-
ity is a priority.
The LM4970 also features an audio input gain control which
allows the user to increase the gain if the audio input signal
does not create a bright enough effect on the LEDs. The
LM4970 is a feature rich LED driver that is available in a
space saving 14 pin non-pullback LLP package.
Key Specifications
j LED Drive Current per channel
V_DD = 5V
j Shutdown Current, V_DD = 5V
42mA (2X setting)
1.5µA (typ)
Features
n Audio synchronized color LED driver
n User defined LED pattern, color, and intensity capability
n Programmable:
LED Drive current
PWM frequency
High pass filter frequency select
Audio input signal gain
n Eliminates external LED current limiting resistors
n I²C compatible interface
n Ultra low shutdown current
Applications
n Cell Phones
n Portable MP3, CD, DVD, AAC players
n PDA’s
Block Diagram
FIGURE 1. Block Diagram
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