What can you do with a chip that mixes three audio inputs, filters that audio into three frequency bands, and uses each frequency band to pulse-width modulate an output capable of driving up to 42 mA? Obviously, you can run the jukebox lighting effects on cellular telephones and personal audio players.
That's what National Semiconductor had in mind with its LM4970 audio-synchronized LED driver. This IC can pulse-modulate three outputs in response to the frequency content of three inputs. Absolutely no software or memory storage is necessary with the automatic mode. On the other hand, designers do have the option of using I2C for pattern control or for choosing automatic audio-synchronized pattern generation. Also, the I2C bus can be used for turning each driver on or off, adjusting LED brightness, and changing the high and mid-range frequency bands.
Available now in a 14-pin LLP, the LM4970 costs $0.90 in 1000-unit quantities.
See associated figure
National Semiconductor
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