AS3668_07 Datasheet, PDF (27/59 Pages) ams AG – 4 Channel Breathlight Controller

AS3668
Data Sheet - Detailed Description
Figure 36. Startup and operating mode selection
8.7.1 GPIO/AUDIO_IN Automatic Pattern Start-up Mode
As described in the previous chapter it is basically possible to start up the device using the I²C clock line. In some cases it is not possible to
configure AS3668 in an application because the application processor is not running that time. Therefore AS3668 supports a special startup
mode shown in Figure 36 and Figure 37 to start up the device without pulling the I²C clock line high. If an external device is connected to the
GPIO/AUDIO_IN pin of AS3668 and the pin is pulled high the device starts up with an default pattern running on CURR1 although the I²C clock
line is low shown in Figure 37. If for example AS3668 starts up with I²C and the GPIO/AUDIO_IN pin is low that time the device starts up in
standby mode and can be configured using the two wire interface. If the I2C signal lines become low whereas the GPIO/AUDIO_IN pin is high at
the same time the chip keeps activated and running as long as GPIO/AUDIO_IN pin is high. Once the GPIO/AUDIO_IN pin goes low the device
enters shut down mode. This use case enables the user to keep on charging the battery for example and indicate this with a special PWM
pattern while the CPU is powered down for example. A typical application is shown in Figure 38.
www.ams.com/AS3668
Revision 1.13
27 - 59