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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.