9.3.4 Oscillator

The oscillator frequency can be trimmed by external control of the FREQ_ADJ pin.

To reduce interference problems while using radio receiver tuned within the AM band, the switching frequency can be changed from nominal to higher values. These values should be chosen such that the nominal and the higher value switching frequencies together results in the fewest cases of interference throughout the AM band. The oscillator frequency can be selected by the value of the FREQ_ADJ resistor connected to GND in master mode according to the description in the Recommended Operating Conditions table.

For slave mode operation, turn off the oscillator by pulling the FREQ_ADJ pin to AVDD. This configures the OSC_I/O pins as inputs to be slaved from an external differential clock. In a master/slave system inter channel delay is automatically setup between the switching of the audio channels, which can be illustrated by no idle channels switching at the same time. This will not influence the audio output, but only the switch timing to minimize noise coupling between audio channels through the power supply to optimize audio performance and to get better operating conditions for the power supply. The inter channel delay will be setup for a slave device depending on the polarity of the OSC_I/O connection such that a slave mode 1 is selected by connecting the master device OSC_I/O to the slave 1 device OSC_I/O with same polarity (+ to + and - to -), and slave mode 2 is selected with the inverse polarity (+ to - and - to +).