5.2 Clock

The IS2083BM SoC is composed of an integrated crystal oscillator that uses a 16 MHz ±10 ppm external crystal and two specified loading capacitors to provide a high-quality system reference timer source. This feature is typically used to remove the initial tolerance frequency errors, which are associated with the crystal and its equivalent loading capacitance in the mass production. Frequency trim is achieved by adjusting the crystal loading capacitance through the on-chip trim capacitors (Ctrim).

The crystal trimming can be done using manufacturing tools provided by Microchip. The following figure illustrates the crystal oscillator connection of the IS2083BM SoC with two capacitors.

Figure 5-2. Crystal Oscillator in the IS2083BM
The clock module controls switching and synchronization of clock sources. Clock sources include:
  • System Phase-locked Loop (PLL)
  • Primary oscillator
  • External clock oscillator
  • Ultra Low-power internal RC oscillator (UPLC) with nominal frequency as 32 kHz.
The clock module provides gated clock output for 8051 and its peripheral modules, gated clock output for Bluetooth modules as well as DSP audio subsystem. The system enters low power mode by switching OFF clocks driven from the PLL and external oscillator. Only ULPC is operated to maintain Bluetooth timing.