Product Specs

19 CLOCK — Clock control
Page
101
HFCLKSTART HFCLKSTOP
LFCLKSTAR T LFCLKSTOP
CLOCK
XC1
XC2
XL1
XL2
HFCLKSTARTED
LFCLKSTARTED
LFCLK
Clock control
LFXO
Crystal oscillator
SYNT
LFRC
RC oscillator
CAL
HFXO
Crystal oscillator
HFCLK
Clock control
HFINT
Internal oscillator
19 CLOCK — Clock control
The clock control system can source the system clocks from a range of internal or external high and low
frequency oscillators and distribute them to modules based upon a module’s individual requirements. Clock
distribution is automated and grouped independently by module to limit current consumption in unused
branches of the clock tree.
Listed here are the main features for CLOCK:
• 64 MHz on-chip oscillator
• 64 MHz crystal oscillator, using external 32 MHz crystal
• 32.768 kHz +/-250 ppm RC oscillator
• 32.768 kHz crystal oscillator, using external 32.768 kHz crystal
• 32.768 kHz oscillator synthesized from 64 MHz oscillator
• Firmware (FW) override control of oscillator activity for low latency start up
• Automatic oscillator and clock control, and distribution for ultra-low power
32 MHz
PCLK1M
PCLK16M
PCLK32M
HCLK64M
32.768 kHz PCLK32KI
Figure 17: Clock control
19.1 HFCLK clock controller
The HFCLK clock controller provides the following clocks to the system.
• HCLK64M: 64 MHz CPU clock
• PCLK1M: 1 MHz peripheral clock
• PCLK16M: 16 MHz peripheral clock
• PCLK32M: 32 MHz peripheral clock
The HFCLK controller supports the following high frequency clock (HFCLK) sources:
• 64 MHz internal oscillator (HFINT)
• 64 MHz crystal oscillator (HFXO)
For illustration, see Figure 17: Clock control on page 101.