C8051F000DK-E Silicon Laboratories Inc, C8051F000DK-E Datasheet - Page 99

• Manufacturer Part Number: C8051F000DK-E
• Description: DEV KIT FOR C8051F000/F001/F002
• Manufacturer: Silicon Laboratories Inc

Specifications of C8051F000DK-E

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

14. OSCILLATOR
Each MCU includes an internal oscillator and an external oscillator drive circuit, either of which can generate the
system clock. The MCUs boot from the internal oscillator after any reset. The internal oscillator starts up instantly.
It can be enabled/disabled and its frequency can be changed using the Internal Oscillator Control Register
(OSCICN) as shown in Figure 14.2. The internal oscillator’s electrical specifications are given in Table 14.1.
Both oscillators are disabled when the /RST pin is held low. The MCUs can run from the internal oscillator or
external oscillator, and switch between the two at will using the CLKSL bit in the OSCICN Register. The external
oscillator requires an external resonator, parallel-mode crystal, capacitor, or RC network connected to the
XTAL1/XTAL2 pins (see Figure 14.1). The oscillator circuit must be configured for one of these sources in the
OSCXCN register. An external CMOS clock can also provide the system clock via overdriving the XTAL1 pin.
The XTAL1 and XTAL2 pins are 3.6V (not 5V) tolerant. The external oscillator can be left enabled and running
even when the MCU has switched to using the internal oscillator.
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C8051F000/1/2/5/6/7
C8051F010/1/2/5/6/7
opt. 4
XTAL1
opt. 3
XTAL1
XTAL2
AV+
opt. 2
XTAL1
opt. 1
XTAL1
XTAL2
AGND
Figure 14.1. Oscillator Diagram
VDD
AV+
Circuit
Input
OSCXCN
Internal Clock
OSCICN
Generator
EN
OSC
Rev. 1.7
SYSCLK