Oscillators; Figure 14.1. Oscillator Diagram - Silicon Laboratories C8051F341 Product Manual

14. Oscillators

C8051F34x devices include a programmable internal high-frequency oscillator, a programmable internal
low-frequency oscillator (C8051F340/1/2/3/4/5/8/9/A/B/C/D), an external oscillator drive circuit, and a 4x
Clock Multiplier. The internal high-frequency and low-frequency oscillators can be enabled/disabled and
adjusted using the special function registers, as shown in Figure 14.1. The system clock (SYSCLK) can be
derived from either of the internal oscillators, the external oscillator circuit, or the 4x Clock Multiplier divided
by 2. The USB clock (USBCLK) can be derived from the internal oscillator, external oscillator, or 4x Clock
Multiplier. Oscillator electrical specifications are given in Table 14.1.
Option 2
Option 3
VDD
XTAL2
XTAL2
Option 1
XTAL1
10M
XTAL2
Option 4
XTAL2
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
OSCICL OSCICN
EN
IOSC
Programmable High-
Frequency Oscillator
OSCLF3-0
EN
Programmable Low-
Frequency Oscillator
(C8051F340/1/2/3/4/5/8/9/
A/B/C/D)
EXOSC
Input
OSC
Circuit
IOSC
EXOSC
EXOSC / 2
OSCXCN CLKMUL

Figure 14.1. Oscillator Diagram

Rev. 1.3
OSCLCN CLKSEL
n
n
x 2 x 2
IOSC / 2
Clock Multiplier
EXOSC
EXOSC / 2
EXOSC / 3
EXOSC / 4
SYSCLK
USBCLK
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