C8051F040 View Datasheet(PDF) - Silicon Laboratories
Part Name
Description
MFG CO.
'C8051F040' PDF : 328 Pages View PDF
C8051F040/1/2/3/4/5/6/7
14. Oscillators
Option 3
XTAL1
XTAL2
Option 4
XTAL1
Option 2
VDD
XTAL1
Option 1
XTAL1
XTAL2
OSCICL
OSCICN
CLKSEL
EN
Programmable
Internal Clock
Generator
Input
Circuit
OSC
n
0
SYSCLK
1
OSCXCN
Figure 14.1. Oscillator Diagram
14.1. Programmable Internal Oscillator
All C8051F04x devices include a programmable internal oscillator that defaults as the system clock after a
system reset. The internal oscillator period can be programmed via the OSCICL register as defined by
SFR Definition 14.1. OSCICL is factory calibrated to obtain a 24.5 MHz frequency.
Electrical specifications for the precision internal oscillator are given in Table 14.1 on page 175. The pro-
grammed internal oscillator frequency must not exceed 25 MHz. The system clock may be derived from
the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register OSCICN.
Rev. 1.5
173
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