Clock Generation; Crystal Oscillator; Clock Generator - Intel 80C186XL User Manual

The clock generation and distribution circuits provide uniform clock signals for the Execution
Unit, the Bus Interface Unit and all integrated peripherals. The 80C186 Modular Core Family
processors have additional logic that controls the clock signals to provide power management
functions.
5.1

CLOCK GENERATION

The clock generation circuit (Figure 5-1) includes a crystal oscillator, a divide-by-two counter
and power-save and reset circuitry. See "Power-Save Mode" on page 5-11 for a discussion of
Power-Save mode as a power management option.
Schmitt Trigger
"Squares-up" CLKIN
X1
X2
RES
5.1.1

Crystal Oscillator

The internal oscillator is a parallel resonant Pierce oscillator, a specific form of the common
phase shift oscillator.
CLOCK GENERATION AND POWER
÷ 2 Clock
Clock Divider
Reset Circuitry
Figure 5-1. Clock Generator
CHAPTER 5
MANAGEMENT
Power Save
1
Phase
Drivers
2
To CLKOUT
Internal Reset
Internal
Phase
Clocks
A1519-0A
5-1