Datasheet

KSZ8081RNA/RND
DS00002199A-page 44  2016 Microchip Technology Inc.
10.0 REFERENCE CLOCK - CONNECTION AND SELECTION
A crystal or external clock source, such as an oscillator, is used to provide the reference clock for the KSZ8081RNA/
RND. For the KSZ8081RNA/RND in RMII – 25 MHz clock mode, the reference clock is 25 MHz. The reference clock
connections to XI (Pin 8) and XO (Pin 7), and the reference clock selection criteria, are provided in Figure 10-1 and
Table 10-1.
FIGURE 10-1: 25 MHZ CRYSTAL/OSCILLATOR REFERENCE CLOCK CONNECTION
Note 10-1 ±60 ppm for overtemperature crystal.
For the KSZ8081RNA/RND in RMII – 50 MHz clock mode, the reference clock is 50 MHz. The reference clock connec-
tion to XI (Pin 8), and the reference clock selection criteria are provided in Figure 10-2 and Table 10-2.
FIGURE 10-2: 50 MHZ OSCILLATOR/REFERENCE CLOCK CONNECTION
TABLE 10-1: 25 MHZ CRYSTAL/REFERENCE CLOCK SELECTION CRITERIA
Characteristics Value
Frequency 25 MHz
Frequency Tolerance (max.); Note 10-1 ±50 ppm
Crystal Series Resistance (typ.) 40
Crystal Load Capacitance (typ.) 16 pF
TABLE 10-2: 50 MHZ OSCILLATOR/REFERENCE CLOCK SELECTION CRITERIA
Characteristics Value
Frequency 50 MHz
Frequency Tolerance (max.) ±50 ppm
NC
XI
XO
25MHz OSC
±50ppm
XI
XO
25MHz XTAL
±50ppm
22pF
22pF
NC
XI
XO
50MHz OSC
±50ppm