Bclk[1:0] Frequency Select; 100 Mhz Operation - Intel 82850 Chipset; Figure 16. Bclk[1:0] Frequency Select For 100 Mhz System Bus Operation - Intel Pentium 4 Design Manual

Platform Clock Routing Guidelines
4.2

BCLK[1:0] Frequency Select

4.2.1 100 MHz Operation – Intel
The BCLK[1:0] frequency should be set for 100 MHz operation for the 82850 chipset. This is
accomplished with a 470 Ω pull-down on the CK-00 SEL100/133 input. In addition, the platform
should be prevented from operating with a processor that requires a BCLK[1:0] frequency other
than 100 MHz. The correct frequency select circuitry is show in Figure 16.

Figure 16. BCLK[1:0] Frequency Select for 100 MHz System Bus Operation

Processor
46
3.3V
1kΩ
BSEL0
® ®
Intel Pentium 4 Processor / Intel
®
82850 Chipset
3.3V
1kΩ
470Ω
®
850 Chipset Family Platform Design Guide
CK-00
PWRDWN#
SEL 100/133
BCLK_Freq_Sel
R