Temperature Changes; Analog References For 82562Gz(Gx) Designs; Rbias10 And Rbias100 Circuits - Intel 82541PI Design Manual

82541PI(ER) and 82562GZ(GX) Dual Footprint LOM Design Guide
Alternatively, a larger sample population of circuit boards can be used. A larger population will
increase the probability of obtaining the full range of possible variations in dielectric thickness and
the full range of variation in stray capacitance.
Next, the exact same crystal and discrete load capacitors (C1 and C2) must be soldered onto each
board, and the LAN reference frequency should be measured on each circuit board.
The circuit board, which has a LAN reference frequency closest to the center of the frequency
distribution, should be used while performing the frequency measurements to select the appropriate
value for C1 and C2.
3.1.5

Temperature Changes

Temperature changes can cause the crystal frequency to shift. Therefore, frequency measurements
should be done in the final system chassis across the system's rated operating temperature range.
3.2

Analog References for 82562GZ(GX) Designs

There are two inputs, RBIAS10 and RBIAS100, to 82562GZ(GX) devices that require external
resistor connections to bias the internal analog section of the device. These inputs are sensitive to
the resistor value and experimentation is needed to select the correct values for any given layout.
Resistors of 1% tolerance must be used.
Figure 2. RBIAS10 and RBIAS100 Circuits
12
Figure 2 shows an example of one possible design.
82562GZ/GX
6 1 9
1 %
R B IA S 1 0
R B IA S 1 0 0
6 4 9
1 %
Application Note (AP-468)