Locally Generated Voltage Reference Divider Circuit; Ich4-M Single Generated Voltage Reference Divider Circuit; Figure 68. Single Vref/Vswing Voltage Generation Circuit For Hub Interface; Table 62. Recommended Resistor Values For Single Vref/Vswing Divider Circuit - Intel 852GM Design Manual

R

Figure 68. Single VREF/VSWING Voltage Generation Circuit for Hub Interface

The resistor values, R1, R2, and R3 must be rated at 1% tolerance. See Table 62 for recommended
resistor value. The selected resistor values ensure that the reference voltage tolerance is maintained over
the input leakage specification. Two 0.1-µF capacitors (C1 and C3) should be placed close to the
divider. In addition, the 0.01-µF bypass capacitor (C2, C4, C5, and C6) should be placed within
0.25 inches of HLVREF/VREF pin (for C4 and C6) and HI_VSWING pin (for C2 and C5).

Table 62. Recommended Resistor Values for Single VREF/VSWING Divider Circuit

Option 1
Option 2
Option 3
9.3.2.

Locally Generated Voltage Reference Divider Circuit

Sections 9.3.2.1 and 9.3.2.2 provide the option to generate the voltage references separately for GMCH
and ICH4-M. This option should be used if the routing distance between GMCH and ICH4-M is greater
than 4 inches.
9.3.2.1.

ICH4-M Single Generated Voltage Reference Divider Circuit

This option allows the ICH4-M to use one voltage divider circuit to generate both HIVREF and
HI_VSWING voltage references. The reference voltage for both HIVREF and HI_VSWING must meet
the voltage specification in Table 61. The resistor values R1, R2, and R3 must be rated at 1% tolerance
(see Table 62). Normal care needs to be taken to minimize crosstalk to other signals (< 10-15 mV). If
the voltage specifications are not met then individually generated voltage divider circuit for HIVREF
and HI_VSWING is required.
®
Intel 852GM Chipset Platform Design Guide
PSWING
GMCH
HLVREF
Recommended Resistor Values
R1 = 80.6 Ω ± 1%
R1 = 255 Ω ± 1%
R1 = 226 Ω ± 1%
C1 and C3 = 0.1 µF (near divider)
C2, C4, C5, C6 = 0.01 µF (near component)
VCCHI
R1
HI_VSWING
C5 C2
ICH4-M
R2
C1
HIREF
C4
C6
R3
C3
R2 = 51.1 Ω ± 1% R3 = 40.2 Ω ± 1%
R2 = 162 Ω ± 1% R3 = 127 Ω ± 1%
R2 = 147 Ω ± 1% R3 = 113 Ω ± 1%
Hub Interface
VCCHI
1.5 V
1.5 V
1.5 V
149