Schematic Review Checklist
R
Intel
®
Pentium
®
4 Processor / Intel
®
850 Chipset Family Platform Design Guide 253
15.5 AGP Checklist
Checklist Items Recommendations Reason/Impact
G_FRAME#
G_IRDY#
G_TRDY#
G_DEVSEL#
G_STOP#
G_SERR#
G_PERR#
G_RBF#
G_PIPE#
G_REQ#
G_GNT#
G_PAR
AD_STB[0:1]
SB_STB
WBF#
• These signals require pull-up resistors
to V
DDQ
.
• Acceptable values are between 4 kΩ
and 16 k
Ω. The recommended value
is 8.2 k
Ω.
• V
DDQ
= 1.5 V for 1X, 2X and 4X
mode
• Pull up to V
DDQ
ensures that stable
values are maintained when agents
are not actively driving the bus.
• Refer to Section 7.1.9.
AD_STB#[0:1]
SB_STB#
• These signals require pull-down
resistors.
• Acceptable values are between 4 kΩ
and 16 k
Ω. The recommended value
is 8.2 k
Ω.
• Pull down to GND ensures that
stable values are maintained when
agents are not actively driving the
bus.
• Refer to Section 7.1.9.
INTA#
INTB#
• 8.2 kΩ pull-up resistors to 3.3 V
• Range is 4 kΩ – 16 kΩ
• These signals should be pulled up
only once (for both PCI and AGP).
They should be pulled to 3.3 V and
MUST NOT be pulled to 5 V.
• INTB# is for a two function device
and may not be seen with AGP
down
• Refer to Section 7.1.9 this
document.
VREFCG[B66]
VREFGC[A66]
G_REF[1:0]
• VREFCG should be tied to a resistor
divider near the AGP device.
• VREFGC should be a no connect.
• A 220 Ω – 330 Ω series resistor
should be connected from the voltage
divider network to the G_REF[1:0]
pins on the MCH.
• The V
REF
divider network should be
placed near the AGP interface to
achieve the common mode power
supply effect. A 0.1 µF decoupling
capacitor should be placed near the
G_REF[1:0
• Refer to Section 7.1.7.
TYPEDET# [A2] • Intel 850 chipset only supports 1.5 V
add-in card. Therefore, TYPEDET#
detection on the motherboard is not
required.
• Refer to Section 7.1.6.
PME# • Connect to PCI PME# • This is an open drain signal from
the AGP connector and does not
require pull-up resistor to VCC3_3 if
connected to ICH2.
3.3Vaux
(B24)
• Connect to 3.3V
SB
• May not be seen with AGP down
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