Ultra Ata/66 Pullup/Pulldown Requirements; Resistor Requirements For Primary Ide Connector - Intel VC820 - Desktop Board Motherboard Design Manual

Layout/Routing Guidelines
2.13.3

Ultra ATA/66 Pullup/Pulldown Requirements

22 Ω – 47 Ω series resistors are required on RESET#. The correct value should be determined
•
for each unique motherboard design, based on signal quality.
•
An 8.2 KΩ to 10 KΩ pull-up resistor is required on IRQ14 and IRQ15 to VCC5.
•
A 10 KΩ pull-down resistor is required on PDD7 and SDD7 (as required by the ATA-4
specification).
•
A 5.6 KΩ pull-down resistor is required on PDDREQ# and SDDREQ# (as required by the
ATA-4 specification).
A 1K Ω pull-up resistor is required on PIORDY and SIORDY (as required by the ATA-4
•
specification).
Figure 2-50. Resistor Requirements for Primary IDE Connector
2-60
PCIRST_BUF#*
PDD[15:8]
PDD[7]
PDD[6:0]
PDA[2:0]
PDCS1#
PDCS3#
PDIOR#
PDIOW#
PDDREQ
5V
1k
ohm
PIORDY
IRQ14
PDDACK#
ICH
*Due to ringing, PCIRST# must be buffered.
5V
10k
5.6k
ohm
8.2k-10k ohm
ohm
22 - 47 ohm
Reset#
470 ohm
CSEL
Pin 32
N.C.
Pin 34
N.C.
®
Intel 820 Chipset Design Guide