Intel Xeon Processor and Intel E7500/E7501Chipset Compatible Platform Design Guide
Schematic Checklist
234 Intel
®
 Xeon™ Processor and Intel
®
 E7500/E7501 Chipset Compatible Platform Design Guide
Host Side / Device 
Side Cable 
Detection
• Connect IDE pin PDIAG#/CBLID# to an 
ICH3-S GPI pin. Connect a 10 k
Ω resistor to 
ground on the signal line. 
• The 10 k
Ω resistor to ground 
prevents GPI from floating if no 
devices are present on either 
IDE interface. Allows use of 
3.3 V and 5 V tolerant GPIOs.
• Refer to Section 9.1.2.1.
Interrupt Interface
APICCLK • Pull-down directly to ground.
APICD[1:0] •  10 k
Ω ± 5% pull-down to ground.
PIRQ[D:A]# • These signals require a pull-up resistor.
•2.7 k
Ω ± 5% pull-up to 5 V or an 8.2 kΩ± 
5%
 pull-up to 3.3 V. 
• Each PIRQx# line has a 
separate Route Control 
Register. In APIC mode, these 
signals are connected to the 
internal I/O APIC in the 
following fashion: 
– PIRQ[A]# is connected to 
IRQ16.
– PIRQ[B]# is connected to 
IRQ17.
– PIRQ[C]# is connected to 
IRQ18.
– PIRQ[D]# is connected to 
IRQ19. 
This frees the ISA interrupts.
PIRQ[H:E]#/
GPIO[5:2]
• These signals require a pull-up resistor.
•2.7 k
Ω ± 5% pull-up to VCC_5 or an 
8.2 k
Ω± 5% pull-up to 3.3 V. 
• These signals are connected to 
the internal I/O APIC in the 
following fashion: 
– PIRQ[E]# is connected to 
IRQ20.
– PIRQ[F]# is connected to 
IRQ21.
– PIRQ[G]# is connected to 
IRQ22.
– PIRQ[H]# is connected to 
IRQ23. 
This frees the ISA interrupts.
SERIRQ •  8.2 k
Ω ± 5% pull-up to 3.3 V. • Open drain signal.
LAN Interface
LAN_CLK, 
LAN_RXD[2:0], 
LAN_TXD[2:0], 
LAN_RSTSYNC
• Connect to Platform LAN Connect Device.  • Refer to Section 9.7.
• LAN Connect Interface Signals 
can be left as NC if not used 
because the Input buffers are 
internally terminated.
Miscellaneous Signals
SPKR • No extra pull-up resistors. • Refer to Section 9.2.
TP[0] • 8.2 k
Ω – 10 kΩ pull-up to VCCSUS3_3.
AC_SDOUT • No extra pull-down needed. • This ball has a weak internal 
pull-down.
Table 13-3. Intel
®
 ICH3-S Schematic Checklist (Sheet 3 of 6)
Checklist Items Recommendations Comments










