23
Terminations
Terminations
3
This chapter provides the recommended pull-up and pull-down terminations for a 80331 layout.
lists these 80331 termination values. On a motherboard, the
PCI Local Bus Specification
,
Revision 2.3 requires that the PCI signals provide the termination resistors. Pull-ups on the PCI
signals are not required with PCIODT_EN = 1 (enabled), because they are implemented on the die.
Refer to the
for more information.
Table 3.
Terminations: Pull-up/Pull-down (Sheet 1 of 4)
Signal
Pull-up or Pull-down
Resistor Value (in Ohms)
Comments
PWRDELAY
If battery backup is
implemented:
•
1.5 K pull-up to 3.3 V is
required on
PWRDELAY.
Battery Backup not
implemented:
•
This pin can be
permanently pulled low
with a 1.5K pull-down
TRST#
1.5K pull-down*
NOTES:
•
Alternatively tied to
P_RST#
refer to
for more information about using with a
ICE.
•
When not used this signal is be tied to GND.
•
This pin has an internal pull-up.
TMS
NC when not being used
(has internal pull-up)
TDI
NC when not being used
(has internal pull-up)
TCK
1.5K pull-down when not
used
GPIO[0]/U0_RXD
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[1]/U0_TXD
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[2]/U0_CTS#
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[3]/U0_RTS#
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[4]/U1_RXD
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[5]/U1_TXD
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[6]/U1_CTS#
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
GPIO[7]/U1_RTS
8.2 K pull-up
Note:
GPIO[7:0]
initializes as inputs on assertion of
P_RST#
.
ARB_EN
(see comments)
This signal has been defeatured. Please refer to the Intel® 80331
Specification Update for more information.
Summary of Contents for 80331
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