Advantech SOM-ETX Design Guide
2.5.2 Interface I/O Voltage
2.5.2.1 PCI Bus
Table 2.47 DC specifications for 5V signaling of PCI Bus
Symbol Parameter Min
Max
Units
Note
Vcc
Supply Voltage
4.75
5.25
V
Vih
Input High Voltage
2.0
Vcc+0.5
V
Vil
Input Low Voltage
-0.5
0.8
V
Voh
Output High Voltage
2.4
-
V
Vol
Output Low Voltage
-
0.55
V
*1
*1. Signals without pull-up resistors must have 3 mA low output current. Signals
requiring pull up must have 6 mA; the latter include, FRAME#, TRDY#, IRDY#,
DEVSEL#, STOP#, SERR#, PERR#, LOCK#, INTA#, INTB#, INTC#, INTD#.
Table 2.48 DC specifications for 3.3V signaling of PCI Bus
Symbol Parameter Min
Max
Units
Note
Vcc
Supply Voltage
3.0
3.6
V
Vih
Input High Voltage
0.5Vcc
Vcc+0.5
V
Vil
Input Low Voltage
-0.5
0.3Vcc
V
Vipu
Input Pull-up Voltage
0.7Vcc
-
V
*1
Voh
Output High Voltage
0.9Vcc
-
V
Vol
Output Low Voltage
-
0.1Vcc
V
*1. This specification should be guaranteed by design. It is the minimum voltage to which pull-
up resistors are calculated to pull a floated network. Applications sensitive to static power
utilization must assure that the input buffer is conducting minimum current at this input
voltage.
2.5.2.2 Universal Serial Bus (USB)
Table 2.49 DC specification of USB signals
Symbol Parameter
Min
Max
Unit
Note
V
bus
High-power port supply voltage
4.75
5.25
V
V
bus
Low-power port supply voltage
4.75
5.25
V
V
IL
Input Low Voltage
-
0.8
V
V
IH
Input High Voltage(driven)
2.0
-
V
V
IHZ
Input High Voltage(floating) 2.7
3.6 V
V
OL
Output Low Voltage
0
0.3
V
V
OH
Output High Voltage
2.8
3.6
V
46
Chapter 2 SOM-ETX Overview
