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Chapter 3 Signal Connections
© National Instruments Corporation 3-17 PCI-1200 User Manual
Logical Inputs and Outputs
• Absolute max voltage rating –0.5 to +5.5 V with respect to DGND
• Digital I/O lines:
– Input logic low voltage –0.3 V min 0.8 V max
– Input logic high voltage 2.2 V min 5.3 V max
– Output logic low voltage — 0.4 V max
(at output current = 2.5 mA)
– Output logic high voltage 3.7 V min —
(at output current = –2.5 mA)
– Input leakage current –1 µA min 1 µA max
(0 < V
in
< 5 V)
Figure 3-8 illustrates signal connections for three typical digital I/O
applications.
Figure 3-8.
Digital I/O Connections
In Figure 3-8, port A is configured for digital output, and ports B and C are
configured for digital input. Digital input applications include receiving
TTL signals and sensing external device states such as the switch in
TTL Signal
13
DGND
I/O Connector
PCI-1200
30 PC0
22 PB0
+5 V
+5 V
LED
14 PA0
Port A
PA<7..0>
Port B
PB<7..0>
Port C
PC<7..0>