External trigger, External clock input/output – Measurement Computing USB-1408FS User Manual
Page 23
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USB-1408FS User's Guide
Specifications
23
External trigger
Table 10. External digital trigger specifications
Parameter
Conditions
Specification
Trigger source
External, digital
TRIG_IN
Trigger mode
Software-selectable
Edge sensitive: user configurable for CMOS compatible rising or
falling edge
Trigger latency
10 µs max
Trigger pulse width
1 µs min
Input type
Schmitt trigger, 47 kΩ pull-down to ground
Schmitt trigger
hysteresis
1.01 V typ
0.6 V min
1.5 V max
Input high voltage
threshold
2.43 V typ
1.9 V min
3.1V max
Input high voltage limit
5.5 V absolute max
Input low voltage
threshold
1.42 V typ
1.0 V min
2.0 V max
Input low voltage limit
-0.5 V absolute min
0 V recommended min
External clock input/output
Table 11. External clock I/O specifications
Parameter
Conditions
Specification
Pin name
SYNC
Pin type
Bidirectional
Direction
(software-selectable)
Output
Outputs internal A/D pacer clock. Active on rising edge.
Input (default)
Receives A/D pacer clock from external source. Active on rising edge.
Input clock rate
48 kHz, maximum
Clock pulse width
Input mode
1 µs min
Output mode
5 µs min
Input type
Schmitt trigger, 47
kΩ pull-down to ground
Schmitt trigger
hysteresis
1.01 V typ
0.6 V min
1.5 V max
Input high voltage
threshold
2.43 V typ
1.9 V min
3.1V max
Input high voltage limit
5.5 V absolute max
Input low voltage
threshold
1.42 V typ
1.0 V min
2.0 V max
Input low voltage limit
-0.5 V absolute min
0 V recommended min
Output high voltage
4.4 V min (IOH = –50 µA)
3.80 V min (IOH = –8 mA)
Output low voltage
0.1 V max (IOL = 50 µA)
0.44 V max (IOL = 8 mA)