Measurement Computing USB-1608FS - Manual (Page 21)

USB-1608FS User's Guide
21
External trigger
Table 6. External trigger specifications
Parameter Condition 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 1µs min
Input type Schmitt trigger, 47 k
Ω 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 7. External clock I/O specifications
Parameter Condition Specification
Pin name SYNC
Pin type Bidirectional
Direction, software-selectable Input Receives A/D pacer clock from external source
Output Outputs internal A/D pacer clock
Input clock rate 50 kHz, maximum
Clock pulse width Input 1µs min
Output 5µs min
Input clock mode Edge sensitive: rising edge
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)