User Manual

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)