Measurement Computing USB-1808X, User Manual

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USB-1808X User's Guide Specifications
23
Timer
Table 13. Timer specifications
Parameter Specification
Terminal name TMR0, TMR1
Timer type PWM output with count, period, delay, and pulse width registers
Output value Default state is idle low with pulses high, software-selectable output invert
Trigger source OTRIG (see External trigger on page 24)
Internal clock frequency 100 MHz
Register widths 32-bit
High pulse width 10 ns min
Low pulse width 10 ns min
Output high voltage 4.4 V min (IOH = –50 µA)
3.76 V min (IOH = –2.5 mA)
Output low voltage 0.1 V max (IOL = 50 µA)
0.44 V max (IOL = 2.5 mA)
Output current ±2.5 mA max
External clock input/output
Table 14. External clock I/O specifications
Parameter Specification
Terminal names ICLKI, ICLKO
OCLKI, OCLKO
Terminal types xCLKI: Input, active on rising edge
xCLKO: Output, power on default is 0 V, active on rising edge
Terminal descriptions xCLKI: Receives sampling clock from external source
xCLKO: Outputs the internal input scan or internal output scan clock, or the
pulse generated from xCLKI when in external clock mode.
Input clock rate 500 kHz max
Clock pulse width xCLKI: 400 ns min
xCLKO: 400 ns min
Input type Schmitt trigger, 33 Ω series resistor, 47 kΩ pull -down to ground
Schmitt trigger hysteresis 0.4 V to 1.2 V
Input high voltage 2.2 V min
5.5 V absolute max
Input low voltage 1.5 V max
–0.5 V absolute min
0 V recommended min
Output high voltage 4.4 V min (IOH = –50 µA)
3.76 V min (IOH = –2.5 mA)
Output low voltage 0.1 V max (IOL = 50 µA)
0.44 V max (IOL = 2.5 mA)
Output current ±2.5 mA max