A CPLD-based long-duration pulse generator

which can generate singular or continuous pulse with ul- tra-low repetition rate /long cycle

is introduced in this paper. The cycle (T) of output pulses generated by this genera- tor can be selected in a range from Tmin=1 ms to Tmax>1000 s. Also

the width of the output pulse can be adjusted from 1/1000 cycle to 999/1000 cycle stepped by 1/1000 cycle. Accuracy of the repetition rate(f) of output pulses is <0.02‰

and the long-term instability of is within ±0.01‰. There are two modes selectable for output pulses

singular pulse output and repetitive pulse output

which can be set by a two-position switch. When the singular pulse output mode is selected

only one pulse can be generated each time by pressing an external control push-button. This pulser can provide both TTL / TTL output signals and NIM / NIM output signals. The risetime of the NIM output signal is tr<4ns and the falltime is tf<4ns. We use CPLD to construct the main circuits. Compared with the circuits constructed by TTL devices

the new pulse generator has features such as less components

lower cost and lower dis- sipation.