I'm trying to create a ~0.25 second pulse from a leading edge trigger. I found the TI CD4098B chip (datasheet: http://www.ti.com/lit/ds/symlink/cd4098b.pdf) that shows a circuit in the datasheet that will do just what I need (leading edge non-retriggerable pulse). However, I am not able to get the chip to work.
When I trigger the +TR input with 5V (VDD) or with ground (VSS), the output Q-bar goes to 5V. It seems as long as the trigger input is not floating, the output is 5V. But more importantly, there is no output pulse. I can't get the output to give me the 0.25s pulse I need.
With the input floating, the output is around 0.6V.
Here is my circuit which, as far as I can tell, is exactly what it shows in the datasheet.
Pin 1: NC
Pin 2: NC
Pin 3: Vss (gnd)
Pin 4: Vss (gnd)
Pin 5: Vdd (5V)
Pin 6: NC
Pin 7: NC
Pin 8: GND
Pin 9: to pin 11, and output Q-bar
Pin 10: NC
Pin 11: to pin 9
Pin 12: input
Pin 13: Vdd (5V)
Pin 14: cap to pin 15 and resistor to Vdd
Pin 15: cap to pin 14
Pin 16: 5V
R=47k, C=10uF -> time ~0.25s
When I trigger the +TR input with 5V (VDD) or with ground (VSS), the output Q-bar goes to 5V. It seems as long as the trigger input is not floating, the output is 5V. But more importantly, there is no output pulse. I can't get the output to give me the 0.25s pulse I need.
With the input floating, the output is around 0.6V.
Here is my circuit which, as far as I can tell, is exactly what it shows in the datasheet.
Pin 1: NC
Pin 2: NC
Pin 3: Vss (gnd)
Pin 4: Vss (gnd)
Pin 5: Vdd (5V)
Pin 6: NC
Pin 7: NC
Pin 8: GND
Pin 9: to pin 11, and output Q-bar
Pin 10: NC
Pin 11: to pin 9
Pin 12: input
Pin 13: Vdd (5V)
Pin 14: cap to pin 15 and resistor to Vdd
Pin 15: cap to pin 14
Pin 16: 5V
R=47k, C=10uF -> time ~0.25s