• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 18 subscribers
  • Views 415 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CD4541B: Duty cycle in recycle mode

Matthew Thode
Prodigy 10 points
Part Number: CD4541B
Other Parts Discussed in Thread: NE555, SN74LVC1G123

Hello, first of all I will give you the warning that building circuits is relatively new to me. I have a good basic understanding of passive components, but I'm still learning about ICs and integration So go easy on me!

I am trying to build a basic LED strobe light using a CD4541B. I started out using a NE555 but was not able to get the desired "strobe" effect due to the duty cycle not going below 50%.

I'm planning to run it with Auto-reset and Recycle Mode ON, and Pin 9 set to Q (output initially low after reset). I'll set the RC and Frequency so I get roughly 10 hz.

My question is as follows: What is the high and low time of the output throughout the cycle? Or in other words, what is the duty cycle of the output in this configuration?

As a follow-up question, can you think of a better chip to accomplish this? Thanks!

  • 0
    TI__Guru* 96712 points
    Hey Matthew,
    The CD4541B is really designed to produce a clock (50% duty cycle) and divide it down to get several output frequencies

    I would recommend a combination of 2 chips -- the first is the 555 timer to get your base frequency (using a potentiometer you can make that adjustable quite easily). Then you can feed that 50% duty cycle clock signal into a monostable multivibrator like the SN74LVC1G123. This device is also known as a "one shot" and will produce a short pulse of preprogrammed width (determined by two external components, one R and one C). If you want a very fast flash (say, 10ms) then a good set of values to start with would be C = 1uF and R = 10kohm (also could be replaced with a pot for easy adjustment). The output pulse width will be roughly R*C (there's also a 'k' factor that will change the actual pulse width a bit).