LMC555 / alternating frequency

Kato,

I can help you with a NE555 or NE556 design. I believe no switched components will be needed. 

It will be easier if 50% duty cycle is not required or a divide by two flip flop can be use to get 50% duty cycle.
Does it matter if the switch point every 50mS has a pulse that is neither frequency because 100mS clock not being synchronized with carrier clock? 

Hi Ron - san,

Thank you for the reply. The 100ms clock don't need to synchronize with carrier clock. In addition, customer requires VCC=3.3V devices. Please let me know if there are any suggested solutions.

Best Regards,

Kato

Hi Ron - san,

Would you provide us some comments for my solution to customer system as follows.

Please let me know if there are any problems.

Best Regards,

Kato

Kato san,

For 3.3V supply. I recommend TLC555 timer. It is a low voltage version of the NE555 and LMC555 timers.

Your idea behind your design is good. You can use higher value resistor to save power. 10 times the values should be good.

The placement of the switch allows PNP or PMOS switch to be used as the switch.

The reset pin can be used to turn off the signal if needed. 

You may also choose to use TLC556 dual timer to move the 100 ms task from the CPU to the second timer.

Hi Ron - san,

Thank you for your advice. However, I think LMC555 is lower voltage version than TLC555. Is TLC555 recommended device for 3.3V supply?

In addition, if TLC556 is selected, please let me know how to create 100ms clock to change from 1319Hz to 1760Hz.

Best Regards,

Kato

Hi Ron - san,

Thank you for your kind support. I understood the solution with TLC555/556/LMC555

Best Regards,

Kato