SE555: SE555

user4345944

Part Number: SE555
Other Parts Discussed in Thread: LMC555, TLC555

Hi,

I am using this part in the astable circuit below. I would like to know what are the consequences of not connecting the discharge pin (as on the app notes in the datasheet it is always connected).

Thanks in advance for your help.

Best regards,

Annaïs

over 6 years ago

0 Ron Michallick over 6 years ago

TI__Guru**** 166486 points

Annias,

Pin 7 can be left open. Pin3 output does not swing up to VCC (pin 8) voltage, so output won't be 50% and duty cycle will vary with VCC voltage. Be sure to add 0.1uF bypass from pin 8 to pin 1.

TLC555 and LMC555 timer will be close to 50%duty cycle but it is better to increase resistor to 10k.

0 user4345944 over 6 years ago in reply to Ron Michallick

Intellectual 290 points

Thanks for your answer Ron.

Best regards,

Annais

Clock & timing

Clock & timing forum

SE555: SE555