NA555: Do NA555 support 3.3V input?

Yishan Chen

Intellectual 1720 points

Part Number: NA555
Other Parts Discussed in Thread: TLC555

Tool/software:

Hi Team,

Customer use 3.3V input to generate simlar 3.3V output.

They find the device also work, but our datasheet is 5V, want to double check with you if our NA555 support 3.3V input.

If not support 3.3V input, why the device still works?

Thank you,

Yishan Chen

2 months ago

0 Ron Michallick 2 months ago

TI__Guru**** 164956 points

Hello Yishan,

3.3V not compliant with data sheet specification, so very risky. TLC555 is pin to pin compatible and supports 3.3V; it is also faster.

0 Yishan Chen 2 months ago in reply to Ron Michallick

TI__Intellectual 1720 points

Hi Ron,

Since NA555 is not support 3.3V and it is hard for customer to change BOM at this time.

So I need to bring back this thread.

https://e2e.ti.com/support/clock-timing-group/clock-and-timing/f/clock-timing-forum/1508430/na555-rl-connected-to-mcu-power-rail/5833905?tisearch=e2e-sitesearch&keymatch=%25252520user%2525253A530823#

When they didn't connect to the load, the output waveform is good. But when they connect to the MCU IO, the frequency is change to 510Khz and the low level signal is 190mV, can't go down to 0. Do we have any move can achieve stable 500Khz switching frequency and 3.3/0 H/L signal?

Load disconnected:

Load connected:

The load is MCU IO with 3.3V+10K external pull up circuit.

Thank you,

Yishan Chen

Clock & timing

Clock & timing forum

NA555: Do NA555 support 3.3V input?