SN74CB3T16210 (FET Switch) VCC supply question

JaeKyung Shin

Prodigy 230 points

Other Parts Discussed in Thread: SN74CB3T16210

I design bus 2.5V <--> 3.3V

by figure 3 of SN74CB3T16210 datasheet , I think Vout = Vcc-0.2 (at VI<VCC+1)

but in figure 4, Vout may down to VCC - 0.7 and if Vcc = 2.5V, 3.3V device can't reconize HIGH.

I read some of application note and I think Vcc = 2.5V is correct (in 2.5V bus<--> 3.3V bus)

but, previous design in my company(isn't my design), Vcc = 3.3V and It working correct!

What voltage of vcc is correct? 2.5V? 3.3V?

over 12 years ago

0 Chris Cockrill over 12 years ago

TI__Mastermind 46480 points

Hi JaeKyung

The CB3T devices are made to translate down and the input voltage should be 1V higher then Vcc in order for it to work correctly. They will translate down to Vcc.

If you are translating 3.3v to 2.5V then Vcc should be 2.5V. Even though it is not quite a Volt above Vcc it will still work.

If you need it to translate up then you must use a pullup on the output.

0 JaeKyung Shin over 12 years ago in reply to Chris Cockrill

Prodigy 230 points

Thanks you very much.

I wondered this question very long time.

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SN74CB3T16210 (FET Switch) VCC supply question