chenx
Joined: 20 Nov 2001
Posts: 4
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 06 Dec 2001 2:36 |
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Hello Jerry_chan,
If you look at the datasheet you'll see the specs. of VOH:
if VCC = 2.7 V to 3.6 V,(IOH=–100 µA) VOH = VCC–0.2 V
Therefore you'll have 3.3V - 0.2V = 3.1V min to Vcc(3.3V) max. at the output pin
Pay attention about the variation
(decreasing) of VOH when IOH grows.
In most cases this voltage is enough to drive other 5V devices, but if you want to ensure a reliable performance, you can try with the dual supply voltage level shifter 74ALVC164245 by Phillips semiconductor:
http://www.philipslogic.com/products/levelshifters/all/
As you can see it has 2 VCC inputs.
Otherwise I made use of the 74LVC245 to mix 5V logic & 3.3V logic and worked fine...
Best rgrds,
Chenx
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