how to clip a voltage to 3.3V by switching transistor such a

[blue sky]

The board have a 3.3v refence voltage. Another input voltage can
change from 1.5V to 5.5V, but need to clip to 3.3v.
Vout =Vin (Vin <3.3V)
Vout =3.3v (VIN >=3.3V)
If I want to use Infineon's switching transistor (SMBT3904/SMBT3906),
how to design it? I know its a simple question, I'm just a beginer in
hardware design.
Any tips is welcome.

 

[artem_bond]

hbguan@163.net (blue sky) wrote in message news:<f1e4b2b2.0404101825.326617cf@posting.google.com>...

The board have a 3.3v refence voltage. Another input voltage can
change from 1.5V to 5.5V, but need to clip to 3.3v.
Vout =Vin (Vin <3.3V)
Vout =3.3v (VIN >=3.3V)
If I want to use Infineon's switching transistor (SMBT3904/SMBT3906),
how to design it? I know its a simple question, I'm just a beginer in
hardware design.
Any tips is welcome.

Use resistor and zender diode

Vin Vout
-------/\/\/\/---------
|
|
__
/\ 3.3v Zender diode
--
|
|
-----------------------