voltage level converter for MCUs

[Noman Yousaf]

hi all,
i want to control a shift rgister whish is CMOS(4015 or 4094).the circuit is supplied
12 volt.
i want to give the data and clock by AT89C51 MCU. That works on 5 volts.
how can i interface both circuits.i can not reduce the voltage of shift register circuit . i think i have to use voltage level converter which can convert 5volts logic level to 12 volt logic level.
please tell me about this

 

[silvio]

Use CD4504 https://focus.ti.com/lit/ds/symlink/cd4504b.pdf (SELECT input to HIGH).
If you have only two lines, then you can use NPN transistors and change the phase according with required edge.

 

[Noman Yousaf]

thanks for this link
i used transistors (as common emmitor mode)but beacuase of saturation of level, these did'nt work on hi speed.
is there any circuit of level converte which has op-amp or somthing? may be 4504 is not available in our country

 

[IanP]

Here is a circuit which converts from 3V to 5V logic ..
If you would like to convert level from 5V to 12V the suggested resistor values would be around 2kΩ ..
Regards,
IanP

 

[mwmmboy]

A good solution can be to use a digital optpcoupler with open collector.

Bye