PS/2 keyboard power supply

[davorin]

Are todays PS/2 keyboards 3V3 tolerant or do all need still 5V supply?
Want to avoid using level translators just for one keyboard in FPGA project (o;

 

[barny451]

The keyboard connector will give you 5V. As in 5V full stop. Don't think this will ever change, just as the keyboard communication protocol hasn't changed since it was first introduced on the IBM PC/AT all those years ago...

The clock and data lines are open collector, so as long as you let the motherboard pull-ups do the work of pulling up to 5V, and tolerate 5V on your FPGA project inputs, you could drive them from 3.3v logic.

HTH
Barny

 

[arcaphill]

The PS/2 use 5V only. On motherboard, the PS/2 use 5V_Dual power, it means when the MB power off, the 5V standby will supply the PS/2 also!

 

[farhada]

Are todays PS/2 keyboards 3V3 tolerant or do all need still 5V supply?
Want to avoid using level translators just for one keyboard in FPGA project (o;

I did a similar project a few months ago, and used pullup resistors on all signals and it worked fine.

You must have +5V for the keyboard, so you already have the 5V available on your design (I assume), so putting a couple of 10k pullups will not hurt.

Good luck,
/Farhad