Voltage conversion 3.3v -> 24v

Altera_Forum · ‎09-01-2011

Hello all,

I have a DE-2 board and I am looking to control a few PLCs. I need to take the 3.3v and convert it to 24v, as well as, take 24v and convert it to 3.3v. The DE-2 Board is acting like a divide by circuit. It takes an encoder signal at 24v (max 100kHz) as the clock and divides it down to produce a trigger. The divisible number is supplied via the 24v to 3.3v as a 16 bit value. (4 bits sent at a time)

Going from 24v to 3.3v I believe I can just do a divide by circuit for the encoder but the 3.3v to 24v seems to be tricky at speeds greater than 5kHz.

I have found so far:

3.3v->5v 74HCT244

5v->24v ?

Thanks

Altera_Forum · ‎09-01-2011

These work nicely for switching higher voltages from FPGA IOs:

http://www.irf.com/product-info/datasheets/data/pvg612.pdf

but they're a little slow for your needs.

Have you though of using a power supply MOSFET driver?

For example, look at page 25 of this schematic:

http://www.ovro.caltech.edu/~dwh/carma_board/gda06rb004_carma_v0.87_dec03.pdf

The Texas Instruments UCC27223 are logic-level input MOSFET drivers. You could use that component, or something similar, to switch 24V pretty rapidly, you'd just need to use MOSFETs with the right voltage rating.

Cheers,

Dave

Altera_Forum · ‎09-01-2011

Most gate driver IC (also UCC27223) are limited to 18 or 20 V supply voltage. For lower current and higher output voltage, you can either use special interface drivers, or e.g. fast operational amplifiers/comparators.