Hi Chico,



As Richard already mentioned, it's not wise to drive loads with the reset level of micro. There are situations, where the reset supervisory chip can keep the micro resetted for a long time. Would you like all your loads including two heavy laser modules staying uncontrolledly turned on for a long time? Believe me, that's no good idea.

Another issue is the input capacitance of MOSFET. If you omit the 74HCMOS driver, you would need two resistors, one pull-up to turn the MOSFET reliably on and one to limit the discharging current of gate source capacitance into the micro when it tries to turn the MOSFET off. Without a current limiting a huge ground bounce would be the result, eventually stopping the micro from running properly. The resulting scheme with two resistors in combination with a standard quasi-bidirectional port line has other disadvantages. So, if you really want to drive the MOSFET with a logic high, put two 74HC04 inverters in series.


Following the datasheet, Vgs of IRF630/640 is up to 4V (3V typically) for a source drain current of only 250µA. So, some of them might work, others not. Give it a try, but order a better one for your final product.

Eventually, you should add a free wheeling diode to your laser module. Depends on actual circuitry of laser module.

Kai Klaas