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By osegouin
#198440
For a projet with "BIG LCD", I need to connect mofset on an Sparkfun Large Digit Driver card
How do you add mofset on output for drive big power ? I'll try with STP16NF06 but it's does'nt work :cry:
Have you a shematic ? Thanks,
Oliver
By paulvha
#198461
The TPIC6C596 on the board has active output to GND (drain). The mosfet needs active HIGH on the GATE to open up. It will not work if you connect it directly. The logic has to be inverted.

Method A : The best & safest way is to use an optocoupler for each channel. The output of each board channel will pull to ground and the optocoupler led (with a serial resistor R1 ohm to the +5V), will lid up. The optocoupler-receiver will conduct and sent a +5v voltage to the gate of the mosfet. That same gate has a 10K pull down resistor connected to ground. The R1 can be calculated with help of internet sites (about 220 ohm)

Method B: The output of each board channel is connected to the gate of the mosfet. That same gate has a pull-up resistor of 10K to +5V. What you need to do is change the sketch so that every channel (a - f) that needs to lid up should NOT get a value of 1 written, but 0, and all the others that should NOT lid up, get a 1.

Paul