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Topic: Driving 12V signal from 5V pin (Read 3 times) previous topic - next topic

pwillard


captncraig

I am attempting to make a shield to program my 64KB eeprom module (27SF512- datasheet at http://www.moates.net/zips/27SF512.pdf). I am using three 74HC595 chips to shift out the 16 bit address and the 8 data bits. All of the logic is fine at 5V, except part of the programming protocol requires me to set several pins on the eeprom to 12V.

I need to somehow convert the 5V signal from the arduino to a 12V signal to give the eeprom. I am pretty sure I can do this with a single transistor, but my circuit skills are a bit weak and I'm afraid I'm not sure how to connect it, which model I should use, or what kinds of resistors I will need.

Additionally, one of the address pins needs to be given 12V to initialize an erase operation. That pin is also connected to an output from one of my 595s. Do I need a diode or something to protect that pin from getting fried? Will that be enough, or do I need a more complicated circuit to ensure its not getting 5V and 12V at the same time? Not sure what will happen in that case.

I've attached my circuit as it stands now in eagle. The OE pin is not attatched to anything, and the A9 pin is only connected to the 595, not to the other 12V line that needs to be put in there. We can assume Vin will be a 12V supply, so that is easily accessible. Any tips would be greatly appreciated.

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