Electronics > Projects, Designs, and Technical Stuff
MAX 7000S driving 5V Logic
(1/1)
NivagSwerdna:
In the context of 1980s Arcade game PCBs...
I'm contemplating having a go at replacing some custom logic with a MAX 7000S device which appears to be pretty cheap on ebay (despite being obsolete). If I drive the device at 5V I see that in order to drive 5V CMOS outputs that an external pull-up resistor is required, I even found an application note: http://extras.springer.com/2001/978-3-662-04615-9/an/an107.pdf
How am I meant to calculate RExt? 10k 47k?
EPM7128SLC84-15 is the device of choice.
Thanks in advance,
edgaras006:
From load capacitance and required switching frequency. Since it uses only nMOS logic, for +5V output you need a pull up resistor. R = 1/(2*pi*Cload * F switching). On the other hand, RC should be approximately 1/10 of switching frequency. Side note if you reduce R too much you might hit n most current limit, so watch out for that.
Navigation
[0] Message Index
Go to full version