[Arm-netbook] help needed with a ttl logic circuit

Luke Kenneth Casson Leighton lkcl at lkcl.net
Sun Aug 23 15:52:27 BST 2015


ok so i redid it, using a darlington pair, because yes the voltage
definitely needs to be below 0.69v at the output:  also, forget about
the "disconnected" operation, that can be done with a jumper.

http://hands.com/~lkcl/ttl_logic_circuit2.png

still don't feel completely happy (esp. with the schottky diode), i
feel another transistor might be needed especially because VREFTTL
(for the EOMA68_BOOT0 TTL level) could be *lower* than 3.3v.

l.



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