Damn datasheet errors hit me again. A chip claims to output LVTTL level output for a received signal, but in reality the signal output AC level is same as received signal, riding on a VCC/2 bias.
So I need to convert a 200mV-600mV AC signal, riding on a 1.65VDC bias (or independent of that), to 3.3V LVTTL. Signal is around 3Mbps biphase, or in other words, very much like SPDIF. Source impedance unknown.
1) use RS422/RS485 receiver, good for 10MBps but most are 5V chips. Proper solution but expensive? Any 3.3V chips you could suggest?
2) use a hack with 74HCU04 or 74HC04 as linear amplifier. Hack but cheap, what if no signal is input, will it fry the chip as current flows through the input FETs as Vin=Vout? Which one? HC1G chips? Should I put a schmitt trigger after HC/HCU? Separate HCU04 and HC14, or single LVC1GX04 which contains both? Oh wait it has only buffers, not schmitt trigger?
3) Comparator? Too many extra components?