TTL to CMOS converter | CMOS to TTL converter

This page describes TTL to CMOS converter and CMOS to TTL converter.

TTL to CMOS converter

TTL to CMOS converter

Figure-1 depicts simple TTL to CMOS converter. It converts TTL signal levels to CMOS signal levels. It is basically level converter. TTL levels are around 3V and CMOS levels are around 5V.

CMOS to TTL converter

CMOS to TTL converter IC

The CMOS to TTL converter does reverse of the above functionality. It converts CMOS signal levels to TTL signal levels. The same cable as mentioned above can be used with proper mating connectors.

Logic Type TTL CMOS
Logic 1 ( VIH ) 2 V 0.7* Vcc (equals 3.85V for Vcc = 5)
Logic 0 ( VIL ) 0.8 V 0.3*Vcc (equals 1.35V for Vcc=5)

TTL to CMOS converter and CMOS to TTL converters are useful for converting 3V system to 5V system and viceversa. Pls. note TTL is referred as 3V system and CMOS is referred as 5V system due to its use to logic levels near these supply voltages.

These converters normally use buffers at the input and output pins and level converter at the middle. It is also referred as voltage level shifter due to its functional operation. Refer TTL and CMOS interfacing concepts for more information.

The figure-2 depicts CMOS vs TTL converter. It houses total 6 number of inputs (AIN, BIN, CIN, DIN, EIN, FIN) and 6 number of outputs (AOUT, BOUT, COUT, DOUT, EOUT, FOUT) in addition to Vcc, Vdd and ground pins.

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