Low-Voltage TTL (LVTTL)

LVTTL is a general-purpose standard (EIA/JESD8-B) for 3.3 V applications. It uses an LVTTL input buffer and a push-pull output buffer. GPIO supports the LVTTL I/O standards, and the LVTTL output buffer can have up to six different programmable drive strengths. For more information about programmable drive strength control, see Table 1.