An I/O standard with a single-ended signal, input/output (V_CCIO) voltages of 1.5 V, an input buffer of 1.5 V and an output buffer of 3.3-V/2.5-V TTL. The 1.5-V I/O standard is supported by the APEX^™ II, Stratix^™, and Stratix^™ GX device families.