Help with Texas Instruments SN74LVT125
From the datasheet for the TI SN74LVT125, the absolute maximum rating for signals applied to inputs are −0.5 V to 7 V. Generally, CMOS inputs are high impedance, so you would only expect microamps of input current, even with a +5V input. Since the datasheet says it operates with "5-V Input and Output Voltages With 3.3-V V_CC," I expect you can apply 5V directly to an input without any danger.