What are the DIR pin and /OE pin on a level shifter IC?

The DIR pin determines the communication direction of the input/output pins, and the /OE pin controls whether the level shifter's output is enabled or disabled.

The “DIR pin” on bidirectional level shifters stands for Direction and determines the communication direction. Setting DIR to a high level enables communication from pin A to pin B, while setting it to a low level enables communication from pin B to pin A. This pin allows you to determine the signal communication direction.
The “/OE pin” stands for Output Enable and controls the on/off state of the output pins. The “/OE” pin with a slash (bar) enables communication at the L level and becomes an input impedance at the H level. The “OE” pin without a slash (bar) behaves in the opposite manner.
When multiple ICs are connected to the same signal line, a bus conflict (collision) may occur. In this case, controlling the output via the OE pin allows enabling the output only when necessary, while setting other ICs to Hi-Z prevents collisions.

Multiple outputs from a general-purpose CMOS logic IC come into conflict (Short-circuiting)

Table-１：DIR,/OE Pin Description
Terminal Explanation State Action
DIR Determine the data communication direction 1 (High) A → B
0 (Low) B → A
/OE Determine output ON/OFF 0 (Low) Output enabled (ON)
1 (High) Output disabled (OFF)

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