When both the driver and receiver are disabled (DE low and RE high) the device is in shutdown mode. If the enable inputs are in this state for less than 60 ns, the device does not enter shutdown mode. This guards against inadvertently entering shutdown mode during driver or receiver enabling. Only when the enable inputs are held in this state for 300 ns or more, the device is assured to be in shutdown mode. In this low-power shutdown mode, most internal circuitry is powered down, and the supply current is typically 1 nA. When either the driver or the receiver is re-enabled, the internal circuitry becomes active.

If only the driver is re-enabled (DE transitions to high) the driver outputs are driven according to the D input after the enable times given by t_PZH(SHDN) and t_PZL(SHDN) in the driver switching characteristics. If the D input is open when the driver is enabled, the driver outputs defaults to A high and B low, in accordance with the driver fail-safe feature.

If only the receiver is re-enabled (RE transitions to low) the receiver output is driven according to the state of the bus inputs (A and B) after the enable times given by t_PZH(SHDN) and t_PZL(SHDN) in the receiver switching characteristics. If there is no valid state on the bus the receiver responds as described in the fail-safe operation section.

If both the receiver and driver are re-enabled simultaneously, the receiver output is driven according to the state of the bus inputs (A and B) and the driver output is driven according to the D input.