Input signals can be up translated using the SN54SC8T138-SEP. The voltage applied at V_CC will determine the output voltage and the input thresholds as described in the Recommended Operating Conditions and Electrical Characteristics tables. When connected to a high-impedance input, the output voltage will be approximately V_CC in the HIGH state, and 0V in the LOW state.

The inputs have reduced thresholds that allow for input HIGH state levels which are much lower than standard values. For example, standard CMOS inputs for a device operating at a 5-V supply will have a V_IH(MIN) of 3.5 V. For the SN54SC8T138-SEP, V_IH(MIN) with a 5-V supply is only 2 V, which would allow for up-translation from a typical 2.5-V to 5-V signals.

As shown in Figure 7-2, ensure that the input signals in the HIGH state are above V_IH(MIN) and input signals in the LOW state are lower than V_IL(MAX).

Up Translation Combinations are as follows:

• 1.8-V V_CC – Inputs from 1.2 V
• 2.5-V V_CC – Inputs from 1.8 V
• 3.3-V V_CC – Inputs from 1.8 V and 2.5 V
• 5.0-V V_CC – Inputs from 2.5 V and 3.3 V

Figure 7-2 SCxT Up and Down Translation Example