SCES692D June 2008 – February 2016 SN74AVC2T245
PRODUCTION DATA.
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
The SN74AVC2T45 is used to shift IO voltage levels from one voltage domain to another. Bus A and bus B have independent power supplies, and a direction pin is used to control the direction of data flow. Unused data ports must not be floating; tie the unused port input and output to ground directly.
Calculate the enable times for the SN74AVC16T45 using the following formulas:
In a bidirectional application, these enable times provide the maximum delay from the time the DIR bit is switched until an output is expected. For example, if the SN74AVC2T245 initially is transmitting from A to B, then the DIR bit is switched; the B port of the device must be disabled before presenting it with an input. After the B port has been disabled, an input signal applied to it appears on the corresponding A port after the specified propagation delay.
This device uses drivers which are enabled depending on the state of the DIR pin. The designer must know the intended flow of data and take care not to violate any of the high or low logic levels. Unused data inputs must not be floating, as this can cause excessive internal leakage on the input CMOS structure. Tie any unused input and output ports directly to ground.
For this design example, use the parameters listed in Table 2.
DESIGN PARAMETER | EXAMPLE VALUE |
---|---|
Input voltage range | 1.2 V to 3.6 V |
Output voltage range | 1.2 V to 3.6 V |
To begin the design process, determine the following:
Use the supply voltage of the device that is driving the SN74AVC2T245 device to determine the input voltage range. For a valid logic high the value must exceed the VIH of the input port. For a valid logic low the value must be less than the VIL of the input port.
Use the supply voltage of the device that the SN74AVC2T245 device is driving to determine the output voltage range.