74LVC_LVCH2T45

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Product data sheet

Rev. 4 — 20 August 2010

23 of 36

NXP Semiconductors

74LVC2T45; 74LVCH2T45

Dual supply translating transceiver; 3-state

14. Application information

14.1 Unidirectional logic level-shifting application

The circuit given in Figure 16 is an example of the 74LVC2T45; 74LVCH2T45 being used

in an unidirectional logic level-shifting application.

14.2 Bidirectional logic level-shifting application

Figure 17 shows the 74LVC2T45; 74LVCH2T45 being used in a bidirectional logic

level-shifting application. Since the device does not have an output enable pin, the system

designer should take precautions to avoid bus contention between system-1 and

system-2 when changing directions.

Fig 16. Unidirectional logic level-shifting application

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system-1

1A

2A

GND

1

2

3

4

8

7

6

5

1B

2B

DIR

74LVC2T45

74LVCH2T45

system-2

Table 16.

Description of unidirectional logic level-shifting application

Pin

Name

Function

Description

supply voltage of system-1 (1.2 V to 5.5 V)

2

1A

OUT

3

2A

OUT

4GND

GND

device GND

5

DIR

DIR

the GND (LOW level) determines B port to A port direction

6

2B

IN

7

1B

IN

supply voltage of system-2 (1.2 V to 5.5 V)