Supplementary notes

ST2129B

8/21

DocID023308 Rev 2

3

Supplementary notes

3.1

Driver requirement

For proper operation, the driver from each side of the device must have the capability to

source and sink a minimum of 1 mA current. The device architecture requires the driver to

3.2

Load driving capability

To support the architecture that allows level translation without direction pin, the one-shot

transistor is turned ON only during state transition at the output side. After the one-shot

transistor is turned OFF, only the 4 k

 resistor maintains the output logic state. So, 

a resistive load or pull-up resistor less than 50 k

 is not recommended for proper operation.

3.3

Truth table

Table 3. Truth table

Enable

Bi-directional input/output

OE

H(1)

H(1)

L

L

L

3. Z = high impedance.

Z(3)