ST2129B Datasheet, PDF (8/21 Pages) STMicroelectronics – 2-bit dual supply level translator without direction control pin, push-pull output

Supplementary notes
3
Supplementary notes
ST2129B
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
source/sink maximum current of (V_CC/4) mA to/from the weak 4 k output buffer.
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
Enable
Table 3. Truth table
Bi-directional input/output
OE
H⁽¹⁾
H⁽¹⁾
L
1. High level V_L power supply referred.
2. High level V_CC power supply referred.
3. Z = high impedance.
I/O_VCC
H⁽²⁾
L
Z⁽³⁾
I/O_VL
H⁽¹⁾
L
Z⁽³⁾
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