st2149 STMicroelectronics, st2149 Datasheet - Page 5

• Manufacturer Part Number: st2149
• Description: 4-bit Dual Supply Level Translator Without Direction Control Pin
• Manufacturer: STMicroelectronics

ST2149
3
3.1
3.2
3.3
3.4
Supplementary notes
Driver requirement
For proper operation, the driver from each side of the device must have capability to source
and sink a minimum of 1 mA current. The device architecture requires the driver to
source/sink maximum current of (V
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 4kΩ resistor will maintain the state. So, resistive load or
pull-up resistor less than 50kΩ is not recommended for proper operation.
Power off feature
In some application where it might be required to turn off one of the power supplies
powering up the level translator. The device will be automatically disabled when V
is turned OFF, even if the OE pin is set to HIGH (enabled). In this mode, all I/Os are in high
impedance state.
Truth table
Table 3.
1. High level V
2. High level V
3. Z = High impedance.
Enable
Truth table
L
CC
H
H
OE
power supply referred.
L
(1)
(1)
power supply referred.
Doc ID 15949 Rev 1
CC
/4) mA to/from the weak 4 kΩ output buffer.
I/O
H
Z
L
VCC
(3)
(2)
Bidirectional Input/Output
Supplementary notes
I/O
H
Z
L
(3)
(1)
VL
CC
supply
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