ST2329B datasheet(8/23 Pages) STMICROELECTRONICS

8 / 23 page

Supplementary notes

ST2329B

8/23

DocID023359 Rev 3

Supplementary notes

4.1

Driver requirements

The ST2329BQTR may be driven by an open drain or totem pole driver and the nature of

the device output is “open drain”. It must not be used to drive a pull-down resistor as the

impedance of the output at HIGH state depends on the pull-up resistor placed at the I/Os.

As the device has pull-up resistors on both the I/OVCC and I/OVL ports, the user needs to

ensure that the driver is able to sink the required amount of current. For example, if the

settings are VCC =5.5 V, VL = 4.3 V, and the pull-up resistor is 10 k, then the driver must

be able to sink at least (5.5 V / 10 k

) + (4.3 V / 10 k)

 1 mA and still meet the V

requirements of the ST2329BQTR.

4.2

Load driving capability

To support the open drain system, the one-shot transistor is turned on only during high

transition at the output side. When it drives a high state, after the one-shot transistor is

turned off, only the pull-up resistor is able to maintain the state. In this case, the resistive

load is not recommended.

4.3

Power-off feature

In some applications where it may be required to turn off one of the power supplies

powering up the level translator, the user can turn off the VCC only when the OE pin is low

(device is disabled). There is no current consumption in VL due to floating gates or other

causes, and the I/Os are in a high-impedance state in this mode.

4.4

Truth table

Table 3. Truth table

Enable

Bi-directional input/output

I/OVCC

I/OVL

H(1)

1. High level VL power supply referred.

H(2)

2. High level VCC power supply referred.

H(1)

Z(3)

3. Z = high-impedance.

Z(3)

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