SN74LVC1G11: Input and output current limit

Vidhya Jeyapaul

Intellectual 780 points

Part Number: SN74LVC1G11

HI Team,

I am using SN74LVC1G11DBVR.

1.Input current limit per pin (A.B.C pins) is 5uA?

2. If the logic high input that I am driving is in mA, should I limit this current using a series resistor?

But IIK limit is 50mA.

3. Can this gate output be connected as a logic input to another gate?

Please clarify.

Thanks,

Vidhya

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 277390 points

CMOS devices have high-impedance inputs. If the input voltage is inside the limit specified in the recommended operating conditions, then no more than 5 µA will flow (and that is the worst case at the most extreme temperature). A series resistor is not necessary.

I_IK applies only if the input voltage goes below ground.

Inputs and outputs can be connected to other logic gates (running with the same supply voltage).

0 Vidhya Jeyapaul over 3 years ago in reply to Clemens Ladisch

Intellectual 780 points

Thanks Clemens.

Input to this gate is an output of an optocoupler whose collector current is 0.5mA in our design. SN74 will take 5uA max.

Any over loading limitation for the gates ? Please clarify.

Regards,

Vidhya

0 Emrys Maier over 3 years ago in reply to Vidhya Jeyapaul

TI__Guru* 96802 points

Hi Vidhya,

The input to the LVC family device is high impedance -- ie current will not flow into or out of the device in the normal operating voltage range (except for a very minor leakage, usually a few nanoamps).

5uA is the maximum possible leakage current under the worst possible conditions -- you won't ever actually see that.

If you can show me your circuit I might be able to comment further -- most likely there is no issue here.

0 Vidhya Jeyapaul over 3 years ago in reply to Emrys Maier

Intellectual 780 points

Hello Maier,

Refer to the snap below.

Please comment.

Thanks,

Vidhya

0 Emrys Maier over 3 years ago in reply to Vidhya Jeyapaul

TI__Guru* 96802 points

Hi Vidhya,

I don't see any problem with this circuit as shown (assuming B and C have valid signals also).

The output of the optocoupler will either pull the line low, drawing current through R62, or it will release the line, allowing R62 to pull it up to 3.3V. The input of U533 won't source or sink significant current.

0 Vidhya Jeyapaul over 3 years ago in reply to Emrys Maier

Intellectual 780 points

Thanks Maier.

Regards,

Vidhya

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SN74LVC1G11: Input and output current limit