SN74LVC1G08-Q1: Y output current limit

Meng Liu

Intellectual 1765 points

Part Number: SN74LVC1G08-Q1

Hi Expert

My customer use case as below：

pin1 always =5V（Pin1 connect to VCC）

Pin 2 normally is float and triggered low voltage when system fault.

Y connect 3.3V voltage that normally current is limit 100mA.

when Pin2 tie to low, Y will sink current and output low

question:

when they doesn't set the 3.3V output current limit and pin2 tie to low， the output voltage will keep 3.3V and the sink current is 180mA. customer want to know: why device can sink 180mA, which part need this huge current in internal of device?

over 1 year ago

0 Owen Westfall over 1 year ago

TI__Expert 4531 points

Hi Meng,

Please see [FAQ] How does a slow or floating input affect a CMOS device?

Leaving an input floating can be very bad and cause damage to the device, so we highly recommend this second input to be tied either high or low at all times.

Regards,

Owen

0 Clemens Ladisch over 1 year ago

Guru 243220 points

The output is not designed to be shorted to a power supply.

Section 9.2.2 of the datasheet says:

Load currents should not exceed (I_O max) per output and should not exceed total current (continuous current through V_CC or GND) for the part. These limits are located in the Absolute Maximum Ratings table.

Exceeding the absolute maximum rating is likely to damage the device.

The SN74LVC1G08-Q1 cannot be used in this way. What is the actual problem you're trying to solve?

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SN74LVC1G08-Q1: Y output current limit