SN74LVC1G17: Clarification on datasheet maximum input voltage range

Kiran Kerai

Part Number: SN74LVC1G17

The datasheet for this part states "The input and output negative-voltage ratings may be exceeded if the input and output current ratings are observed."

This implies that as long as the input current is not <-50mA, negative voltage rating can be exceeded.

If this is incorrect, please confirm the maximum negative voltage that can be applied.

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 317370 points

There is an ESD protection diode from GND to the pin; if the voltage at the pin becomes too low (at about −0.5 V), current flows through the diode out of the pin and thus clamps the voltage. If that current becomes too high, the diode (possibly together with other nearby components) will burn up.

The actual voltage at the pin depends on the voltage drop over the diode. It will become higher with higher currents, but it will not be very much higher at the 50 mA limit. Therefore, it is possible to exceed the −0.5 V limit, but not by very much.
(An ESD event typically has thousands of volts, which results in a much larger current, but only for a very short time, so it would not result in a dangerous temperature increase.)

0 Kiran Kerai over 8 years ago in reply to Clemens Ladisch

Intellectual 380 points

Thanks for your response.

Voltage is applied to this device through a resistor. In this case, if the current is limited to <50mA I expect the diode will clamp the voltage above -0.5V and there will be no damage?

Please confirm.

0 Clemens Ladisch over 8 years ago in reply to Kiran Kerai

Guru 317370 points

Yes, a resistor is sufficient to limit the current.

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SN74LVC1G17: Clarification on datasheet maximum input voltage range