5 volt compatible inputs, SN65LVDS391D Quad LVDS Driver with 5 volt tolerant inputs

Kenneth Aquino

Other Parts Discussed in Thread: SN65LVDS391

The SN65LVDS391D has 5 volt tolerant inputs. I plan on driving each input with a 5 volt logic signal and the SN65LVDS391D supply voltage will be 3.3 volts.. I am not familiar with the input structure of the SN65LVDS391D. If I have no series resistor between each SN65LVDS391D input and the 5 volt device driving that input, what will the current be?

Also, without the above-mentioned series resistor to limit the current into the SN65LVDS391D input, is it possible that the SN65LVDS391D will go into SCR-latchup if the 5 volt device is powered-up before the SN65LVDS391D's 3.3 volt supply is powered up?

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 317110 points

There is no noticeable input current, even without a series resistor. See [FAQ] Can the input voltage (Vi) to my logic device be higher than the supply voltage (Vcc)?

0 Kenneth Aquino over 3 years ago in reply to Clemens Ladisch

Expert 1330 points

What about the case where the 5 volt device is powered off and its inputs are being driven by the 3.3 volt device. I did not see anything in the SN65LVDS391D data sheet mentioning the "Ioff - Partial Power Down Protection" feature mentioned in the FAQ that you linked.

0 Clemens Ladisch over 3 years ago in reply to Kenneth Aquino

Guru 317110 points

Overvoltage-tolerant inputs have a high impedance even when the device is powered off. In the SN65LVDS391 datasheet, this is implied only by the absolute maximum ratings, which allow V_CC = 0 V.

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5 volt compatible inputs, SN65LVDS391D Quad LVDS Driver with 5 volt tolerant inputs