I'm using the VNQ9080 in a design and am undecided about adding pull-downs to the inputs. The inputs are controlled from a SX1509 I2C I/O expander which has the pins on HI-Z by default. I want to make sure that the VNQ9080's outputs are off by default. Is it necessary to add pull-downs to the inputs of the VNQ and on which side of the Rprot would i place them?
1 Answer
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In the VNQ9080AJ datasheet there's a suggestion table for unused and unconnected pins:
So the inputs can be left floating if not used.
After a reset of the I/O expander, the I/O directions change to input, and all pull-down/-up resistors are disabled (See the register tables in the datasheet). So the I/Os, therefore the VNQ9080's inputs, can be considered as "floating" until the I/O expander is configured.
Because the high-side driver allows inputs to be floating, you don't necessarily need to use any pull-down resistors. Because otherwise would already be stated as "Not allowed" in the table above.
