Development Tools/Demo Boards - EVB LAN9252 - Noisy Interrupt Pin Input Signal

Is a pull-down/up resistor necessary on pin 72 of U7 (incoming IRQ) of the LAN9252-HBI&SPI+GPIO-EVB evaluation board? The signal measured seems to be a bit noisy.

Interrupt request (IRQ) signal testing was done on the EVB-LAN9252 HBI evaluation board and the signal received is as expected without adding any external pull-down resistor. The IRQ is configured as push-pull, active low output. If the IRQ pin is configured as push-pull, it means the IRQ output will be driven high or driven low. No external pull-up/pull-down is needed for active high or active low output.

However, if the IRQ pin is programmed as open-drain output, the interrupt is active low and will be driven low by the chip. When the interrupt is inactive, the chip does not drive the IRQ pin and usually, an external pull-up (typically 1 KΩ or 4.7 KΩ) to the same I/O supply as the IRQ pin is needed.

This may occur if you configured the IRQ pin as open-drain output and/or there is some capacitive loading on the pin that is skewing the signal.

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