I need to know whether the nRF24L01(+) has an open-collector IRQ output, or a full push-pull driver. The datasheet doesn't mention this fact.
The reason is that I'm working on a circuit involving two peripherals (an nRF24L01 and another chip) attached to an MCU that has only a single INT pin. If both the devices have open-collector IRQ lines, I can easily just wire them all together with an overall pullup resistor, and all will work fine. If however, the nRF24L01 has a full push/pull driver on the IRQ line, then this is impossible, and instead I'll have to buffer it somehow (perhaps with a 7407 or similar). When the interrupt fires, I can query each device over SPI to enquire which device fired the interrupt.
Best Answer
The IRQ pin is a normal Push-Pull output.
There is a very good tutorial document available on the internet: nrf24l01_tutorial_0.pdf
In there it says this about the IRQ line:
It goes on to say:
Although it doesn't explicitly say it, the wording implies that it is a normal push-pull output, otherwise one would expect the author to make mention of it being open collector and a pull-up resistor being required.
Also, in the datasheet the pin is labelled as a "Digital Output". In the DC characteristics in section 5.6 it lists the output voltages for a "Digital output pin" (table 13). An open collector wouldn't have an output voltage, so it must be push-pull.