High drive

[Andrew Mowry]

I'm considering using the NRF52840 for a device with infrared proximity sensors that requires 8 IR LEDs to be driven at around 14 mA successively (never more than one at a time). Would I be okay sinking current with 8 pins set to high drive, or would I need a dedicated LED driver IC for this? I'll also be using BLE, USB, and SPI or I2C. Thanks!

[ketiljo]

14 mA should be ok as long as you don't drive any other load at the same time. One GPIO can sink or source ~5 mA, but more if the voltage can be lower. If you use only one GPIO pr. LED, you will need a smaller series resistor to compensate for the internal resistance in the GPIO. You can parallel more GPIOs to increase the drive strength. 

[hmolesworth]

14mA in high-drive is fine as ketiljo mentions, however be aware that v1.7 nRF52832 Product Specification has this note (which seems a little over-pessimistic):

"To ensure optimal performance, it is not recommended to sink/source more than 15 mA combined from the
GPIO pins"