High Drive mode downsides (nRF52)

[Gordon]

Hi,

I just had a quick question - currently I'm using standard drive mode for everything, however in one case I'm driving an IR transmitter that could really do with a little more current.

What are the downsides of using high drive mode? I can imagine it uses more power when the pin is changing state, but does it use more power all the time?

Since I'm making a general purpose device, it seems like perhaps I should use high drive mode by default on all pins, but I'm wondering if there are any problems with that?

thanks!

[Jørn]

Hello Gordon

Please see the following links for more information on the current limitations of the nRF52 devzone.nordicsemi.com/.../

devzone.nordicsemi.com/.../

devzone.nordicsemi.com/.../

To summarize we do not recommend going over 15 mA source/sink on all gpios combined, and it is better to sink than source due to a higher number of ground pads.

In addition to this using high drive may demand a higher VDD than low drive (see GPIO electrical specifications in the product specification). As you suspect it will increase the power consumption, but our measurements indicate it will not affect consumption during switching, only if you’re actively sourcing something which draws a lot of current.

Edit: Another point worth mentioning is the recommendations for usage of GPIO pins near the radio power supply and antenna pins. See section 4.3 in the product specifications.

Best regards

Jørn Frøysa

[Gordon]

Great, thanks! I'm not likely to go over that. So realistically as long as I keep well within the current limit for the given voltage, there's no real problem with just using all my IOs in high drive mode.

[ctchong]

For current sinking of high drive do I use the mode 

NRF_GPIO_PIN_H0H1 = GPIO_PIN_CNF_DRIVE_H0H1, ///< !< High drive '0', high-drive '1'.

or 

NRF_GPIO_PIN_H0D1 = GPIO_PIN_CNF_DRIVE_H0D1, ///< !< High-drive '0', disconnect '1'.

Thank you 

Best regards,

Chong