Logitech K380 Faq page 23

NOTE:
and that the OS X Bluetooth Setup Assistant will launch if a Bluetooth
keyboard, mouse or trackpad is not detected as connected to your Mac.
4. Click OK.
 +Connect the K380 keyboard to an iPad or iPhone
You can connect your keyboard to an iPad or iPhone running iOS 5.0 or later. Here's how:
1. With your iPad or iPhone turned on, tap the Settings icon.
2. In Settings, tap General and then Bluetooth.
These options ensure that Bluetooth-enabled devices can wake your Mac,