Canon L90 - Manual (Page 47)

Before Using the Machine
1-16
4
Press [ ] or [ ] to select <ON>, then press [OK].
5
Press [ ] or [ ] to select the desired interval, then press [OK].
You can set the interval from 3 to 30 minutes (in one-minute increments).
You can also enter values using numeric keys.
The default setting is 5 minutes.