Welcome to the site. You really have not given us much to go on, more information will be helpful. For starters please put your general location in your profile. Additional information would be:
1. How long have you had this tree and is this a new development?
2. Has it been re-potted recently?
3. What is the condition of the soil and roots?
4. With what, and how often, are you fertilizing?
5. Is your water high in mineral content, particularly salt?
6. What have temperatures been like in your area recently?
7. How are you handling your watering?
I don't have a Trident but have struggled with leaf burn on Acer palmatum in the past. Tender, new foliage seems to be especially susceptible. If your plant is not in good overall health it may not be taking up enough water to keep up with losses through transpiration. High levels of salts in your soil may also be a problem.