Denzel Johnson added 13 points and Brandon Clark and Jarvis Pugh had 10 apiece as Santa Clara (12-16, 6-10 West Coast) nearly blew a 17-point lead but went 5 of 6 from the line over the final 36 seconds to clinch the win.
The Broncos opened with a 19-5 run that included four of Brownridge's 3-pointers and carried a 35-21 advantage into the break.
Loyola Marymount steadily chipped away in the second half, using an 8-0 burst in the final minute that included a 3-pointer from Matt Hayes and five points from Godwin Okonji to cut it to 65-63 with 50 seconds to play. The Lions missed their final three shots.
Hayes led LMU with 20 points, David Humphries added 16 and Okonji 15.