Determining LCM and OVD Thresholds for the DS3xxx CCFL Controllers

By: Shoumin Liu

Abstract: The DS3881, DS3882, DS3988, DS3991, DS3992, and DS3994 are CCFL (cold-cathode fluorescent lamp)controllers that backlight LCDs (liquid crystal displays). Each controller channel has two input pins for lamp monitoring and current regulation, LCM and OVD. There are four thresholds associated with these two inputs. This application note describes how the thresholds are specified and how to determine correct threshold values based on the application.