The LX1692 is a high-efficiency, full-bridge inverter controller designed for CCFL (Cold Cathode Fluorescent Lamp) backlighting in LCD displays. To ensure safe operation and prevent damage from fault conditions, the IC integrates multiple protection features managed through a dedicated (often labeled as OVP or CP in datasheets).
Connect a 100kΩ resistor from the protection pin to a 3.3V or 5V standby rail to "fool" the IC into thinking current is always present. Method B (Disable by Grounding): Short the protection pin directly to ground via a 10Ω resistor. lx1692 protection pin
Voltage on the protection pin stays within a predefined window (e.g., 0.8V to 1.2V). The IC continues generating the 40kHz–80kHz drive signal for the MOSFETs. Method B (Disable by Grounding): Short the protection
The LX1692 includes several integrated safety mechanisms designed to protect the inverter and lamps: Open Lamp Voltage Protection: The LX1692 is a high-efficiency
: The LX1692 can detect electrical arcing if the level is high enough to trigger internal thresholds. Technical Specifications for Protection Threshold (Typical) Open Lamp Detection Enable Over-Voltage Threshold Over-Current Threshold ISNS Strike Threshold Troubleshooting and Disabling Protection
Prevents excessive secondary voltage when a lamp is disconnected or fails to strike.
Before analyzing the protection pin, we must understand the host chip. The LX1692 is a high-efficiency, current-mode PWM controller IC designed specifically for CCFL (Cold Cathode Fluorescent Lamp) backlight inverters. You will find it on inverter boards for Dell, HP, Lenovo, and Acer monitors, as well as many laptop screens from the mid-2000s to early 2010s.