The LX1692 is a microcontroller-family power-management/charger/PMIC (context depends on the exact part variant). Many LX-series chips include a dedicated "PROTECTION" or "PROT" pin used to signal, enable, or latch protection states (overcurrent, overtemperature, short-circuit, battery fault, etc.). The exact behavior of the protection pin varies by manufacturer and specific LX1692 datasheet revision; below are general behaviors, common use patterns, and recommended design practices.
The most fascinating aspect of the LX1692 protection circuit is its windowed sensitivity.
The chip does not simply trigger a fault if the pin sees ground. In many configurations, the protection circuit monitors the voltage level on this pin relative to specific thresholds (often around 1V to 3V logic levels depending on the application circuit).
Here is the interesting engineering nuance:
Once that threshold is breached, the LX1692 enters a Latched Fault Mode. It shuts down the PWM drivers instantly, saving the MOSFETs from exploding and the transformers from burning out. It is a digital "panic button" that requires a full power cycle to reset, forcing the user to acknowledge the hardware failure. lx1692 protection pin
A: You can, but it is unsafe. It should only be done as a temporary test or on a device you are willing to risk destroying. For a permanent fix, replace the faulty component causing the trigger.
When implementing the LX1692 in a system, designers need to carefully consider the protection features to ensure reliable operation. This includes:
If one of the backlight tubes is cracked or its solder joints have failed, the transformer sees an infinite impedance. The voltage skyrockets, the over-voltage protection (OVP) circuit triggers, and the protection pin is pulled high. Fix: Replace the CCFL tube.
Before we focus on the pin itself, let us establish context. The LX1692 is a high-efficiency, current-fed push-pull inverter controller. Its primary job is to convert a DC voltage (typically 5V to 24V) into a high-frequency AC waveform to drive CCFL tubes. These tubes provide the backlight for older LCD monitors, TVs, and laptops. The most fascinating aspect of the LX1692 protection
The chip includes several safety features, including over-voltage protection (OVP), over-current protection (OCP), and open-lamp protection. All of these safety signals feed into a single, master control pin known as the Protection Pin.
The LX1692 protection pin and its associated protection features are critical for the reliable operation of LED backlighting systems. By understanding these features and properly designing and testing their implementation, manufacturers can ensure that their products are robust, reliable, and capable of withstanding various electrical stresses. This not only enhances the lifespan of the product but also reduces the risk of damage and the need for costly repairs or replacements. As technology continues to evolve, the integration of sophisticated protection mechanisms in ICs like the LX1692 will remain a cornerstone of design for reliability and performance in LED lighting and backlighting applications.
is a Direct Drive CCFL (Cold Cathode Fluorescent Lamp) controller typically found in LCD TV backlight inverters. In repair and troubleshooting, technicians often focus on the "protection pin" to bypass the integrated safety features that shut down the backlight when a fault—such as an open lamp or short circuit—is detected. Key Details on the LX1692 Protection Pin
: The IC includes safety circuits that monitor the transformer secondary voltage. If a lamp fails or the voltage spikes, the protection circuit triggers a shutdown to prevent damage. Protection Pin Number : For the LX1692, the Once that threshold is breached, the LX1692 enters
pin (often Pin 1 or Pin 14 depending on the specific board layout and IC package) is frequently used to manage or bypass protection. Bypassing for Diagnostics
: Technicians sometimes bypass this pin to force the backlight on to determine if the issue lies with the lamps or the controller itself. : A common bypass method involves connecting a (typically between 10kΩ and 47kΩ ) between the protection pin and ground. Summary of Safety Features The LX1692's protection logic is designed to guard against: Open Lamp Faults : When a CCFL bulb is disconnected or broken. Short-Circuit Faults : Prevents fire hazards from electrical shorts. Over-Voltage
: Limits the transformer's secondary voltage to protect components. [!WARNING] Safety Risk : Bypassing protection is for diagnostic purposes only
. Operating a faulty backlight system permanently with the protection disabled can lead to transformer failure, fire, or electric shock. Always replace the faulty lamp or component after testing. or a step-by-step bypass guide for a particular TV model? lx1692 PDF | PDF | Electronic Circuits | Capacitor - Scribd
Professional rule: Only bypass the protection pin to confirm that no other major faults exist (like a shorted MOSFET). If the backlight stays on after bypassing but looks normal, you likely have a false trigger from a leaky capacitor, not a real fault.