: Features a simplified protection loop consisting of localized Over-Current Protection (utilizing Hiccup mode) and thermal shutdown safeguards.
: Current sink inputs for each LED backlight string. Pin 12 (COMP) : Error amplifier output for compensation.
: It is typically connected to a resistor divider from the output voltage.
Forces a recoverable shutdown if the internal junction temperature exceeds safety thresholds. Pin Layout and Hardware Implementation
: Includes recoverable thermal shutdown, meaning the device will restart once it cools to a safe operating temperature. External Control MP3378E datasheet mp3378e protection pin upd
: If an LED string is open or shorted, avoid replacing a single diode. The remaining aged diodes will soon experience over-current stress and fail. Replace all internal strips with new, high-quality replacements.
These pins monitor the current and residual voltage across each LED string. If a channel drops to near-zero volts (LED shorted) or spikes abnormally (LED open), the IC identifies an imbalance and cuts power to protect the panel from uneven thermal dissipation. Step-by-Step Diagnostic and Modification Guide (UPD)
Some designs allow the host controller to read the PROT pin via an ADC. If UPD is persistent but the backlight is functional at reduced brightness, implement:
Sets the step-up converter's switching frequency via an external resistor to ground. : Features a simplified protection loop consisting of
Monitors individual channel voltages. A shorted or completely open LED string skews the expected voltage, forcing the IC into latch protection. Current Sense Feedback
RDS(ON)cap R sub cap D cap S open paren cap O cap N close paren end-sub
: Provides a step-down internal bus or standby power rail via internal low
Connects to an external resistor divider from the output to ground; if the sampled voltage exceeds the internal latch threshold, it stops the switching cycle. Enable & Loop Compensation : It is typically connected to a resistor
The MP3378E relies on integrated safety feedback loops to protect both the internal chip architecture and external display components.
Perhaps the most critical aspect of the update is the move toward Single String Protection (SSP) . In older designs, if one LED string out of four failed (opened), the protection pin would often shut down the entire backlight. The updated logic allows the driver to identify the specific failing string, disconnect it electrically, and allow the remaining strings to function. This is a profound philosophical shift. It accepts that components fail, but prioritizes system continuity. The protection pin has evolved from a kill switch into a traffic controller, rerouting safety around the accident.
It allows designers to set a specific protection threshold, ensuring the output capacitor and MOSFET are never exposed to voltages exceeding their ratings. 2. Advanced LED String Safeguards