* Question
What protection features are integrated into the UCC28600 controller?
* Answer
The UCC28600 from Texas Instruments is a high-performance flyback controller designed for efficient AC-DC power conversion. It integrates a comprehensive set of protection and fault-handling features to enhance system reliability and safeguard both the power stage and the connected load.
Below are the key protection mechanisms:
1. Overvoltage Protection (OVP)
The UCC28600 continuously monitors the auxiliary winding voltage to detect output overvoltage conditions. When the sensed voltage exceeds the predefined threshold, the controller immediately stops switching and enters a fault state. This prevents damage to downstream components caused by excessive output voltage during light-load or transient events.
2. Overcurrent Protection (OCP)
Cycle-by-cycle current limiting is implemented by sensing the primary current through the sense resistor. If the peak current exceeds the set limit, the device terminates the switching cycle instantly. This protects the MOSFET, transformer, and rectifier diode from overcurrent stress during startup or short-circuit conditions.
3. Overtemperature Protection (OTP)
The controller includes internal thermal shutdown circuitry. If the junction temperature rises beyond approximately 150°C, the device automatically disables switching and remains off until the temperature falls below the recovery threshold. This ensures robust protection under high ambient or overload situations.
4. VDD Undervoltage Lockout (UVLO)
The UCC28600 provides both turn-on and turn-off undervoltage lockout thresholds to guarantee stable operation. It prevents erratic switching during power-up or brownout conditions by ensuring the VDD supply is within the safe operating range before enabling the PWM drive.
5. Output Short-Circuit Protection
In the event of an output short circuit, the primary current quickly reaches the OCP limit. The controller detects repeated fault cycles and initiates hiccup-mode protection, periodically attempting to restart until the fault is cleared. This limits power dissipation and protects the converter against catastrophic failure.
Summary Insight
The UCC28600 combines multiple hardware-level protections with intelligent fault recovery mechanisms, making it ideal for energy-efficient and high-reliability offline flyback applications such as adapters, auxiliary power supplies, and industrial controls.
By integrating comprehensive protection at every stage—voltage, current, temperature, and startup—the UCC28600 ensures stable operation, extended system lifespan, and safe fault recovery, aligning with the stringent reliability standards required in modern power electronics.
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