"Hiccup" overload protection in switching power supplies is a very common and effective protection method. It gets its name from the fact that it operates similarly to a human hiccup-cyclically switching on and off.
Next, I'll explain in detail how this protection method affects both the switching power supply itself and the customer's equipment.
What about the Working Principle?
When an overload or short circuit occurs at the output, the power supply's control circuit detects the anomaly and immediately shuts off the power switch (such as a MOSFET), ceasing power output. The control circuit then periodically attempts to restart (usually every few hundred milliseconds to several seconds). If the anomaly persists, it shuts down again, repeating this cycle until the fault is resolved.
A. Effect on the switching power supply itself (protecting the power supply)
1,Reducing thermal stress and preventing overheating damage:
This is the most critical function. If a power supply continues operating during a severe overload or short circuit, the enormous current will cause internal components such as the power switches, rectifier diodes, and transformers to generate extremely high heat, leading to a rapid temperature rise.
Burst mode provides these heat-generating components with valuable cooling time by intermittently operating. By shutting down after a short period of operation, this prevents continuous heat accumulation and keeps component temperature rise within a safe range, thus preventing burnout due to overheating.
2,Reducing component electrical stress:
A continuous short circuit generates a large inrush current when the power switches turn on. Burst mode typically employs a "soft start" at the beginning of each cycle, which mitigates this current stress to a certain extent and improves component reliability.
3,Achieving automatic recovery:
Unlike a one-time fuse, hiccup mode is a reversible protection. Once the overload or short circuit fault at the load is resolved (for example, by unplugging the short-circuited device), the power supply automatically detects normal operation during the next restart cycle and resumes normal operation, eliminating the need for manual fuse replacement or power cycling. This greatly improves the usability of the device.
B,Effect on customer equipment (protection of loads and equipment systems)
1,Providing Fault Warnings:
"Hiccup" mode is typically accompanied by periodic fluctuations in the output voltage (for example, jumping from 0V to a normal voltage and then back to 0V). Experienced engineers can determine that a system overload or short-circuit fault has occurred by measuring the output voltage or observing connected devices (such as a flashing indicator light). This provides a clear fault signal.
2,Limiting Fault Energy to Prevent Fault Expansion:
When in "hiccup" mode, the power supply outputs intermittent, limited power pulses rather than continuous full-power output.
If the load device is overloaded due to a short-circuited component, this limited energy can prevent more severe damage to the faulty component (such as explosion or fire), thereby minimizing the scope of the fault and facilitating repairs.
3,Maintaining System Safety:
By protecting the power supply from burning out, "hiccup" mode indirectly protects the entire power system. A burned-out power supply could cause dangers such as smoke and fire, and could even introduce faults to the power grid or other connected equipment. "Hiccup" mode eliminates risks before they escalate.
Therefore, "hiccup-style" overload protection is an excellent design that takes into account the safety of the power supply itself, load equipment protection and user experience, and is an important guarantee for the reliability and safety of modern switching power supplies.
