Figure 30. Brown-In/Out and input OVP: external

configuration (Only BR)

Figure 31. Brown-In/Out and input OVP: external

configuration (No input iOVP nor BR)

5.15

Frequency jittering for EMI reduction

Although the VIPERGAN50 works in QR mode and the switching frequency is already modulated at twice the

mains frequency, it implements a proprietary frequency jitter technique to further reduce EMI. This technique is

based on the injection, on the current sense signal, of a square waveform at 10 kHz (above the feedback loop

bandwidth) with 50 % duty cycle which modulates the amplitude of the peak primary current. The percentage of

this amplitude modulation is set as a default at 5 %. As the peak current reduces with decreasing load levels, the

effect automatically attenuates at lower loads, where the energy of EMI noise is highly reduced.

5.16

Thermal shutdown protection

When the controller temperature exceeds the shutdown threshold, TSD (140 °C typ.) the device is shut down and

maintained off for the time TSD-REST (2 s typ.) to prevent any dangerous overheating of the system and the VDD

pin is continuously recycled between VDD-ON and VDD-OFF to keep the controller alive. During this time the IC

consumption is reduced to IDD-FAULT to further minimize the HV start-up losses.

After TSD-RESTART, the IC restarts as VDD reaches VDD-ON.

Please note that the thermal sensor is embedded into the controller chip and the power GAN chip may have a

higher temperature.

The OTP timing diagram is shown in Figure 32.

Figure 32. OTP timing diagram

VIPERGAN50

Frequency jittering for EMI reduction

DS13888 - Rev 2

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