Tool/software:
Hi,
We would like to inquire about the insulation lifetime of TI’s reinforced isolation gate drivers, such as the UCC21551, particularly under high-frequency switching stress.
According to Figure 5-5 in the datasheet, the insulation lifetime is estimated to be around 29 years at 1500 VRMS and 60Hz, based on a TDDB (Time-Dependent Dielectric Breakdown) model. We understand this model assumes low-frequency AC stress, such as power line frequency.
However, in our application (e.g., LLC converters and totem-pole PFC), the isolation barrier is continuously exposed to high-frequency switching voltages around 100kHz, along with fast dv/dt transitions.
Could you provide TI’s official perspective on how such high-frequency switching (e.g., 100kHz) may affect the insulation lifetime?
We are particularly interested in whether the TDDB-based lifetime projections in Figure 5-5 remain valid under high-frequency stress, or if the lifetime may be significantly reduced due to:
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Increased switching cycle count,
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Higher dv/dt stress,
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Possible partial discharge mechanisms.
If our understanding is correct, and if there are any recommended design considerations (e.g., derating guidelines) or relevant application notes discussing this topic, we would highly appreciate your guidance.
Thanks,
Conor
