CMOS-Based Isolated Gate Drivers Provide Drop-in Replacements for Opto-Drivers

December 10, 2013 | 14:37
CMOS-Based Isolated Gate Drivers Provide Drop-in Replacements for Opto-Drivers
CMOS-Based Isolated Gate Drivers Provide Drop-in Replacements for Opto-Drivers

Failure-prone opto-drivers are a weak link in motor controls and other industrial power systems that require long-term reliability, extended warranties and fail-safe operation for up to 20 years. Opto-drivers are inherently limited by their inferior LED-based technology, which is subject to large output variations over input current, temperature and age. These variations are eliminated when using the new digital CMOS-based  Si826x isolated gate drivers from Silicon Labs that support up to 5 kV isolation ratings and up to 10 kV surge protection,. Less variability, especially in input turn-on current, simplifies system design since developers no longer need to anticipate aging effects.

 

The Si826x family is a pin- and footprint-compatible functional upgrade solution for commonly used opto-driver products. The isolated gate drivers emulate the behavior of opto-drivers by modulating a high-frequency carrier instead of light from an LED. This simpler digital architecture provides a robust isolated data path that requires no special considerations or initialization at start-up. While the input circuit mimics the characteristics of an LED, the Si826x devices require less drive current, resulting in higher efficiency. The propagation delay time of the new devices is independent of the input drive current, resulting in consistently short propagation times (25 ns), smaller unit-to-unit variation and greater input circuit design flexibility.

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