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Isolated Gate Drivers Have Digital CMOS Design

Isolated Gate Drivers Have Digital CMOS Design

Silicon Labs introduced the industry's first digital CMOS-based drop-in replacement solution for optocoupler-isolated gate drivers (opto-drivers). Supporting up to 5 kV isolation ratings and up to 10 kV surge protection, the new Si826x isolated gate drivers provide an ideal configuration, package and footprint fit for a wide range of opto-drivers used in high-power motor control, industrial drives, solar power and EV/HEV inverters, and switched mode and uninterruptible power supplies.

Based on Silicon Labs' proven digital isolation technology, the Si826x family is a pin- and footprint-compatible functional upgrade solution for commonly used opto-driver products. Si826x 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 Si826x 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.

The propagation delay and skew of Si826x isolated gate drivers is ten times lower than opto-drivers, which improves response time for feedback loops and enhances system efficiency. The Si826x devices also provide superior noise immunity, enabling robust, glitch-free long-term performance in harsh, noisy environments such as industrial motor control. Unlike opto-drivers, isolated gate drivers offer stable performance over time and temperature with no drift. Because of these advantages, the Si826x family provides longer service life and significantly higher reliability than opto-drivers.

The Si826x gate drivers are ideal for driving power MOSFETs and insulated gate bipolar transistors (IGBTs) used in motor control and power inverter applications. Supporting gate drive voltages of up to 30 V and peak output current ranging from 0.6 A to 4.0 A, the Si826x devices provide best-in-class drive strength for MOSFET and IGBT applications, ensuring fast turn-off and turn-on of external switching transistors for maximum efficiency.

Samples and production quantities of the Si826x isolated gate drivers are available now in four package options: SOIC-8 (3.75 kV isolation rating), GW DIP-8 (3.75 kV isolation rating), SO-6 (5 kV isolation rating) and LGA-8 (5 kV isolation rating). Because these package types are pin- and footprint-compatible with popular opto-driver packages, there is no need to change existing designs or printed-circuit board (PCB) layouts to make the easy drop-in switch to isolated gate drivers. The Si826x family also supports a variety of output currents. The Si8261Ax device has an output current drive capability of 0.6 A while the Si8261Bx is capable of driving up to 4 A. The Si8261xAx device has an output under-voltage lockout (UVLO) of 5 V while the Si8261xBx has an 8 V UVLO and the Si8261xCx has a 12 V UVLO option.

Si826x family pricing in 10,000-unit quantities begins at $0.71 (USD). To help developers evaluate the performance of the Si826x family, Silicon Labs offers the Si826xDIP8-KIT evaluation kit, available now for $29 (USD MSRP). The evaluation board is flexible enough to allow both hook-up to lab equipment for detailed specification evaluation as well as connection to the customer's existing board.

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