Isolated gate drivers step up noise immunity in power electronics

March 02, 2016 // By Graham Prophet
A family of isolated gate drivers solves, says Silicon Labs, a critical need for cutting-edge power supply designs; the Si827x ISOdriver family provides highest noise immunity for power supplies, solar inverters and EV/HEV chargers

Based on Silicon Labs' digital isolation technology, the ISOdriver family claims the highest noise immunity of any gate driver on the market; its common mode transient immunity (CMTI) suits the drivers for fast-switching and potentially noisy power supply systems.


To maximise power per volume (W/mm ³) power density, many designers choose faster switching frequencies for their modulation schemes. Power delivery systems use high-power semiconductor switches, such as silicon-based MOSFETs and new gallium nitride (GaN) and silicon carbide (SiC)-based MOSFETs, requiring a high-current isolated driver to control the switch. Fast switching improves system efficiencies but also produces higher noise transients that can cause signal loss or permanent damage from latch-up. The Si827x gate drivers protect power systems by offering exceptional immunity to these noise transients caused by high-speed switching.


The gate drivers offer noise immunity of 200 kV/µsec and latch-up immunity 400 kV/µsec - twice the immunity rating of any other gate driver available. This eliminates risks posed by faster switching speeds, preventing modulation loss as well as latch-up, which can be a major safety concern. The Si827x family's very high latch-up specification makes the gate drivers extremely robust, preventing permanent latch-up damage.


The Si827x family offers a choice of single- or dual-isolated drivers with either two independent input controls or a single input for power converter applications. The drivers operate with a wide range of 2.5 - 5.5V input VDD and a maximum drive supply voltage of 30V. The lower VDDI voltage capability of 2.5V enables developers to design systems with a low-voltage power supply that consumes less power, and increases system efficiency.


The gate drivers feature an EN (active high enable) pin instead of the typical DIS (active low) pin, under-voltage lockout (UVLO) fault protection, a de-glitch feature for filtering noisy inputs and highly precise dead time (DT pin) programmability. Using this DT feature, developers can precisely control the "dead time" between two switching