06 May 2010
Analog Devices introduced a 4-A dual-channel isolated gate driver integrated with ADI’s iCoupler digital isolation technology. Analog Devices’ new dual-channel gate driver is effective for driving high-voltage switching FETs (field-effect transistors) in synchronous rectification dc-to-dc converter applications. By integrating digital isolation and a 4-A gate driver into a small, industry standard SOIC (small-outline integrated circuit) package, the ADuM3220 replaces traditional discrete gate driver solutions, saving up to 70 percent of the board space and reducing costs by up to 30 percent for small dc-to-dc module designs.
Discrete offerings use separate components for isolation and gate drive, including large, difficult to use pulse transformers and optocouplers that provide poor performance and degrade over time. The new ADuM3220 dual-channel gate driver offers better propagation delay (60 ns max) and channel-to-channel skew (5 ns max) than competitive products, along with excellent reliability associated with CMOS-based digital isolation.
“Working closely with our power supply customers, we learned that many designers use discrete isolators and gate drivers, which can take up quite a lot of board space,” said Peter Henry, vice president, Power Management Products, Analog Devices. “ADI’s iCoupler digital isolation technology integrates the gate driver function with two channels of high-performance digital isolation technology; this radically simplifies design and reduces design costs.”
The ADuM3220 4-A dual-channel isolated gate driver provides two independent isolation channels and operates with an input supply voltage ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems. Each output may be operated from 7 V to 18 V to support typical gate driver voltages for synchronous dc-to-dc converters. The outputs of the ADuM3220 dual-channel gate driver default to a logic-low state, preventing both gate drivers from being on at the same time and eliminating potential damage of the high-voltage FETs. In addition, the ADuM3220 dual-channel gate driver operates over a wide -40ºC to 125ºC temperature range.
In comparison to gate drivers employing high-voltage level-translation methodologies, the ADuM3220 dual-channel gate driver offers the benefit of true galvanic isolation between the input and each output, enabling voltage translation and safety isolation across the isolation barrier. The ADuM3220 has 2.5 kVrms isolation rating with UL (Underwriters Laboratories), IEC (International Electrotechnical Commission) and VDE (Verband der Elektrotechnik) certifications pending.
Designed to work well with ADI’s power management products, complementary components for the ADuM3220 dual-channel gate driver include the ADP1043 digital controller; ADP125 linear regulator; ADP1621 current-mode, step-up dc-to-dc controller; ADP1828 step-down, dc-to-dc controller; and ADIsimPower™ design tool.
With more than 350 million channels deployed, ADI’s proven iCoupler technology is based on chip-scale transformers, rather than on the LEDs and photodiodes found in optocouplers. Transformers support higher data rates, consume less power, and are more stable over life as compared to LEDs and photodiodes. By fabricating the transformers directly on-chip using wafer-level processing, iCoupler channels can be integrated with each other and other semiconductor functions at low cost. iCoupler transformers are planar structures formed from CMOS and gold metal layers. A high breakdown polyimide layer underneath the gold layer insulates the top transformer coil from the bottom. CMOS circuits connected to the top coil and bottom coil provide the interface between each transformer and its external signals.
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