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UCC27712: UCC27712 Not sufficient air and creepage distance from pin 6(HS) to pin 5 (LO)

Holger Tuerk1
Prodigy 10 points
Part Number: UCC27712
Other Parts Discussed in Thread: UCC27714

The case of the UCC27712 is a SOIC-8 with a 1.27mm grid dimension and a spacing
between the pads of 0.67mm maximimum.
So pin 6 ( HS) which is the drain of the lower mosfet is only 0,67mm away from pin 5,
which is the the gate of the lower mosfet, which is 16V away from source potential.
EN 61010 recommends 1.5 mm A&C for circuits supplied from 320V mains and CATII
Commonly used Mosfets as DPak recommend a PCB layout spacing of greater than 1.5mm between Source / Gate
and Drain connections for safety reasons.
In dirty environment or humidity the dimensions of the driver package could be critical.
A coating could be mandatory,  finally driving the costs.
What are the basic ideas and proposals from TI?
Regards
Holger Tuerk

  • 0
    TI__Mastermind 23105 points

    Hello Holger,

    Thank you for the interest in the UCC27712 gate driver. There are a number of SOIC-8 pin package 600V half-bridge drivers in the market with various pin out configurations. With the SOIC-8 package with any pin configuration there will be a floating high side driver referenced pin next to the low voltage pins in this package.

    The determination if this pin spacing is a concern does depend on the application, with the important factors being pollution degree and humidity. The SOIC-8 does provide a smaller package than the SOIC-14 which is the package required to achieve high spacing of the high voltage pins and the low voltage pins. Ins some applications there is a board coating required for other reasons than just the driver IC, and the SOIC-8 provides a smaller package in this case.

    The UCC27714 in the SOIC-14 package does achieve the target spacing you mention where this is critical in the application. This driver is also a 600V half bridge driver with higher drive strength of 4A which achieves the pins spacing you are seeking.

    Please confirm if this addresses your concerns, or you can post additional questions on this thread.