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UCC14240-Q1: Layout for VEE and GNDP pin

Part Number: UCC14240-Q1

There are multiple pins for GNDP and VEE pin of the UCC14240-Q1 device, we know they could be for the high current rating and power dissipation. 

Customer would like to know which pin is much close to the die? For example: Pin 8 to Pin 18 are connected to the GNDP on the die. which pin is much close to die or much short distance with bounding wire to the die? since customer is considering how to optimize the layout. thanks. 

  • Hi Brian,

    From a thermal point of view, all GNDP and VEE pins are treated the same. Refer to the UCC14240EVM User Guide PCB images in section 6. Electrically, the input capacitors should connect between VIN (pins 6,7) and GNDP (pins 8,9) for the most direct internal connection into the power stage. On the secondary side, the VDD-VEE capacitors should make a direct connection between VDD (pins 28,29) and VEE (pins 30,31). Also, for best possible output voltage regulation, pay attention to the VEEA pin (pin 35). The VEEA pin (pin 35) is the same as the VEE pins but it is separated as the pin "closest to the die" to address the exact question you asking. The lower feedback divider resistor should be referenced to VEEA because this is the internal feedback comparator is referenced to this pin. It helps to sperate the GNDP and VEE, VEEA pins as I'm showing in the schematic below. Drawing the schematic this way and following the User Guide example will also help the PCB designer to understand how best to design the GNDP, VEE planes and how to route the VEEA connection.

    Regards,

    Steve M