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While looking at existing designs in the company that I recently started working at, I noticed many times that designers take for Example a DC-DC and add extra outputs that have the same name, and then they connect them to the same node:

enter image description here

This is a Richteck DC-DC that has the following Application Circuit:

enter image description here

What is the reason for that?

Note: Notice that the same principle here is applied for PVDD.

Firas Abd El Gani
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    Internally they might be the same node, but many pins/bonds are used for lower inductance/resistance and higher power dissipation. – Wesley Lee Dec 09 '20 at 15:51
  • Does this answer your question? [Need for 2 drains in a MOSFET?](https://electronics.stackexchange.com/questions/459029/need-for-2-drains-in-a-mosfet) – Wesley Lee Dec 09 '20 at 15:53
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    Another reason on the CAD side is that the footprints (say QFN-20) will have a standard numbering on the pads (1 to 20) and on the schematic symbol you will want to connect all of them without having to have a footprint per device, so you create many symbolic pins with same name but pointing to different pads. – Wesley Lee Dec 09 '20 at 15:56

4 Answers4

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A pin or bump on an IC has a maximum current it can handle for thermal and electromigration reasons. There's also potentially unwanted inductance and resistance in series with the pin due to bond wires.

For that reason, on higher current connections IC designers often use multiple pins in parallel to split the current between them and lower the associated parasitics and even the thermal impedance.

This will improve performance and reliability.

John D
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Having multiple pins for the same output, or power supply, or ground, allows heavier currents to flow through these outputs, power rails or grounds, than a single pin would allow.

It is equivalent to just having a wider/heavier pin.

Math Keeps Me Busy
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Look at the physical implementation of the device: -

enter image description here

  • There are 3 pins called LX (numbered 13, 14 and 15) and they all need to be joined together - reason; to maximize the current out-of the chip. They are outputs.

  • Same reason for PVdd (numbered 10, 11 and 12). This is the input power connection and multiple pins are used to maximize the current into the chip.

  • PGND is the same.

Andy aka
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One is a schematic for a PCB, where you need a physical connection.

The other is a data sheet, where you need clarity. Multiple pins allow for higher currents, but they can become confusing on datasheets.

StainlessSteelRat
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