Choosing GreenPAK™ at the very beginning of your project is a perfect decision to avoid unforeseen issues from the start. Choosing an MCU with the exact right amount of IO at the beginning of a project may be difficult as new requirements often creep in and some unforeseen engineering challenges occur during development. Adding differentiation to your project can be challenging as well since most MCUs available are available to everyone.

Many new GreenPAK devices include an I2C block which makes these components perfect for an ideal GPIO expander allowing you to add new features, logic, timing, and sensing to already highly integrated designs.

GreenPAK Benefits as GPIO Expander


GreenPAK Enhances System Stability

  • 100% hardware to ensure stability
  • Integration of many components to ensure fewer points of failure

GreenPAK Lowers Power Consumption

  • Low power consumption for the best performance

Configurable GreenPAK Pinout

  • GreenPAK GPIO routing is flexible ensuring the least complexity in PCB routing

GreenPAK Reduces Board Size

  • Being as small as 1.2 mm² it is a perfect solution for mobile and wearable electronics.

GreenPAK Maximizes GPIO Flexibility

  • Flexible signal routing – PCB layout and routing
  • Configurable I/O - Pull-up/down resistors
  • Customizable logic– Active-low/high
GPIO Expander

Expanding GPIO

Using GreenPAK's I2C block allows for easy expansion of both input and output. With simple I2C commands the matrix input of each component on the chip, including the GPIO, can be read, expanding input. With simple I2C write commands, I2C virtual inputs can push digital signals into the device or directly to GPIO.

I2C Virtual Inputs

I2C Virtual Inputs

I2C Readable Matrix Inputs

I2C Readable Matrix Inputs

Key Design Considerations

  • IO Configuration
    Configurable pull-up / pull-down resistors on GreenPAK's GPIO make communicating with any IC a snap.
  • Initial values
    Using GreenPAKs OTP NVM, it is easy to set initial output values
  • Latching during Write
    GreenPAK can be set to latch IO during write or update values as soon as a bit is written
  • I2C Speed
    GreenPAK I2C is 400 kHz
  • I2C Address
    GreenPAK I2C can have up to 16 unique addresses
  • Timing Adjustment and Additional Glue Logic
    GreenPAK has integrated LUTs, Inverters, DFFs, Counters


Resource Utilization

GreenPAK can often implement multiple functions in one small device. This isn’t limited to GPIO expansion applications. Just one GreenPAK device can implement glue logic, timing adjustment, reset, power sequencing, LED control, and more depending on design requirements and resource configuration.

All of GreenPAK 5 devices contain the needed I2C block for GPIO expansion and are only limited by the number of pins. Below is a chart of the maximum number of direct inputs or outputs achievable for each member of the family.

GreenPAK Output Expansion Input Expansion
SLG46531V 8 16
SLG46532V 8 15
SLG46533V 8 16


GreenPAK GPIO Expander Demo Board available for purchase. Please email us at [email protected] to learn more details.


Type Title Date
Other PDF 1.19 MB
Application Note PDF 285 KB
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