Skip to main content

Eccentric Rotating Mass Motor Control

Using GreenPAK™ with low dropout regulators (LDOs), provides a fully customizable, low-power solution to drive and control a wide variety of small ERM motors appropriate for devices such as mobile phones, game controllers, etc. The programmable digital and analog resources in GreenPAK make it easy to implement custom features to differentiate your haptic experience as well as protection features to ensure smooth and safe operation, including:

Custom vibration strength

Custom vibration patterns and timing

Braking

Custom motor kick-start and

Over-current/short circuit protection

Over-temp protection

 

GreenPAK Benefits for ERM Motor Control

Flexibility

  • GreenPAK VDD is 2.5 to 5.0 V
  • GreenPAK has integrated delays for programmable button de-bounce
  • GreenPAK’s Inter-Integrated Circuit (I2C) interface allows changes to vibration patterns and timing
  • GreenPAK general-purpose input/output (GPIO) routing is flexible – Ensuring the least complexity in PCB routing

Power Consumption

  • GreenPAK is low-power

System Stability

  • GreenPAK has integrated LDO protection
  • GreenPAK is Zero Code – Implementing features in hardware ensures stability
  • GreenPAK can integrate many components ensuring fewer points of failure
erm

Vibration Patterning and Strength

Protection

Using GreenPAK’s programmable digital and timing blocks it is possible to make a number of different vibration patterns. With the LDOs integrated into the GreenPAK, which can switch between two voltage outputs using digital logic and up to 32 different levels via I2C, it is also possible to create vibrations of different strengths.

Kickstart

  • To quickly start an ERM motor, it is useful to drive it at a higher voltage for a short duration. This overcomes the momentum of the still mass and allows for cleaner vibration patterns.

Braking

  • Some ERM motors include a special pin for braking. Using digital logic and GreenPAK’s configurable GPIO, driving the braking pin anytime the motor should stop is easy.

Pattern and Kickstart Circuit in GreenPAK
 

 

The LDOs in GreenPAK contain over-current and short circuit detection which will cause the LDO to shut down in the event of a failure. Additionally, using the integrated temperature sensor and programmable analog comparator (ACMP), it is easy to implement over-temperature shutdown as well.

                       

Overcurrent & Short Protection LDO Settings 
 
 
Over-temperature Protection Circuit in GreenPAK

 

View the full list of the GreenPAK videos in our Training Video Library.