Product Review, Power Supply Fault

End User/Market: Retail Consumer

Background:

Consumer product, developed by a previous designer, with DC solenoids that control air flow through a manifold was experiencing a fault condition for a specific operating sequence. The microcontroller in the product was unexpectedly resetting.

Opportunity:

Determine the lowest cost, quickest to implement fix to eliminate the fault condition.

Solution:

Investigate previous designer's hardware design. Determine power supply transformer and fuse were undersized to meet maximum current requirements under certain solenoid-on conditions. Modify solenoid control firmware to reduce maximum current requirements to prevent unexpected resets.

Results:

Re-program each product in inventory with new firmware. Customer spared the time and cost of a new power supply design, hardware re-work and recertification for compliance with agency requirements.

Technologies:

PIC 16F88 microcontroller, C firmware, DC solenoid, power supply, agency requirements.