Customer’s Firmware Team Acquires Power Management Expertise During Product Development

Challenge: Battery Life Requirements Meet Knowledge Gap

 
A medical device manufacturer’s firmware team with experience in wall-powered products faced a new challenge: optimized firmware for a battery-powered device with an 18-month lifespan. Their existing firmware approach of polling sensors every 100ms and maintaining continuous wireless connectivity would result in a lifespan of only six weeks with the chosen 2600mAh lithium battery, falling short of the customer’s needs.

The engineering manager needed the product to ship within the planned 14-week timeline while building internal capability for future low-power consumption products. Traditional training programs for their software engineers would require 3-4 weeks before implementation could begin, creating unacceptable schedule risk. Thus, a new approach from a team with software expertise in battery-powered devices was essential for the manufacturer’s timeline to be met.

Integration Approach: Embedded Learning Through Development

DE Design Works embedded (pun intended) a firmware specialist directly within the client's firmware development team rather than operating as an external contractor. The arrangement structured knowledge transfer through active development work across three areas:

Pair Programming Sessions: The DE firmware engineer worked directly with the client’s firmware team members through collaborative design meetings and implementation to achieve the optimal firmware power management features for the specific embedded device PCB design. Sometimes this meant our engineer meeting directly with the client’s team members to explain design decisions in real-time while actively making code changes. This allowed for the whole product team, not just the DE firmware engineer, to understand both the theory behind those decisions and how they are implemented in a real codebase.

Code Review Integration: All of the code changes underwent collaborative review sessions where the DE specialist had the opportunity to explain low-power implementation choices such as how the changes integrated into the existing electronics architecture, low-level to high-level data flow from the power measurements, and built-in error handling for common fail cases.

Measurement and Validation: Joint sessions using power analyzing equipment like oscilloscopes and current meters demonstrated real-time current consumption, teaching the customer engineering team to correlate the code changes with measurable power consumption.

Technical Implementation Details

The firmware power optimization process addressed four primary areas:

Microcontroller Sleep States: Replacing continuous polling with interrupt-driven architecture using ARM Cortex-M4 stop modes allowed the microprocessor to enter the deep sleep state more often and for longer periods of time. This resulted in a sleep state current drop from 12mA to 180µA, a 98.5% reduction.

Peripheral Management: Implemented selective peripheral shutdown sequences for unused ADC channels, communication interfaces, and GPIO pins. Each optimization session included before/after current measurements to demonstrate power consumption impact.

Wireless Protocol Optimization: Modified Bluetooth Low Energy connection intervals from 20ms to 400ms during idle periods, reducing average radio current from 8mA to 1.2mA. The team learned to balance power consumption against response time requirements.

Sensor Duty Cycling: Converted continuous sensor monitoring to scheduled measurement windows, reducing sensor power consumption by 85% while maintaining clinical accuracy requirements for the device.

Knowledge Transfer Outcomes

The collaborative approach produced both immediate project results and long-term capability development for the customer:

Project Delivery: The embedded device achieved a 19.5-month battery life, exceeding the 18-month requirement, all while staying within the original 14-week firmware development timeline. DE was able to on-board our experienced firmware engineer, have them analyze and assess the current codebase and product functionality, collaboratively design and implement new firmware updates, product test, and deliver the new firmware all without any schedule delays or adaptations.

Team Capability: Post-project assessment showed the firmware team could independently implement similar power management techniques into other embedded products. Subsequent projects required minimal external consultation for power-related decisions.

Documentation Package: The engagement produced practical resources including power measurement procedures, embedded code templates for common low-power pitfalls, and troubleshooting guides for power-related issues.

Measurement Competency: The team acquired proficiency with power consumption analysis equipment and techniques, enabling accurate power budgeting for future projects.

Quantified Results

Power consumption targets were met across all operational modes:

  • Deep Sleep: 180µA (target: <200µA)
  • Sensor Active: 2.1mA (target: <2.5mA)
  • Wireless Transmission: 15mA (target: <18mA)
  • Overall Battery Life: 19.5 months (target: 18 months)

The firmware team demonstrated competency through successful implementation of power management in their next project without external assistance, completing power optimization 2 weeks ahead of schedule.

Long-term Impact

Six months after project completion, the firmware team had applied learned techniques to three additional battery-powered products. The measurement and optimization procedures developed during the engagement became standard practice for all new embedded products requiring battery operation.

The engineering manager reported that power management expertise eliminated the need for external consultation on subsequent low-power optimization projects, providing both schedule control and cost reduction for future development efforts.

This approach of learning through collaborative active development, rather than traditional classroom-based technical training, has been shown to reduce knowledge acquisition time by 60-70% compared to its traditional counterpart. When paired with experts in their field who have the formal background and direct application-based experience like our firmware engineers at DE Design Works, a more focused and applied knowledge transfer can occur while still providing a broad understanding of the topics addressed.

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Frequently Asked Questions

What types of power management circuits does DE Design Works design?

DE Design Works designs the full spectrum of power management electronics: switching regulators (buck, boost, buck-boost, flyback, SEPIC), low-dropout (LDO) linear regulators for noise-sensitive analog and RF circuits, battery management systems for Li-Ion, LiFePO4, and lead-acid chemistries, UPS and holdup circuits, multi-rail power sequencing systems, and energy harvesting circuits for solar and vibration sources. Topology and component selection are driven by efficiency requirements, input/output voltage ratio, and thermal constraints.

How do you design a power supply that passes EMC/EMI testing on the first attempt?

Passing EMC on the first attempt requires design discipline throughout: place bypass capacitors as close as possible to IC power pins, route switching regulator hot loops (the high-di/dt loop) as small-area as possible, use a solid ground plane with no splits under the switching converter, select inductors and capacitors rated for the switching frequency, and add common-mode filtering at the input. Spread-spectrum frequency hopping in the switching controller reduces peak emissions. DE Design Works pre-compliance tests all power designs before formal EMC certification to catch issues early.

What is power sequencing and when is it required in an embedded system?

Power sequencing ensures that voltage rails in a multi-rail system come up and go down in the correct order to prevent damage to sensitive ICs. FPGAs, DDR memory, and processors typically require their core voltage to power up before I/O rails, and may require specific timing between rails. DE Design Works designs power sequencing using dedicated sequencer ICs (e.g., TI TPS3431, Renesas ISL6366) or supervisor circuits, and validates sequencing with oscilloscope measurements across all operating conditions including brown-out recovery.

How does DE Design Works approach battery charger design for portable products?

Battery charger design starts with chemistry selection (Li-Ion, LiFePO4, NiMH) and cell configuration (series/parallel), then specifies the charge algorithm (CC/CV for lithium, trickle/fast for NiMH), protection requirements (overvoltage, undervoltage, overcurrent, overtemperature), and thermal management for the charging circuit. DE Design Works selects charger ICs with proven track records (Texas Instruments BQ series, Maxim MAX series), implements cell balancing for multi-cell packs, and validates thermal performance under worst-case ambient and charge current conditions.

What efficiency benchmarks should a switching power supply hit for modern IoT and industrial products?

Modern buck regulators can achieve 90–97% efficiency at nominal load. For IoT products with light-load operation (< 10% of full load), selecting a regulator with a low-quiescent-current pulse-frequency modulation (PFM) mode is critical — a 10µA Iq regulator at 1% load can mean the difference between 6-month and 5-year battery life. For AC/DC designs, Energy Star and IEC 62368 efficiency requirements apply. DE Design Works documents efficiency at 25%, 50%, 75%, and 100% load for all power supply designs and compares against applicable standards.