Wearable devices have become a daily part of consumer’s lives, but batteries never last long enough. The battery-life problem continues to degrade the user experience due to the frequent need to recharge or replace batteries. However, recent advancements in low power technology​ are changing the game. In this webinar, we've teamed up with the experts from Ambiq Micro, leading provider of low power semiconductors, to share what's possible with lower power consumption and how energy efficient architectures enable new and different use cases across a variety of industries.

1. How Lower Power Consumption is
Transforming Wearables and
Enabling New Use Cases
Scott Hanson
CTO and Co-Founder
Ambiq Micro

2. The World’s Most Energy-Efficient ICs
2
Ambiq Micro offers the world’s most energy-
efficient MCUs and SoCs for wearables…

3. The World’s Most Energy-Efficient ICs
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…and the broader IoT

4. The Battery-Powered Internet of Things
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The future of IoT is exciting – but not if we need to
replace billions of batteries per day/month/year
[Image source: Cisco]

5. Battery Strain in Wearables
• Segment display
• Basic watch functions
• Multi-year battery life
5
• High res color display
• Basic watch functions
• Motion/activity tracking
• Heart rate monitoring
• GPS tracking
• Altimeter
• Thermometer
• Bluetooth radio
• Days/weeks battery life

6. Battery Strain in Wearables
• Segment display
• Basic watch functions
• Multi-year battery life
6
• High res color display
• Basic watch functions
• Motion/activity tracking
• Heart rate monitoring
• GPS tracking
• Altimeter
• Thermometer
• Bluetooth radio
• Days/weeks battery life
Smaller, thinner
industrial designs
New functions
(cellular radios, new
biosensors, more
sensor analysis, etc.)
New use cases
(e.g., smart clothing
with 1+ year life)

7. No Easy Solution with Batteries
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Batteries just aren’t improving fast enough!

8. The Other Side of the Energy Equation
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Component Power Consumption
Display 10-100mW
MCU/CPU 0.1-10mW
Radio 10-30mW
Heart Rate Monitor 0.1-1mW
GPS Receiver 10-100mW
Power Management 10-20% of system power
MCU Radio
Display Sensor
PMIC
370mWh battery
24h/day * 7 days
= 2.2mW average power for 1 week life
675mWh battery
24h/day * 14 days
= 77µW average power for 1 year life
24h/day * 365 days

9. Addressing the IC Energy Problem (1/3)
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Moore’s Law has been one of the strongest drivers
of energy efficiency gains
[Dreslinski et al., Proc. of the IEEE, 2010]

10. Addressing the IC Energy Problem (2/3)
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• Growing “menu” of transistor options provide flexibility
• Increasingly, small transistors are also low leakage
• New device architectures offer promise

11. Addressing the IC Energy Problem (3/3)
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0 Volts
1.2 Volts
0 Volts
0.3 Volts
Energy ~ (Voltage)2
Conventional Circuit Design Sub-threshold Circuit Design
Sub-threshold design was first conceived >30 years ago, but
Ambiq was the first to build a comprehensive platform

12. We’ve Come a Long Way
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Texas Instruments
MSP430
Ambiq Micro
Apollo2
Improvement
Launch Date 2003 2016 --
Processor Core 16b Proprietary Core 32b ARM Core --
Max Speed 8 MHz 48 MHz 6X
Flash 60 kB 1 MB 17X
RAM 2 kB 256 kB 128X
Power Consumption
Per Clock Cycle
440 µW/MHz 33 µW/MHz 13X
Power Consumption
Per Unit of Work
400 µW/Coremark 14 µW/Coremark 29X
Today’s best in class processor is 29X more energy efficient
than the best in class processor in 2003

13. Addressing the Radio Energy Problem
• New protocols have emerged
• IC technology and architectures have improved
• Application level techniques have proliferated (e.g., duty cycling)
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Average power of ~10µW for idle
BLE connection at 1s interval

14. Addressing the Display Energy Problem
• New display technologies have emerged
• Gesture/motion detection have also helped
• New technologies will continue to emerge
14
Electrophoretic Displays
(Today)
MicroLED Displays
(Emerging)
[Courtesy Plessey][Courtesy eInk]

15. New Use Case: Battery-Free Wearables
• When energy gets low enough energy harvesting is possible
• Sources of energy can include temp differential, solar, RF, etc.
• Becomes a complex system challenge
15
[Source: datasheet for Marlow EHA-PA1AN1-R03]

16. New Use Case: The Embedded Coach
• Wearables collect – and discard – huge amounts of data
• It’s impractical to store data, so we must analyze on the fly
• We can then use this data to deliver coaching
• All of this is being enabled with improving CPU efficiency
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Sensor Type Data Collected Per Min Possible Uses of Data
Accelerometer,
Gyro
~70 kB
Activity recognition, gesture recognition,
posture analysis, skills assessment, etc.
Heart Rate
Monitor
~40 kB
Real-time HR zones, HR
recovery/response, VO2 and VO2 max,
cardiac efficiency, pulse pressure, etc.
Microphone ~1.9 MB
Keyword detection, context detection,
respiration analysis, etc.

17. New Use Case: Intelligent Wearables
• Neural networks emerging as an incredible tool
• Applications include activity recognition, skill
assessment, gait analysis, emotion recognition, etc.
17
Hannink et al, “Sensor-based Gait Parameter Extraction with Deep Convolutional Neural Networks”

18. The Next Energy Problem to Solve
• Basic computation is simple – multiply accumulate (MAC)
• Number of MACs can be enormous and continuous
• This is a new energy problem to solve
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Application
Estimated
MMAC/s
Estimated
Model Size
Source
Keyword
Detection
33 140 kB
Arik et al, “CNNs for
Small-Footprint
Keyword Spotting”
Gait Analysis 74 48 MB
Hannink et al, “Sensor-
based Gait Parameter
Extraction with Deep
CNNs”
Abnormal
Heart Sound
Detection
4600 12 MB
Rubin et al,
“Recognizing Abnormal
Heart Sounds Using
Deep Learning”

19. No Easy Answers for Low Power
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We’ve come a long way to enabling ultra-low power
wearables – and there is still a long way to go