az143 – running freescale 8-bit mcus from single cell 1.5v ...standard microcontrollers do not...
TRANSCRIPT
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AZ143 – Running Freescale 8-bit MCUs from Single Cell 1.5V Batteries(v4)Jose PalazziSales Manager – South America
July, 2009
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Objective and Agenda
►Objective• Modern products require better effectiveness, reduced dimensions, and
increased autonomy. This session will show you how to run Freescale 8-bit MCUs from AA 1.5V batteries.
►Agenda• Why 1.5V?
Single cell operation requirements• Single 1.5V cell applications
Single cell applications with Freescale 8-bit MCUs and step-up converters• Step-up converter requirements & proposals
Battery characteristicsCase study: Flashlight with white LED supplied by AA 1.5V cell
– Circuit proposals– Performance analysis
What makes Freescale 8-bit MCUs suitable for single cell operation?• Conclusion
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…so, why 1.5V?
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Why 1.5V?
►1.5V batteries are readily available at low cost in many standard footprints
►Space-constrained applications require low power consumption and easy battery replacement
►Examples:• White LED light pens
Requirements: Size, reduced # of contact elements, longevity• Medical equipment – Data acquisition, hearing aid
Requirements: Ease of replacement, weight, quality of contacts.
• Industrial data loggers and telemetryRequirements: Size, weight, longevity
• IR remote controllersRequirements: Reduced # of contact elements, short duty cycles
• ToysRequirements: Size, cost, simplicity
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Single Cell Operation Requirements
►Most ICs do not operate directly from a 1.5V single cell• ~600mV drop voltage of silicon bipolar transistors and diodes• ~1V minimum gate voltage required for MOSFET devices to switch on
►Standard microcontrollers do not operate from 1.5V single cells• Memories and logic elements often require voltages starting from 1.8V
to start operating• Freescale Semiconductor offers MCUs such as the MC9S08QG4 which
can operate from 1.8V to 3.6V
►An associated step-up converter is required to boost voltage to 1.8V
• This presentation shows Freescale microcontrollers operating from single cell 1.5V batteries, and circuit topologies that show how to implement this kind of step-up conversion
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Single 1.5V cell applications
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First, Assume We Have a Step-up Boost Converter
►For now, think of this as a black box• Able to operate from 1.5V to 1.0V• Generating:
3.3V at 50mA (general purpose)4.0V at 100mA (white LED light)
►Topologies• We will see these later in the presentation• Now we will see how Freescale 8-bit MCUs fit these applications
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Wireless Humidity Sensor
► MC9RS08KA2• Low power RS08 MCU
operating from 1.8V to 5.5V• 2K byte single block FLASH• 63 byte RAM• Analog comparator• Precise and stable internal
oscillator• 8 pin SOIC
► Benefits• Extreme low cost
Disposable• Smaller footprint
Able to operate with watch batteries
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IF Remote Control
► MC9S08QG4• Lower power S08 MCU
operating from 1.8V to 3.6V• 4K Flash• 256 bytes RAM• Precise and stable internal
oscillator• 3 stop modes allowing very
reduced power consumption when no keys are depressed
• 16-pin TSSOP
► Benefits• Fewer contact elements
compared to 2-battery solutions• Smaller and lighter
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Motion/Presence Detector
► MC9S08QA2• Low power HCS08 core
operating from 1.8V to 3.3V• 10-bit SAR ADC converter• 8-pin SOIC
► Benefits• Lighter and smaller than 9V
powered systems• Efficient power saving
MCU wakes up, monitor ambient, sends data to host and goes to sleep again
• Able to operate from small solar cells
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MC9S08QA4/2
► HCS08 Core• S08 8-bit CPU @ 20 MHz• Voltage range 1.8v to 3.3v
► Memory• QA4: 4K Flash, 256 bytes RAM• QA2: 2K Flash, 160 bytes RAM
► Clock• Internal Clock Source (ICS)
10 Mhz BusFLLOn-chip oscillatorExternal crystal support 2% accuracy over full operating range
► Peripherals• 4-channel, 10-bit ADC• One ACMP• One 1-channel TPM• One 8-bit MTIM• 4-channel KBI
► Input/Output• 5 GPIOs and 1 output-only pin
► Power Saving Mode• Wait mode• Stop1, Stop2, Stop3 modes
S08 Core
256/160BRAM
MTIM 4-ch 10-bitADC
ICSCOPBDM
16-bit Timer1ch + mod
GPIO
Flash
4-ch KBI
RTC ACMP4KFlash
2KFlash
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Pocket MP3 Player with USB Interface and SD Card
►MC9S08JM32• Low-power HCS08 core• USB 2.0 Full Speed end point• 32 MB Flash memory• 2 KB RAM• 10-bit SAR ADC converter• SCI, SPI, I2C• 44-pin LQFP
►Benefits• Small, cost-effective audio
player with SD card• Easier to build
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MC9S08JM32Features / Benefits► 2.7 – 5.0V operation► 2x SCI, I2C, 2x SPI► 8 channel KBI► 16-bit timers: 1 x 2-ch, 1 x 6-ch► 12-bit 12-channel A-to-D converter► Analog comparator► Up to 51 general purpose I/O
Memory► 32 KB Flash► 2K RAM
Complete USB Solution► Integrated USB device ► Complimentary USB software Stack► CodeWarrior for Microcontrollers► Processor Expert
Packages► 64LQFP, 64QFP 48QFN, 44LQFP
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Full Speed USB 2.0 Device32K Flash
256 Bytes USB RAM
2K RAM
S08 Core
ICE+BDM
Indep. Clocked COP
2 SCI
2 SPI
KBI
IIC
RTC
MCG
6-ch., 16-bit Timer
Comparator
2-ch., 16-bit Timer
12-ch., 12-bit ADC
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Blood pressure meter
► MC9S08LL16• Low power S08 MCU operating
from 1.8V to 3.6V • 16 KB dual bank Flash • 2K RAM• 4 x 28 or 8 x 24 LCD controller
with integrated charge pump• Time-of-day module• 12-bit ADC with internal
temperature sensor• RUN, WAIT, two STOP modes
with fast wake-up Peripherals able to operate with core in stand-by
• 48-pin LQFP
► Benefits• High performance x power
consumption rate• Great system-level integration
with good battery autonomy• Easy battery replacement
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LCD Driver 9S08LL16 Packages
MC9S08LL16LCD Driver Block diagram Packages
Based on 8 backplanes 8x24 = 192 segments
Based on 4 backplanes 4x28 = 112 segments
48 & 64 LQFP
48 QFN
►Features• 1.8V to 3.6V• 20 MHz CPU speed• 8-ch keyboard interrupt• Up to 38 GPIOs • Up to 18 LCD pins mux with GPIO• LVD (low voltage detect)• Time-of-day module
►Internal Clock Source (ICS)• FLL• On-chip oscillator• External crystal support • 2% accuracy over full operating range
2K RAM
LL16: 16KLL8: 8K
ICE + 08BDM
COP
KBI
LL16: 2x2-ch 16-bit Timer
LL8: 1x2-ch 16-bit Timer
LCD Driver
IICS08 CoreLVD
TOD
ICS
SCI
SPI
8-12 bits ADC
Comparator
LL16 LL8
48 QFN
48 LQFP
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Extending Battery Life with MC9S08LL16 Clock Management
Time
Pow
erC
onsu
mpt
ion
Run Mode5 seconds elapsed, main application runs, increases bus frequency to complete task quickly
Run ModeSlower frequency bus to just take ADC reading
Stop3 with RTC EnabledExternal 32 kHz Osc.
Stop2 with RTC EnabledInternal 1 kHz Osc.
Run MCU in low-power run
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Home Care Thermometer
► MC9RS08LE4• Low power RS08 MCU
operating from 1.8V to 3.6V• Integrated LCD controller• 4K byte single block FLASH• 128 byte RAM• 10-bit ADC• 28-pin SOIC
► Benefits• Very low cost• Excellent integration – just a
few discrete devices outside• Smaller and lighter
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LCD Driver Packages
MC9RS08LE4LCD Driver 9RS08LE4 Packages
►Features• 2.7V to 5.5V• RS08 core• 1-20 MHz capability• 8-ch keyboard interrupt• Up to 26 GPIOs• LVD (low voltage detect)• RTI
►Internal Clock Source (ICS)• FLL• On-chip oscillator• External crystal support • 2% accuracy over full operating range
►Memory• 4K flash • 256 bytes RAM
256 RAM
4K Flash
RS08BDM 2x2-ch 16-bitTimer
LCD Driver8x14 or 4x18
ICSRS08 Core
SCI
RTI
COP
KBI
LVD
8-10 bits ADC 28 SOIC
Based on 8 backplanes 8x14 = 112 segments
Based on 4 backplanes 4x18 = 72 segments
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Isolated Current Meter
► MC9S08LL64• Low-power S08 MCU operating from
1.8V to 3.6V• 64 KB dual bank FLASH• 4K RAM• Integrated RTC• 12-bit SAR ADC• Internal temperature sensor• 288 segment LCD controller• Very low power stop modes – best in
class• 64-pin LQFP
► Benefits• Isolated and independent operation• Small footprint• Low irradiated noise• Could be powered by solar cells
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► Features• 1.8V – 3.6V operation• 2 x SCIs, IIC, SPI, KBI, TOD, ACMP• 2 x 2 ch 16-bit TPM• 10 ch 12-bit ADC• Vref1.2 (1.2v – 40 PPM/°C)• Up to 39 GPIO• 80LQFP/64LQFP package
► Memory• Dual bank 64K Flash • 4K RAM
► LCD Driver• Up to 288 segment LCD drive (8x mode)• BP/FP reassignment• Blink operation in low-power modes• Drive 3V and 5V LCD glass
► Internal Clock Source (ICS)• FLL• On chip oscillator• External crystal support (32 KHz, 1-16 MHz) • 2% accuracy over full operating range
► Scheduled Availability• November 2009
4K RAM
Flash32x2K=64K
BDM
COP
KBI
2x2-ch 16bit TPM
LCD Driver8x36=288
S08 Core LVD
ICS
2xSCI
SPI10ch-12 bits
ADC
IIC
TOD
Vref
MC9S08LL64
ACMP
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Step-up Converter Requirementsand Proposals
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Step-up Converter Requirements
►Important requirements:• Battery chemistry• Design requirements
Output voltageSupply current at no loadSupply current at nominal loadRegulation at full loadDynamicsEfficiencyIrradiated noise
►Consumers in general expect longer battery life in newer products►On the other hand, the evolution of battery-powered devices is driven
by the addition of even more power-consuming features
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Disposable Batteries
►Alkaline• Convenient, cheap and easy to find.• Long shelf life makes them excellent for
products such as emergency equipment• 1.6V to 0.9V practical operating range• Often available in AA and AAA footprints
►Lithium• Very low self-discharge rate.• Longer shelf life compared to alkaline• 1.8V to 0.9V practical operating range• Often available in CRxxxx footprints (aka button
battery)►Carbon Zinc
• Very low cost• High leakage resulting in reduced shelf life• 1.5V to 1.2V practical operating range• This full voltage is only available when little
current is drawn from the cell during its initial discharge. The voltage of the cell diminishes as the load to the cell increases
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Circuit Design
Portable flashlight with white LED supplied through a AA 1.5V cell
►Requirements:• Input voltage: 1.5V AA cell• Output voltage: 3.4V
While LED V_ak• Output current: 50 mA
Freescale MC9RS08KA2 MCU– 1.8V to 5.5V supply– Approx. 500μA/MHz consumption at 5V– Will operate at approx. 3.4V (limited by the LED)
White 5mm LED– 15000 mCd @ 45mA and 3.4V_ak
• Battery autonomy: 12 hours (continuous)
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Converter Requirements
►Supply requirements: • Vin_nominal: 1.5V• Vin_min: 1.1V
►Battery draining analysis:• Scenario 1: Converter efficiency from 80% to 93%
[ (3.4v * 50mA) / 0.80 ] / 1.1V = 193 mA max[ (3.4v * 50mA) / 0.93 ] / 1.5V = 122 mA min
• Scenario 2: Converter efficiency from 65% to 85%[ (3.4v * 50mA) / 0.65 ] / 1.1V = 238 mA max[ (3.4v * 50mA) / 0.85 ] / 1.5V = 133 mA min
►2500 mA/h AA battery lifetime in non-interruptible operation (*) • Scenario 1: (**)
0.94 * 2500mA/h / [ (193mA + 122mA) / 2 ] = 14.9 hours• Scenario 2: (**)
0.92 * 2500mA/h / [ (238mA + 133mA) / 2 ] = 12.4 hours
(*) Assuming linear behavior of I_dc drop over time for simple average(**) 0.94 and 0.92 as respective constant operation factors for 150 mA and 190 mAcontinuous operation
Scenario 1 = High efficient IC controller
Scenario 2 = Low cost discrete controller
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Proposal #1: Using an Integrated Step-up Converter
► Desired features• Low power, wide input range, able to start from
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Integrated Step-up Circuit Diagram
►Minor details such as button on MCU PTA5 and Step-up_pin6 omitted for clarity
►Current mode brightness control with Freescale MC9RS08KA2 ultra-low-cost MCU
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Integrated Step-up Circuit
►Implemented with evaluation boards
• Fast prototyping►Very efficient and precise
• Great brightness control►Operation from
1.5V to 0.9V• Long battery life
►Low noise operation►But complex and
expensive for a flashlight
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Integrated Step-up Facts
►Pros:• Great conversion efficiency• Excellent load regulation (even at zero load)• Low noise generation• Low part count
Usually integrates synchronous rectifierTwo resistors to set output voltageInductor and two storage capacitors
►Cons:• Expensive
Step-up controller was the most expensive device in the BOM• Require special capacitors and inductors
ESR in function of extreme high operating frequencies
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Proposal #2: Using a Discrete Step-up ConverterAssisted by the MCU
►Desired features• Extreme low cost• Just a few components outside• Able to operate from V_bat >1.0V• 60% minimum efficiency
►Solution proposed: Fly back converter with bipolar transistor initiated by the user and then assisted by the MCU in the continuity of the operation
• Manual start, then MCU takes control of the conversion• Output voltage up to 3x input voltage• Average efficiency from 60% to 88%
• Even with less efficiency than integrated controllers, the overall cost makes the discrete solution suitable for low-end/low-cost requirements
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Discrete Step-up Converter Assisted by MCU
►Pros:• Extremely low cost• Lowest part count
Just a few resistors, capacitors, one diode, one bipolar transistor and inductorPower_on button used to start conversion
• Smaller board area
►Cons:• Less efficient, reducing battery autonomy
White LED works almost as shunt regulator• Higher noise than obtained with the IC controller
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Discrete Step-up Converter Assisted by MCU
Voltage mode regulation► Step-up conversion starts with “ON” button pressed a few times► Then the MCU takes control of the step-up process
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Discrete Step-up Converter Assisted by MCU
Prototype►Effective low-cost►Adjustable brightness
• Fixed resistors at ACMP►Operates from 1.5V to 1.0V
with standard alkaline batteries
►Over 12 hour continuous operation
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Performance Analysis and Results
► Full operation from 1.5V to 1.1V with both IC and discrete solutions
• 65% min efficiency with discrete circuitry• 80% min efficiency with controller IC
► IC controllers• Better dynamic regulation• Higher efficiency• Low noise• Higher cost
► Discrete converters• Poor dynamic regulation
Good for stable loads• Average efficiency
Better with assisted control• Noisier• Low cost
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What makes Freescale 8-bit MCUs suitable for single cell operation?
►S08 and RS08 cores operating from voltages as low as 1.8V • Easy start-up• Predictable power consumption in function of supply voltage and clock speed
► Internal 32 KHz clock oscillator with integrated FLL • Fast speed to change clock frequency in function of battery state
►RUN, WAIT and several STOP modes with fast wake-up►Flash memory read/write/erase in the full supply range
• No need for additional boosting►20 μS byte write time on Flash
• Short bursts of additional power consumption when storing contents• Some devices with dual bank Flash
► Internal pull-ups and controlled rise and fall times on GPIO• Fewer external devices leaking energy
►Efficient 10- and 12-bit ADC• Simple and continuous mode with programmable conversion and sample time • Internal and external clock sourcing (selectable)• Digital magnitude comparator integrated• Operates in WAIT and STOP3 modes in most of the low power devices
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Freescale Battery Life Calculator
►www.freescale.com/lowpower►Determines the average current
the MCU is consuming and estimate the resulting battery life
►Based on application system variables: V, Hz, °C, % of time in in MCU modes (run, wait, stop3, stop2 and stop1), periodic wakeup interval
►User can select from a variety of standard battery sizes and types or enter battery characteristics directly
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Conclusion
►1.5V batteries are readily available at low cost in many standard footprints and offer high power density, making them ideal in space constrained applications demanding low power consumption and easy replacement
►Freescale supplies a large 8-bit MCU portfolio containing a wide variety of peripherals, sizes of memory, numbers of GPIO, and exclusive low power features allowing the execution of simpler 1.5V systems
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Q&A
►Thank you for attending this presentation.
►In you have any questions, please contact me at: [email protected]
THANK YOU!
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TM
AZ143 – Running Freescale 8-bit MCUs from Single Cell 1.5V BatteriesObjective and AgendaWhy 1.5V? Single Cell Operation RequirementsFirst, Assume We Have a Step-up Boost ConverterWireless Humidity SensorIF Remote ControlMotion/Presence DetectorMC9S08QA4/2Pocket MP3 Player with USB Interface and SD CardMC9S08JM32Blood pressure meterMC9S08LL16�Extending Battery Life with MC9S08LL16 �Clock ManagementHome Care ThermometerMC9RS08LE4Isolated Current Meter MC9S08LL64 Step-up Converter RequirementsDisposable BatteriesCircuit DesignConverter RequirementsProposal #1: Using an Integrated Step-up ConverterIntegrated Step-up Circuit DiagramIntegrated Step-up CircuitIntegrated Step-up FactsProposal #2: Using a Discrete Step-up Converter�Assisted by the MCUDiscrete Step-up Converter Assisted by MCU Discrete Step-up Converter Assisted by MCUDiscrete Step-up Converter Assisted by MCUPerformance Analysis and ResultsWhat makes Freescale 8-bit MCUs suitable for �single cell operation?Freescale Battery Life CalculatorConclusionQ&A