HAPPY LUNAR NEW YEAR 1 IEEE SSCS-2007 Portable Power Management - - PowerPoint PPT Presentation

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IEEE SSCS-2007

HAPPY LUNAR NEW YEAR ☺

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Portable Power Management Challenges and Solutions Jinrong Qian Portable Power Management Applications Feb 16, 2007 IEEE SSCS-2007

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IEEE SSCS-2007

Portable Device Market

100 200 300 400 500 600 700 800 900

2 C Y 3 C Y 4 C Y 5 C Y 6 C Y

Others LGE S Ericsson Siemens Samsung Motorola Nokia

10 20 30 40 50 60 70

2 C Y 3 C Y 4 C Y 5 C Y 6 C Y

Others Lenovo Acer Toshiba HP Dell

10 20 30 40 50 60 70 80 90

2 C Y 3 C Y 4 C Y 5 C Y 6 C Y

Others Fujifilm Nikon Olympus Kodak Sony Canon

5 10 15 20

2 C Y 3 C Y 4 C Y 5 C Y 6 C Y

Others Hitachi Samsung Canon JVC Pana Sony

Cellular Phone Unit (Million) Notebook PC Unit (Million) DSC Unit (Million)

2002 2003 2004 2005 2006 2002 2003 2004 2005 2006 2002 2003 2004 2005 2006 2002 2003 2004 2005 2006

Digital Camcorder Unit (Million)

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IEEE SSCS-2007

Long Battery Run-time and Cycle Life

• High capacity battery chemistry
• Battery Charging
• Accurate gas gauge
• System power management

Safety

• Li-Ion cell battery
• Battery pack electronics
• Authentication

Small Size

• High component integration
• High switching frequency

Portable Power Design Challenges

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IEEE SSCS-2007

Total Portable Power Management for Battery-Driven Electronics...

Longer Battery Life Smaller Size & Weight

Portfolio strength in...

Battery management Low-dropout regulators Low-power DC/DC White-light and RGB, LED drivers Power supervisors LCD bias power

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IEEE SSCS-2007

Battery Chemical Capacity

EDV=3.0V/cell Qmax

Load current: 0.2C

• Battery capacity (Qmax) is defined as amount of charge which can

be extracted from the fully charged cell until its voltage drops below end of discharge voltage (EDV).

• EDV is minimal voltage acceptable for the application or for battery

chemistry, whichever is higher.

CBAT RBAT

Battery Capacity: 1C Discharge rate 1C: Current to completely discharge a battery in one hour Example: 2200mAh battery, 1C discharge rate: 2200mA, 1 hr 0.5C rate: 1100mA, 2hrs 3.6V (Battery rated voltage)

1 2 3 4 5 6 3.0 3.5 4.0 4.5 Capacity, Ah Voltage, V

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IEEE SSCS-2007

Volumetric Energy Density (wh/liter) Gravimetric Energy Density (wh/kg)

18650-2,6Ah (2005)

250 500 450 600

100 150 200

350 400

4 2 3 0 4 8 -L1 8 6 3 4 4 8 -M1 8 6 3 4 4 8 -M3 6 3 3 0 4 8 -L1 6 3 3 0 4 8 -L2

18650-2.2Ah

6 3 3 4 5 0 -L1 5 2 3 4 5 0 -L1 6 3 3 0 4 8 -L3 6 3 3 0 4 8 -L4 6 3 3 4 5 0 -L2 6 3 3 4 5 0 -L3 4 2 3 0 4 8 -L2 5 2 3 4 5 0 -L2

18650-2.4Ah

4 2 3 4 5 0 -L1 3 8 3 5 6 2 -8 0 0 m Ah 3 2 3 4 5 6 -5 4 0 m Ah 4 2 3 4 5 6 -7 8 0 m Ah

Cylindrical Prismatic

Polymer

Li ion battery 18650-1.3Ah (1997) 18650-1.8Ah

Battery Chemistry Development

NiCd, NiMH, Li-Ion Rechargeable Battery

• Battery Capacity Increase by 7% per year

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IEEE SSCS-2007

Long Battery Run-time and Cycle Life Battery Charging

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IEEE SSCS-2007

Li-Ion Charge CC-CV Profile

IPRECHARGE 3.0V/Cell Pre-charge ICHARGE

4.2V/Cell

Fast-charge ITERMINATION Taper Current Battery Voltage Constant Current: 20-30% charging time, 70-80% capacity Constant Voltage: 70-80% charging time, 20-30% capacity Constant Voltage

Pre-charge Timer Safety Timer

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IEEE SSCS-2007

• The higher the cell voltage, the higher the capacity
• Over charging shortens battery cycle life
• Requirements: High accuracy battery charge voltage <1%

Charge Voltage Affects Battery Cycle Life

4.35V 4.3V 4.25V 4.2V

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IEEE SSCS-2007

• Charging Current ≤ 1C rate to prevent overheating, degradation.
• The higher charge current will not short the charge time too much!

“Factors that affect cycle-life and possible degradation mechanisms of a Li-ion cell based on LiCoO2”, Journal of Power Sources 111 (2002) 130-136

Charge Current vs Battery Cycle Life

1.0C 1.1C 1.3C 1.5C 2.0C

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IEEE SSCS-2007

Charger output current is shared: ICHG = IBAT + ISYS Design Challenges: Charger and System Interaction Safety Timer Charge Termination Detection

Charging with an Active System Load

System ISYS + Adapter

• r USB

ICHG IBAT Charger

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IEEE SSCS-2007

Challenge: Pre-charge and Safety Timer Fault

Pre-Charge Mode: Battery voltage may NOT reach the fast charge voltage threshold

• Pre-charge Timer False Warning

Battery may NOT fully charged when the safety time expires

• Safety Timer False Warning

Solution: Keep system off or in low-power mode in pre-charge mode Drawback: Can not operate the system while charging a deeply discharged battery simultaneously

100mA 80mA

+

Adapter

• r USB

System

ICHG ISYS IBAT

Charger

20mA

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IEEE SSCS-2007

Power Path Management Battery Charge Architecture

• Decoupling charge current path from system current path
• Charge current controlled by Q2
• Powering System from adapter through Q1
• Simultaneously powering system and charging battery
• No interaction between charge current and system current

C1

+

• Adapter

System Q1 Q2

Powering System

Charging Battery Controller

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IEEE SSCS-2007

Challenge for Power Path Management Charger

Time

ICHG VOUT IADP Adapter current limit ISYS

System Current System Crash

IADP= ISYS + ICHG

• High AC adapter Current
• May crash the system for high pulse current
• Designing the AC adapter with peak power
• Higher cost
• Larger size

Power Regulation: Dynamic Power Path Management Avoid System Crash IADP

C1

+

• Adapter

System

Q1 Q2

System Current

Charging Battery

Controller

ICHG

ISYS

VOUT

VOUT-MIN

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IEEE SSCS-2007

Dynamic Power Path Management (DPPM)

C1

+

• Adapter
• r USB

System

Q2

Current Control Output Control

ICHG

IADP ISYS

Time

ICHG

System Voltage VDPPM

IADP

AC adapter current limit

ISYS

DPPM Mode

System voltage drops if (ISYS + ICHG) > IAC_LIMIT

• DPPM function :

Reduces the charge current when the system voltage is below VDPPM “Finds” maximum adapter power !!! Battery Supplement Mode

VBAT Charging Current

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IEEE SSCS-2007

Functional Block Diagram

Protection

Regulation Loop

• Battery Voltage
• Charge Current
• USB Current
• System Bus Voltage (DPPM)
• Junction Temperature

Protection

• Battery Temp Detection
• System Short Circuit
• Battery Short Circuit
• Safety Timer

USB Control Charge Control AC USB TMR DPPM TS OUT BAT ISET1 LDO Or Mini USB

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IEEE SSCS-2007

• AC adapter or USB can power the system and charge the battery simultaneously
• Dynamically reduces charge rate to supply sufficient system current
• Selectable USB charge current limits of 100/500mA and up to 1.5A from AC adapter
• Thermal regulation and Battery temperature monitoring

System Solution Example: DPPM Battery Charger

C 10uF

AC USB STAT1 STAT2 USBPG ACPG ISET2 ISET1 TMR VSS OUT OUT OUT CE BAT BAT TS LDO PSEL DPPM

103AT RT2

bq2403x

D1 D2 D4 D3 D6 D5 High: 500mA Low: 100mA R1 R2 High: AC Low: USB 3.3V/20mA High Enable

System Load AC Adapter USB

RT1

R3

Q1 Q2 Q3

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IEEE SSCS-2007

High Accurate Battery Gas Gauging Long Battery Run-time

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IEEE SSCS-2007

Full Use of Available Battery Capacity

+

0% 20% 40% 60% 80% 100%

Capacity Charging Voltage Tolerance Actual Useful Capacity Shutdown Uncertainty due to inaccurate gauging

• Only 80-90% of Available Capacity may actually be used!
• High Accuracy Gas Gauge Increase the Battery Run-time

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IEEE SSCS-2007

Voltage Based Gas Gauge

• External battery voltage can be roughly modeled as V=V0CV-I*RBAT
• Higher Voltage with light load, Lower voltage under heavy load Issue
• Display Remaining Capacity Error: 50-100%
• Unexpected Shutdown

Qmax

1 2 3 4 6 3.0 3.5 4.0 4.5 Capacity, Ah Voltage, V

CBAT RBAT VOCV +

• I

+

• V=V0CV - I*RBAT

5

3.6V Light Load + I*RBAT Heavy load

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IEEE SSCS-2007

Voltage Based Gauging with Aging

Cycle 1 Cycle 100 Cycle 200 Cycle 300 Cycle 400 Cycle 500 Cell Voltage (V)

4.2 4.0 3.8 3.6 3.4 3.2 3.0

0.4 0.8 1.2 1.6 2.0

• Same Voltage, Different State of Charge

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IEEE SSCS-2007

Battery is fully charged During discharge

capacity is integrated

Qmax is updated every

time full discharge

• ccurs

∫ = dt i Q

Coulomb Counting Based Gauging

Q 1 2 3 4 5 6

3.0 3.5 4.0 4.5

Capacity, Ah Li-Ion Battery Cell Voltage EDV (end of discharge voltage) Qmax Disadvantages

Learning cycle needed to update Qmax

Battery capacity degradation with aging (Qmax: 3-5% with 100-cycles) Gauging error increase 1% for every 10-cycle with learning

Self-discharge has to be modeled: Not accurate

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IEEE SSCS-2007

Combine advantages of voltage and current based methods Use voltage based method where no load is applied to battery, to

determine starting SOC and no-load capacity degradation

Use current integration based method when under load Update impedance at every cycle using voltage and current

information

BAT OCV

R I V V × =

• Impedance TrackTM : Handling of Battery Aging

0.06 0.1 0.14 0.18 0.22 0.26 0.30 R(Z) - Ω 0.12 0.08 0.04 Im (Z) - Ω Cycle 1 Cycle 100

Battery Impedance with Aging

Battery DC impedance Fully charged Deeply discharged

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IEEE SSCS-2007

How to Measure and Update Impedance

BAT OCV

R I V V × =

• Data flash contains a fixed table for open circuit voltage as a function
• f remaining capacity OCV = f (SOC)

This is true for all standard Li-ion cells, regardless of manufacturer

• The IT algorithm performs real-time measurements and calculations

during charge and discharge cycles. Impedance RBAT = OCV – VBAT I

100 75 50 25 0 SOC % 4.2 3.93 3.67 3.4

Open Circuit Voltage Profile

OCV VBAT

2 SOC 1 SOC Q Δ Qmax

• =

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IEEE SSCS-2007

System Test Results

20 40 60 80 100 3000 3200 3400 3600 3800 4000 4200 Voltage 1.5 1 0.5 0.5 1 RSOC error

True vs Reported RSOC RSOC Accuracy (%) 0 20 40 60 80 100 RSOC(%)

True SOC (%) SMbus Reported SOC (%)

0 20 40 60 80 100 RSOC (%) 4.2 3.8 3.4 3.0 1.0 0.5

• 0.5
• 1.0
• 1.5

Test conditions: bq27350 gas gauge with Impedance Track technology

• Single Li-Ion battery
• DSC-like load discharge profile
• 1% accuracy

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IEEE SSCS-2007

System Power Management

• Challenge: Higher power demand vs Battery Run-time
• Solution: Dynamic Power Management

Long Battery Run-time

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IEEE SSCS-2007

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 200 300 400 500 600 700 20 40 60 80 100 120

CPU Frequency (MHz) Core Voltage (V) Power Consumption (%) Core Voltage Power Consumption

Voltage Scaling or Positioning Reduces Power Dissipation

VIN EN_1 EN_2 MODE GND

TPS62401

10μF VOUT1 SW1 FB1 DFE_1 SW2 ADJ2 10μF VOUT2

Vcore Vcore_Sel VI/O

μP

• Applications: Laptop CPU, portable device CPU
• The Lower Core voltage, the lower CPU speed and Power Dissipation
• Voltage Identification (VID) through communication lines

t: 100μs/div

VOUT1=1.1V IL: 500mA/div DEF_1: 2V/div VOUT1=1.575V

s 2 CPU CPU

f CV 2 1 P =

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IEEE SSCS-2007

• Synchronous Rectification
• Discontinuous Conduction Mode
• Lower conduction loss
• Lower Switching frequency
• Lower switching loss
• Lower gate drive loss
• Lower quiescent current (<20μA)

PWM Mode VI=3.6V Power Save Mode

High Efficiency Power Converters

+

L Co R VO +

• VIN

Q1 Q2 Most circuits: off Lower IQ iL Iavg t

Comp High Comp Low Vo 0.8% 1.6% PWM Mode Power Save Mode

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IEEE SSCS-2007

Battery Powered Device Safety

• Very Active Battery Materials (Lithium=Bomb)
• Battery Management Electronics: Protection
• Battery Pack Authentication

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IEEE SSCS-2007

Battery Safety

Conference on June 21th, 2006 in Japan

Safety!!!

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IEEE SSCS-2007

How many cases are there ?

• More than 43 cases of events on the Notebook PC was reported during 2001~2003

according to the US Consumer Product Safety Commission.

• Nokia announced that 3 –40 cases of battery explosion occurred in 2004.
• Verizon announced that they had more than 24 cases in 2004.

Safety

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IEEE SSCS-2007

Safety and Thermal Stability

• Safety event: Thermal

runaway

• Device malfunctions possibly

leading to safety event:

• short circuits:
• cell internal
• pack internal
• pack external
• vercharge
• verheating
• verdischarge

Thermal Runaway OCV=4.3V

Scan Rate= 3oC/min

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IEEE SSCS-2007

Temp Sensing

Pack+ Pack-

Voltage ADC Over Voltage Under Voltage Gas Gauge IC

I2C

Chemical Fuse

Q2 Q1

Sense Resistor

bq20z90

Second safety Over Voltage Protection IC bq29412

AFE IC RT

Current ADC

Rs SMBus

SMD SMC

Li-Ion Battery Pack

bq29330

Over current Cell balancing LDO

Battery Pack Electronics

• Over Charge (or over-voltage)

1st : Gas gauge IC

firmware

2nd: Protection IC

• Over Current

Gas gauge IC firmware 1st level (chg or dsg) 2nd level, Safety AFE hardware 3rd level, discharge only

• Short Circuit – AFE hardware.
• Over-Discharge
• Over temperature

Chipset: bq20z90-bq29330: Gas gauge accuracy 1% over battery life

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IEEE SSCS-2007

Counterfeit Battery

• Cheap Replacement Battery
• Functionality Removal
• Without Safety Circuit
• No Protection Circuit
• OEM Lose Business and Reputation
• Loss of public confidence as safety compromised

PACK+ PACK-

Battery Pack

TS

RT: 103AT Protector

Gas Gauge HDQ

Battery Authentication/Security Development

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IEEE SSCS-2007

In General:

• A simple and cost effective method to identify and validate identity.

Identification Driver license Passport

• Specific to Peripherals:
• A simple and cost effective method to ensure peripherals come from authorized

vendors.

• Form factors

Strength: Economies of scale Weakness: Easy to duplicate

• Labeling

Strength: Cheap Weakness: Easily copied & moved around

• User Intervention

Strength: Informed consent Weakness: Requires user motivation, difficult to enforce

What is authentication?

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IEEE SSCS-2007

Battery Authentication/Security Development Solutions

• Identification (ID): bq2022

Fixed challenge, fixed response

• Random challenge-response

bq26150 and bq26100

• Bq20z70/z80/z90 include the SHA-1 based authentication

PACK+ PACK- TS

Protector

Gas Gauge

HDQ

Authentication IC

Host

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IEEE SSCS-2007

System dependent

• Battery Packs:

– Allow discharge only

• Chargers:

– Reduced charging current rate, or lower voltage

• Other Peripherals

– Reduced functionality May choose to simply log that an unauthorized peripheral was used for warranty information.

What if not authenticated?

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IEEE SSCS-2007

Small Size

• High Switching Frequency: Small inductor and capacitor

5 -10MHz DC-DC converter development

s IN BAT ripple BAT IN

f 1 V V I Δ V V L

• =
• High Integration: Power Management IC

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IEEE SSCS-2007

Power Management Challenge: Small Size

Innovation:

• Long battery operation
• Small solution size

Battery Management Supervision

Photo Flash LED Backlight TFT/OLED Display Memory Audio Supply Noise-Sensitive RF Circuit

Integration

Power Conversion

Battery Charging USB Li-Ion battery Adapter Gas Gauge

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IEEE SSCS-2007

TPS65820 7x7mm

L1: 3.3μH ADAPTER CSM1 10μF

VIN

CIN 10μF L1 SM1 L2 SM2 PGND2 VIN_SM2 AC 6 24 ANLG2 OUT 23 2 3 19 21 SCLK INT TS 54 SM3 L3 34 VIN_SM1 PGND1 0.6V-1.8V 600mA L2: 3.3μH CSM2 10μF 1.0V -3.4V 600mA OUT CIN1:10μF OUT CIN2:10μF 46 44 45 47 51 49 52 50 D1 OUT L3:4.7μH SM3SW FB3 39 42 40 41 PGND338 D2-D7: White LEDs

D9

RED GREEN BLUE

D11

OUT

D10

LDO0 LDO1 3.3V/150mA 1.25-3.3V/150mA LDO2 LDO3 LDO4 LDO5 VIN_LDO02 VIN_LDO35 C0 2.2μF C1 2.2μF C2 2.2μF C3 2.2μF C4 2.2μF C5 2.2μF C8 1.0μF C6 1.0μF DPPM AGND2 AGND1 LED_PWM AGND0 TMR SIM ADC_REF LDO35_REF C7 10nF RTC_OUT C9 100mF LDO_PM ISET 18 C10 1.0μF 11 10 4 22 30 5 26 27 28 33 37 32 HOT_RST TRSTPWON BA T OUT COUT 10μF USB CUSB 10μF USB 9 12 BAT 17 RT 103AT RT2 442k 1% PACK + PACK- RT1: Li-Ion Battery SYS_IN OUT 31 35 29 GPIO1 GPIO2 GPIOs (ADC_TRG) 43 53 RESPWRON SDAT ANLG1 PWM OUT R7-R10: 100k

HOST INTERFACE

R1:10Ω R5 39k R6 49.9k R16: 220k R15 100k R4 1k C11:1μF C12 1μF C13 0.1uF OUT Battery ID R3 200k R2 200k OUT D8 55 56 1 R11-R13: 100k R14:33Ω Motor (Buzz) 8 7 RGB LEDs 14 25 48 16 36 13 15 20 CSM3 1μF CIN3 1μF

μP I/O LEDS ANALOG/DIGITAL RTC BATTERY CHARGER RGB BUZZ I2C USB ADAPTER Keyboard Backlight SIM Complete Power Solution: Power Management IC

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IEEE SSCS-2007

Smart Phone

Power Management

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IEEE SSCS-2007

• Longer battery run-time and cycle life
• High capacity battery chemistry development
• High efficiency DC-DC converter
• High accurate gas gauge
• Accurate battery charging
• Device miniaturization
• High Integration
• High frequency
• Safety
• Multi-level Protection
• Authentication

Summary

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IEEE SSCS-2007

Thank you and Happy New Year ☺